SERVER-29908 Move OpObserver callbacks out of CollectionShardingState

25 files changed, 938 insertions, 774 deletions

diff --git a/src/mongo/db/SConscript b/src/mongo/db/SConscript
index 540b4ac0a0d..e3bbf70a02f 100644
--- a/src/mongo/db/SConscript
+++ b/src/mongo/db/SConscript
@@ -1519,8 +1519,6 @@ env.CppUnitTest(
     ],
     LIBDEPS=[
         'keys_collection_document',
-        '$BUILD_DIR/mongo/s/coreshard',
-        '$BUILD_DIR/mongo/s/client/sharding_client',
     ],
 )
 
@@ -1562,10 +1560,9 @@ env.CppUnitTest(
         'logical_time_validator_test.cpp',
     ],
     LIBDEPS=[
+        '$BUILD_DIR/mongo/s/config_server_test_fixture',
         'keys_collection_manager',
         'logical_time_validator',
-        '$BUILD_DIR/mongo/s/config_server_test_fixture',
-        '$BUILD_DIR/mongo/s/coreshard',
     ],
 )
 
@@ -1605,32 +1602,10 @@ env.CppUnitTest(
 )
 
 env.CppUnitTest(
-    target='keys_collection_cache_test',
-    source=[
-        'keys_collection_cache_test.cpp',
-    ],
-    LIBDEPS=[
-        'keys_collection_manager',
-        '$BUILD_DIR/mongo/s/config_server_test_fixture',
-        '$BUILD_DIR/mongo/s/coreshard',
-    ],
-)
-
-env.CppUnitTest(
-    target='key_generator_update_test',
-    source=[
-        'key_generator_update_test.cpp',
-    ],
-    LIBDEPS=[
-        'keys_collection_manager',
-        '$BUILD_DIR/mongo/s/config_server_test_fixture',
-        '$BUILD_DIR/mongo/s/coreshard',
-    ],
-)
-
-env.CppUnitTest(
     target='keys_collection_manager_sharding_test',
     source=[
+        'key_generator_update_test.cpp',
+        'keys_collection_cache_test.cpp',
         'keys_collection_manager_sharding_test.cpp',
     ],
     LIBDEPS=[
diff --git a/src/mongo/db/db.cpp b/src/mongo/db/db.cpp
index 8e27f6a2c26..683d2f3e347 100644
--- a/src/mongo/db/db.cpp
+++ b/src/mongo/db/db.cpp
@@ -108,6 +108,8 @@
 #include "mongo/db/repl/topology_coordinator.h"
 #include "mongo/db/s/balancer/balancer.h"
 #include "mongo/db/s/config/sharding_catalog_manager.h"
+#include "mongo/db/s/config_server_op_observer.h"
+#include "mongo/db/s/shard_server_op_observer.h"
 #include "mongo/db/s/sharded_connection_info.h"
 #include "mongo/db/s/sharding_initialization_mongod.h"
 #include "mongo/db/s/sharding_state.h"
@@ -271,6 +273,13 @@ ExitCode _initAndListen(int listenPort) {
     auto opObserverRegistry = stdx::make_unique<OpObserverRegistry>();
     opObserverRegistry->addObserver(stdx::make_unique<OpObserverImpl>());
     opObserverRegistry->addObserver(stdx::make_unique<UUIDCatalogObserver>());
+
+    if (serverGlobalParams.clusterRole == ClusterRole::ShardServer) {
+        opObserverRegistry->addObserver(stdx::make_unique<ShardServerOpObserver>());
+    } else if (serverGlobalParams.clusterRole == ClusterRole::ConfigServer) {
+        opObserverRegistry->addObserver(stdx::make_unique<ConfigServerOpObserver>());
+    }
+
     serviceContext->setOpObserver(std::move(opObserverRegistry));
 
     DBDirectClientFactory::get(serviceContext).registerImplementation([](OperationContext* opCtx) {
diff --git a/src/mongo/db/key_generator_update_test.cpp b/src/mongo/db/key_generator_update_test.cpp
index ee33e8204bf..5c30b3214eb 100644
--- a/src/mongo/db/key_generator_update_test.cpp
+++ b/src/mongo/db/key_generator_update_test.cpp
@@ -37,10 +37,7 @@
 #include "mongo/db/keys_collection_document.h"
 #include "mongo/db/logical_clock.h"
 #include "mongo/db/namespace_string.h"
-#include "mongo/db/operation_context.h"
-#include "mongo/s/catalog/dist_lock_manager_mock.h"
 #include "mongo/s/config_server_test_fixture.h"
-#include "mongo/s/grid.h"
 #include "mongo/stdx/memory.h"
 #include "mongo/unittest/unittest.h"
 #include "mongo/util/clock_source_mock.h"
@@ -59,12 +56,6 @@ protected:
             Grid::get(operationContext())->catalogClient());
     }
 
-    std::unique_ptr<DistLockManager> makeDistLockManager(
-        std::unique_ptr<DistLockCatalog> distLockCatalog) override {
-        invariant(distLockCatalog);
-        return stdx::make_unique<DistLockManagerMock>(std::move(distLockCatalog));
-    }
-
     KeysCollectionClient* catalogClient() const {
         return _catalogClient.get();
     }
diff --git a/src/mongo/db/keys_collection_manager_sharding_test.cpp b/src/mongo/db/keys_collection_manager_sharding_test.cpp
index 4653653c836..c97ca659dd6 100644
--- a/src/mongo/db/keys_collection_manager_sharding_test.cpp
+++ b/src/mongo/db/keys_collection_manager_sharding_test.cpp
@@ -37,10 +37,7 @@
 #include "mongo/db/keys_collection_manager.h"
 #include "mongo/db/logical_clock.h"
 #include "mongo/db/namespace_string.h"
-#include "mongo/db/operation_context.h"
-#include "mongo/s/catalog/dist_lock_manager_mock.h"
 #include "mongo/s/config_server_test_fixture.h"
-#include "mongo/s/grid.h"
 #include "mongo/stdx/memory.h"
 #include "mongo/unittest/unittest.h"
 #include "mongo/util/clock_source_mock.h"
@@ -76,12 +73,6 @@ protected:
         ConfigServerTestFixture::tearDown();
     }
 
-    std::unique_ptr<DistLockManager> makeDistLockManager(
-        std::unique_ptr<DistLockCatalog> distLockCatalog) override {
-        invariant(distLockCatalog);
-        return stdx::make_unique<DistLockManagerMock>(std::move(distLockCatalog));
-    }
-
 private:
     std::unique_ptr<KeysCollectionManager> _keyManager;
 };
diff --git a/src/mongo/db/logical_time_validator_test.cpp b/src/mongo/db/logical_time_validator_test.cpp
index 90eddb5ec98..5db41df3d72 100644
--- a/src/mongo/db/logical_time_validator_test.cpp
+++ b/src/mongo/db/logical_time_validator_test.cpp
@@ -34,15 +34,11 @@
 #include "mongo/db/logical_clock.h"
 #include "mongo/db/logical_time.h"
 #include "mongo/db/logical_time_validator.h"
-#include "mongo/db/operation_context.h"
 #include "mongo/db/server_options.h"
-#include "mongo/db/service_context.h"
 #include "mongo/db/signed_logical_time.h"
 #include "mongo/db/time_proof_service.h"
 #include "mongo/platform/basic.h"
-#include "mongo/s/catalog/dist_lock_manager_mock.h"
 #include "mongo/s/config_server_test_fixture.h"
-#include "mongo/s/grid.h"
 #include "mongo/stdx/memory.h"
 #include "mongo/unittest/unittest.h"
 #include "mongo/util/clock_source_mock.h"
@@ -79,12 +75,6 @@ protected:
         ConfigServerTestFixture::tearDown();
     }
 
-    std::unique_ptr<DistLockManager> makeDistLockManager(
-        std::unique_ptr<DistLockCatalog> distLockCatalog) override {
-        invariant(distLockCatalog);
-        return stdx::make_unique<DistLockManagerMock>(std::move(distLockCatalog));
-    }
-
     /**
      * Forces KeyManager to refresh cache and generate new keys.
      */
diff --git a/src/mongo/db/op_observer_impl.cpp b/src/mongo/db/op_observer_impl.cpp
index f5675135aad..c343ff63050 100644
--- a/src/mongo/db/op_observer_impl.cpp
+++ b/src/mongo/db/op_observer_impl.cpp
@@ -47,7 +47,6 @@
 #include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/replication_coordinator.h"
 #include "mongo/db/s/collection_sharding_state.h"
-#include "mongo/db/s/sharding_state.h"
 #include "mongo/db/server_options.h"
 #include "mongo/db/session_catalog.h"
 #include "mongo/db/views/durable_view_catalog.h"
@@ -458,12 +457,7 @@ void OpObserverImpl::onUpdate(OperationContext* opCtx, const OplogUpdateEntryArg
     if (args.nss != NamespaceString::kSessionTransactionsTableNamespace) {
         if (!args.fromMigrate) {
             auto css = CollectionShardingState::get(opCtx, args.nss);
-            css->onUpdateOp(opCtx,
-                            args.criteria,
-                            args.update,
-                            args.updatedDoc,
-                            opTime.writeOpTime,
-                            opTime.prePostImageOpTime);
+            css->onUpdateOp(opCtx, args.updatedDoc, opTime.writeOpTime, opTime.prePostImageOpTime);
         }
     }
 
@@ -728,9 +722,6 @@ repl::OpTime OpObserverImpl::onDropCollection(OperationContext* opCtx,
     AuthorizationManager::get(opCtx->getServiceContext())
         ->logOp(opCtx, "c", cmdNss, cmdObj, nullptr);
 
-    auto css = CollectionShardingState::get(opCtx, collectionName);
-    css->onDropCollection(opCtx, collectionName);
-
     // Evict namespace entry from the namespace/uuid cache if it exists.
     NamespaceUUIDCache::get(opCtx).evictNamespace(collectionName);
 
diff --git a/src/mongo/db/pipeline/SConscript b/src/mongo/db/pipeline/SConscript
index fcbb40e3199..1019ee08d1c 100644
--- a/src/mongo/db/pipeline/SConscript
+++ b/src/mongo/db/pipeline/SConscript
@@ -210,6 +210,7 @@ env.CppUnitTest(
         'document_source_lookup_change_post_image_test.cpp',
         'document_source_lookup_test.cpp',
         'document_source_match_test.cpp',
+        'document_source_merge_cursors_test.cpp',
         'document_source_mock_test.cpp',
         'document_source_project_test.cpp',
         'document_source_redact_test.cpp',
@@ -228,6 +229,7 @@ env.CppUnitTest(
         '$BUILD_DIR/mongo/db/repl/replmocks',
         '$BUILD_DIR/mongo/db/service_context',
         '$BUILD_DIR/mongo/executor/thread_pool_task_executor_test_fixture',
+        '$BUILD_DIR/mongo/s/sharding_router_test_fixture',
         '$BUILD_DIR/mongo/util/clock_source_mock',
         'document_source_mock',
         'document_value_test_util',
@@ -235,24 +237,6 @@ env.CppUnitTest(
     ],
 )
 
-# This test depends on the sharding test fixture, which has global initializers that conflict with
-# the ones set in 'document_source_test', so is split into its own test.
-env.CppUnitTest(
-    target='document_source_merge_cursors_test',
-    source=[
-        'document_source_merge_cursors_test.cpp',
-    ],
-    LIBDEPS=[
-        '$BUILD_DIR/mongo/db/auth/authorization_manager_mock_init',
-        '$BUILD_DIR/mongo/db/query/query_request',
-        '$BUILD_DIR/mongo/db/query/query_test_service_context',
-        '$BUILD_DIR/mongo/executor/thread_pool_task_executor_test_fixture',
-        '$BUILD_DIR/mongo/s/sharding_test_fixture',
-        'pipeline',
-        'document_value_test_util',
-    ],
-)
-
 env.CppUnitTest(
     target='document_source_facet_test',
     source='document_source_facet_test.cpp',
diff --git a/src/mongo/db/pipeline/document_source_merge_cursors_test.cpp b/src/mongo/db/pipeline/document_source_merge_cursors_test.cpp
index cdaf6b40bc4..4809ac54b50 100644
--- a/src/mongo/db/pipeline/document_source_merge_cursors_test.cpp
+++ b/src/mongo/db/pipeline/document_source_merge_cursors_test.cpp
@@ -46,7 +46,7 @@
 #include "mongo/executor/thread_pool_task_executor_test_fixture.h"
 #include "mongo/s/catalog/type_shard.h"
 #include "mongo/s/client/shard_registry.h"
-#include "mongo/s/sharding_test_fixture.h"
+#include "mongo/s/sharding_router_test_fixture.h"
 #include "mongo/stdx/memory.h"
 #include "mongo/stdx/thread.h"
 #include "mongo/unittest/unittest.h"
diff --git a/src/mongo/db/pipeline/document_source_sample_test.cpp b/src/mongo/db/pipeline/document_source_sample_test.cpp
index 417a2ff5a34..c1c85924c50 100644
--- a/src/mongo/db/pipeline/document_source_sample_test.cpp
+++ b/src/mongo/db/pipeline/document_source_sample_test.cpp
@@ -48,24 +48,9 @@
 #include "mongo/util/tick_source_mock.h"
 
 namespace mongo {
-
-std::unique_ptr<ServiceContextNoop> makeTestServiceContext() {
-    auto service = stdx::make_unique<ServiceContextNoop>();
-    service->setFastClockSource(stdx::make_unique<ClockSourceMock>());
-    service->setTickSource(stdx::make_unique<TickSourceMock>());
-    return service;
-}
-
 namespace {
-using boost::intrusive_ptr;
 
-static const char* const ns = "unittests.document_source_sample_tests";
-
-// Stub to avoid including the server environment library.
-MONGO_INITIALIZER(SetGlobalEnvironment)(InitializerContext* context) {
-    setGlobalServiceContext(makeTestServiceContext());
-    return Status::OK();
-}
+using boost::intrusive_ptr;
 
 class SampleBasics : public AggregationContextFixture {
 public:
diff --git a/src/mongo/db/s/SConscript b/src/mongo/db/s/SConscript
index 5206a25bfca..0c03223c985 100644
--- a/src/mongo/db/s/SConscript
+++ b/src/mongo/db/s/SConscript
@@ -25,10 +25,12 @@ env.Library(
     target='sharding_runtime_d',
     source=[
         'chunk_splitter.cpp',
+        'config_server_op_observer.cpp',
         'implicit_create_collection.cpp',
         'migration_destination_manager.cpp',
         'session_catalog_migration_destination.cpp',
         'shard_filtering_metadata_refresh.cpp',
+        'shard_server_op_observer.cpp',
     ],
     LIBDEPS=[
         '$BUILD_DIR/mongo/db/db_raii',
@@ -158,7 +160,6 @@ env.CppUnitTest(
     ],
     LIBDEPS=[
         '$BUILD_DIR/mongo/s/config_server_test_fixture',
-        '$BUILD_DIR/mongo/s/coreshard',
         '$BUILD_DIR/mongo/util/version_impl',
         'balancer',
     ]
diff --git a/src/mongo/db/s/balancer/balancer.cpp b/src/mongo/db/s/balancer/balancer.cpp
index 4b6c79c343c..fcabe61f658 100644
--- a/src/mongo/db/s/balancer/balancer.cpp
+++ b/src/mongo/db/s/balancer/balancer.cpp
@@ -47,7 +47,6 @@
 #include "mongo/s/catalog/type_chunk.h"
 #include "mongo/s/catalog_cache.h"
 #include "mongo/s/client/shard_registry.h"
-#include "mongo/s/cluster_identity_loader.h"
 #include "mongo/s/grid.h"
 #include "mongo/s/shard_util.h"
 #include "mongo/stdx/memory.h"
diff --git a/src/mongo/db/s/collection_range_deleter_test.cpp b/src/mongo/db/s/collection_range_deleter_test.cpp
index df1f28be264..beddabc66de 100644
--- a/src/mongo/db/s/collection_range_deleter_test.cpp
+++ b/src/mongo/db/s/collection_range_deleter_test.cpp
@@ -43,7 +43,7 @@
 #include "mongo/s/balancer_configuration.h"
 #include "mongo/s/chunk_version.h"
 #include "mongo/s/client/shard_registry.h"
-#include "mongo/s/sharding_mongod_test_fixture.h"
+#include "mongo/s/shard_server_test_fixture.h"
 #include "mongo/unittest/unittest.h"
 
 namespace mongo {
@@ -54,46 +54,38 @@ using unittest::assertGet;
 using Deletion = CollectionRangeDeleter::Deletion;
 
 const NamespaceString kNss = NamespaceString("foo", "bar");
-const std::string kPattern = "_id";
-const BSONObj kKeyPattern = BSON(kPattern << 1);
-const std::string kShardName{"a"};
-const HostAndPort dummyHost("dummy", 123);
+const std::string kShardKey = "_id";
+const BSONObj kShardKeyPattern = BSON(kShardKey << 1);
 const NamespaceString kAdminSysVer = NamespaceString("admin", "system.version");
 
-class CollectionRangeDeleterTest : public ShardingMongodTestFixture {
+class CollectionRangeDeleterTest : public ShardServerTestFixture {
 protected:
     void setUp() override {
-        _epoch = OID::gen();
-        serverGlobalParams.clusterRole = ClusterRole::ShardServer;
-        ShardingMongodTestFixture::setUp();
-        replicationCoordinator()->alwaysAllowWrites(true);
-        ASSERT_OK(initializeGlobalShardingStateForMongodForTest(ConnectionString(dummyHost)));
-
-        // RemoteCommandTargeterMock::get(shardRegistry()->getConfigShard()->getTargeter())
-        //     ->setConnectionStringReturnValue(kConfigConnStr);
+        ShardServerTestFixture::setUp();
 
-        configTargeter()->setFindHostReturnValue(dummyHost);
+        // Make every test run with a separate epoch
+        _epoch = OID::gen();
 
-        DBDirectClient(operationContext()).createCollection(kNss.ns());
-        {
-            AutoGetCollection autoColl(operationContext(), kNss, MODE_IX);
-            auto collectionShardingState = CollectionShardingState::get(operationContext(), kNss);
-            const KeyPattern skPattern(kKeyPattern);
-            auto cm = ChunkManager::makeNew(
-                kNss,
-                UUID::gen(),
-                kKeyPattern,
-                nullptr,
-                false,
-                epoch(),
-                {ChunkType(kNss,
-                           ChunkRange{skPattern.globalMin(), skPattern.globalMax()},
-                           ChunkVersion(1, 0, epoch()),
-                           ShardId("otherShard"))});
-            collectionShardingState->refreshMetadata(
-                operationContext(),
-                stdx::make_unique<CollectionMetadata>(cm, ShardId("thisShard")));
-        }
+        DBDirectClient client(operationContext());
+        client.createCollection(kNss.ns());
+
+        const KeyPattern keyPattern(kShardKeyPattern);
+        auto cm = ChunkManager::makeNew(
+            kNss,
+            UUID::gen(),
+            keyPattern,
+            nullptr,
+            false,
+            epoch(),
+            {ChunkType(kNss,
+                       ChunkRange{keyPattern.globalMin(), keyPattern.globalMax()},
+                       ChunkVersion(1, 0, epoch()),
+                       ShardId("otherShard"))});
+
+        AutoGetCollection autoColl(operationContext(), kNss, MODE_IX);
+        auto const css = CollectionShardingState::get(operationContext(), kNss);
+        css->refreshMetadata(operationContext(),
+                             stdx::make_unique<CollectionMetadata>(cm, ShardId("thisShard")));
     }
 
     void tearDown() override {
@@ -103,7 +95,7 @@ protected:
             collectionShardingState->refreshMetadata(operationContext(), nullptr);
         }
 
-        ShardingMongodTestFixture::tearDown();
+        ShardServerTestFixture::tearDown();
     }
 
     boost::optional<Date_t> next(CollectionRangeDeleter& rangeDeleter, int maxToDelete) {
@@ -136,19 +128,20 @@ TEST_F(CollectionRangeDeleterTest, EmptyDatabase) {
 // Tests the case that there is data, but it is not in a range to clean.
 TEST_F(CollectionRangeDeleterTest, NoDataInGivenRangeToClean) {
     CollectionRangeDeleter rangeDeleter;
-    const BSONObj insertedDoc = BSON(kPattern << 25);
+    const BSONObj insertedDoc = BSON(kShardKey << 25);
     DBDirectClient dbclient(operationContext());
     dbclient.insert(kNss.toString(), insertedDoc);
-    ASSERT_BSONOBJ_EQ(insertedDoc, dbclient.findOne(kNss.toString(), QUERY(kPattern << 25)));
+    ASSERT_BSONOBJ_EQ(insertedDoc, dbclient.findOne(kNss.toString(), QUERY(kShardKey << 25)));
     std::list<Deletion> ranges;
-    ranges.emplace_back(Deletion{ChunkRange{BSON(kPattern << 0), BSON(kPattern << 10)}, Date_t{}});
+    ranges.emplace_back(
+        Deletion{ChunkRange{BSON(kShardKey << 0), BSON(kShardKey << 10)}, Date_t{}});
     auto when = rangeDeleter.add(std::move(ranges));
     ASSERT(when && *when == Date_t{});
     ASSERT_EQ(1u, rangeDeleter.size());
     ASSERT_TRUE(next(rangeDeleter, 1));
 
     ASSERT_EQ(0u, rangeDeleter.size());
-    ASSERT_BSONOBJ_EQ(insertedDoc, dbclient.findOne(kNss.toString(), QUERY(kPattern << 25)));
+    ASSERT_BSONOBJ_EQ(insertedDoc, dbclient.findOne(kNss.toString(), QUERY(kShardKey << 25)));
 
     ASSERT_FALSE(next(rangeDeleter, 1));
 }
@@ -156,19 +149,19 @@ TEST_F(CollectionRangeDeleterTest, NoDataInGivenRangeToClean) {
 // Tests the case that there is a single document within a range to clean.
 TEST_F(CollectionRangeDeleterTest, OneDocumentInOneRangeToClean) {
     CollectionRangeDeleter rangeDeleter;
-    const BSONObj insertedDoc = BSON(kPattern << 5);
+    const BSONObj insertedDoc = BSON(kShardKey << 5);
     DBDirectClient dbclient(operationContext());
-    dbclient.insert(kNss.toString(), BSON(kPattern << 5));
-    ASSERT_BSONOBJ_EQ(insertedDoc, dbclient.findOne(kNss.toString(), QUERY(kPattern << 5)));
+    dbclient.insert(kNss.toString(), BSON(kShardKey << 5));
+    ASSERT_BSONOBJ_EQ(insertedDoc, dbclient.findOne(kNss.toString(), QUERY(kShardKey << 5)));
 
     std::list<Deletion> ranges;
-    auto deletion = Deletion{ChunkRange(BSON(kPattern << 0), BSON(kPattern << 10)), Date_t{}};
+    auto deletion = Deletion{ChunkRange(BSON(kShardKey << 0), BSON(kShardKey << 10)), Date_t{}};
     ranges.emplace_back(std::move(deletion));
     auto when = rangeDeleter.add(std::move(ranges));
     ASSERT(when && *when == Date_t{});
     ASSERT_TRUE(ranges.empty());  // spliced elements out of it
 
-    auto optNotifn = rangeDeleter.overlaps(ChunkRange(BSON(kPattern << 0), BSON(kPattern << 10)));
+    auto optNotifn = rangeDeleter.overlaps(ChunkRange(BSON(kShardKey << 0), BSON(kShardKey << 10)));
     ASSERT(optNotifn);
     auto notifn = *optNotifn;
     ASSERT(!notifn.ready());
@@ -182,31 +175,31 @@ TEST_F(CollectionRangeDeleterTest, OneDocumentInOneRangeToClean) {
     ASSERT_TRUE(rangeDeleter.isEmpty());
     ASSERT(notifn.ready() && notifn.waitStatus(operationContext()).isOK());
 
-    ASSERT_TRUE(dbclient.findOne(kNss.toString(), QUERY(kPattern << 5)).isEmpty());
+    ASSERT_TRUE(dbclient.findOne(kNss.toString(), QUERY(kShardKey << 5)).isEmpty());
     ASSERT_FALSE(next(rangeDeleter, 1));
-    ASSERT_EQUALS(0ULL, dbclient.count(kAdminSysVer.ns(), BSON(kPattern << "startRangeDeletion")));
+    ASSERT_EQUALS(0ULL, dbclient.count(kAdminSysVer.ns(), BSON(kShardKey << "startRangeDeletion")));
 }
 
 // Tests the case that there are multiple documents within a range to clean.
 TEST_F(CollectionRangeDeleterTest, MultipleDocumentsInOneRangeToClean) {
     CollectionRangeDeleter rangeDeleter;
     DBDirectClient dbclient(operationContext());
-    dbclient.insert(kNss.toString(), BSON(kPattern << 1));
-    dbclient.insert(kNss.toString(), BSON(kPattern << 2));
-    dbclient.insert(kNss.toString(), BSON(kPattern << 3));
-    ASSERT_EQUALS(3ULL, dbclient.count(kNss.toString(), BSON(kPattern << LT << 5)));
+    dbclient.insert(kNss.toString(), BSON(kShardKey << 1));
+    dbclient.insert(kNss.toString(), BSON(kShardKey << 2));
+    dbclient.insert(kNss.toString(), BSON(kShardKey << 3));
+    ASSERT_EQUALS(3ULL, dbclient.count(kNss.toString(), BSON(kShardKey << LT << 5)));
 
     std::list<Deletion> ranges;
-    auto deletion = Deletion{ChunkRange(BSON(kPattern << 0), BSON(kPattern << 10)), Date_t{}};
+    auto deletion = Deletion{ChunkRange(BSON(kShardKey << 0), BSON(kShardKey << 10)), Date_t{}};
     ranges.emplace_back(std::move(deletion));
     auto when = rangeDeleter.add(std::move(ranges));
     ASSERT(when && *when == Date_t{});
 
     ASSERT_TRUE(next(rangeDeleter, 100));
     ASSERT_TRUE(next(rangeDeleter, 100));
-    ASSERT_EQUALS(0ULL, dbclient.count(kNss.toString(), BSON(kPattern << LT << 5)));
+    ASSERT_EQUALS(0ULL, dbclient.count(kNss.toString(), BSON(kShardKey << LT << 5)));
     ASSERT_FALSE(next(rangeDeleter, 100));
-    ASSERT_EQUALS(0ULL, dbclient.count(kAdminSysVer.ns(), BSON(kPattern << "startRangeDeletion")));
+    ASSERT_EQUALS(0ULL, dbclient.count(kAdminSysVer.ns(), BSON(kShardKey << "startRangeDeletion")));
 }
 
 // Tests the case that there are multiple documents within a range to clean, and the range deleter
@@ -214,70 +207,71 @@ TEST_F(CollectionRangeDeleterTest, MultipleDocumentsInOneRangeToClean) {
 TEST_F(CollectionRangeDeleterTest, MultipleCleanupNextRangeCalls) {
     CollectionRangeDeleter rangeDeleter;
     DBDirectClient dbclient(operationContext());
-    dbclient.insert(kNss.toString(), BSON(kPattern << 1));
-    dbclient.insert(kNss.toString(), BSON(kPattern << 2));
-    dbclient.insert(kNss.toString(), BSON(kPattern << 3));
-    ASSERT_EQUALS(3ULL, dbclient.count(kNss.toString(), BSON(kPattern << LT << 5)));
+    dbclient.insert(kNss.toString(), BSON(kShardKey << 1));
+    dbclient.insert(kNss.toString(), BSON(kShardKey << 2));
+    dbclient.insert(kNss.toString(), BSON(kShardKey << 3));
+    ASSERT_EQUALS(3ULL, dbclient.count(kNss.toString(), BSON(kShardKey << LT << 5)));
 
     std::list<Deletion> ranges;
-    auto deletion = Deletion{ChunkRange(BSON(kPattern << 0), BSON(kPattern << 10)), Date_t{}};
+    auto deletion = Deletion{ChunkRange(BSON(kShardKey << 0), BSON(kShardKey << 10)), Date_t{}};
     ranges.emplace_back(std::move(deletion));
     auto when = rangeDeleter.add(std::move(ranges));
     ASSERT(when && *when == Date_t{});
 
     ASSERT_TRUE(next(rangeDeleter, 1));
-    ASSERT_EQUALS(2ULL, dbclient.count(kNss.toString(), BSON(kPattern << LT << 5)));
+    ASSERT_EQUALS(2ULL, dbclient.count(kNss.toString(), BSON(kShardKey << LT << 5)));
 
     ASSERT_TRUE(next(rangeDeleter, 1));
-    ASSERT_EQUALS(1ULL, dbclient.count(kNss.toString(), BSON(kPattern << LT << 5)));
+    ASSERT_EQUALS(1ULL, dbclient.count(kNss.toString(), BSON(kShardKey << LT << 5)));
 
     ASSERT_TRUE(next(rangeDeleter, 1));
     ASSERT_TRUE(next(rangeDeleter, 1));
-    ASSERT_EQUALS(0ULL, dbclient.count(kNss.toString(), BSON(kPattern << LT << 5)));
+    ASSERT_EQUALS(0ULL, dbclient.count(kNss.toString(), BSON(kShardKey << LT << 5)));
     ASSERT_FALSE(next(rangeDeleter, 1));
-    ASSERT_EQUALS(0ULL, dbclient.count(kAdminSysVer.ns(), BSON(kPattern << "startRangeDeletion")));
+    ASSERT_EQUALS(0ULL, dbclient.count(kAdminSysVer.ns(), BSON(kShardKey << "startRangeDeletion")));
 }
 
 // Tests the case that there are two ranges to clean, each containing multiple documents.
 TEST_F(CollectionRangeDeleterTest, MultipleDocumentsInMultipleRangesToClean) {
     CollectionRangeDeleter rangeDeleter;
     DBDirectClient dbclient(operationContext());
-    dbclient.insert(kNss.toString(), BSON(kPattern << 1));
-    dbclient.insert(kNss.toString(), BSON(kPattern << 2));
-    dbclient.insert(kNss.toString(), BSON(kPattern << 3));
-    dbclient.insert(kNss.toString(), BSON(kPattern << 4));
-    dbclient.insert(kNss.toString(), BSON(kPattern << 5));
-    dbclient.insert(kNss.toString(), BSON(kPattern << 6));
-    ASSERT_EQUALS(6ULL, dbclient.count(kNss.toString(), BSON(kPattern << LT << 10)));
+    dbclient.insert(kNss.toString(), BSON(kShardKey << 1));
+    dbclient.insert(kNss.toString(), BSON(kShardKey << 2));
+    dbclient.insert(kNss.toString(), BSON(kShardKey << 3));
+    dbclient.insert(kNss.toString(), BSON(kShardKey << 4));
+    dbclient.insert(kNss.toString(), BSON(kShardKey << 5));
+    dbclient.insert(kNss.toString(), BSON(kShardKey << 6));
+    ASSERT_EQUALS(6ULL, dbclient.count(kNss.toString(), BSON(kShardKey << LT << 10)));
 
     std::list<Deletion> ranges;
     auto later = Date_t::now();
-    ranges.emplace_back(Deletion{ChunkRange{BSON(kPattern << 0), BSON(kPattern << 3)}, later});
+    ranges.emplace_back(Deletion{ChunkRange{BSON(kShardKey << 0), BSON(kShardKey << 3)}, later});
     auto when = rangeDeleter.add(std::move(ranges));
     ASSERT(when && *when == later);
     ASSERT_TRUE(ranges.empty());  // not guaranteed by std, but failure would indicate a problem.
 
     std::list<Deletion> ranges2;
-    ranges2.emplace_back(Deletion{ChunkRange{BSON(kPattern << 4), BSON(kPattern << 7)}, later});
+    ranges2.emplace_back(Deletion{ChunkRange{BSON(kShardKey << 4), BSON(kShardKey << 7)}, later});
     when = rangeDeleter.add(std::move(ranges2));
     ASSERT(!when);
 
     std::list<Deletion> ranges3;
-    ranges3.emplace_back(Deletion{ChunkRange{BSON(kPattern << 3), BSON(kPattern << 4)}, Date_t{}});
+    ranges3.emplace_back(
+        Deletion{ChunkRange{BSON(kShardKey << 3), BSON(kShardKey << 4)}, Date_t{}});
     when = rangeDeleter.add(std::move(ranges3));
     ASSERT(when);
 
-    auto optNotifn1 = rangeDeleter.overlaps(ChunkRange{BSON(kPattern << 0), BSON(kPattern << 3)});
+    auto optNotifn1 = rangeDeleter.overlaps(ChunkRange{BSON(kShardKey << 0), BSON(kShardKey << 3)});
     ASSERT_TRUE(optNotifn1);
     auto& notifn1 = *optNotifn1;
     ASSERT_FALSE(notifn1.ready());
 
-    auto optNotifn2 = rangeDeleter.overlaps(ChunkRange{BSON(kPattern << 4), BSON(kPattern << 7)});
+    auto optNotifn2 = rangeDeleter.overlaps(ChunkRange{BSON(kShardKey << 4), BSON(kShardKey << 7)});
     ASSERT_TRUE(optNotifn2);
     auto& notifn2 = *optNotifn2;
     ASSERT_FALSE(notifn2.ready());
 
-    auto optNotifn3 = rangeDeleter.overlaps(ChunkRange{BSON(kPattern << 3), BSON(kPattern << 4)});
+    auto optNotifn3 = rangeDeleter.overlaps(ChunkRange{BSON(kShardKey << 3), BSON(kShardKey << 4)});
     ASSERT_TRUE(optNotifn3);
     auto& notifn3 = *optNotifn3;
     ASSERT_FALSE(notifn3.ready());
@@ -289,9 +283,9 @@ TEST_F(CollectionRangeDeleterTest, MultipleDocumentsInMultipleRangesToClean) {
     ASSERT_FALSE(notifn1 != *optNotifn1);
 
     // no op log entry yet
-    ASSERT_EQUALS(0ULL, dbclient.count(kAdminSysVer.ns(), BSON(kPattern << "startRangeDeletion")));
+    ASSERT_EQUALS(0ULL, dbclient.count(kAdminSysVer.ns(), BSON(kShardKey << "startRangeDeletion")));
 
-    ASSERT_EQUALS(6ULL, dbclient.count(kNss.ns(), BSON(kPattern << LT << 7)));
+    ASSERT_EQUALS(6ULL, dbclient.count(kNss.ns(), BSON(kShardKey << LT << 7)));
 
     // catch range3, [3..4) only
     auto next1 = next(rangeDeleter, 100);
@@ -299,11 +293,11 @@ TEST_F(CollectionRangeDeleterTest, MultipleDocumentsInMultipleRangesToClean) {
     ASSERT_EQUALS(*next1, Date_t{});
 
     // no op log entry for immediate deletions
-    ASSERT_EQUALS(0ULL, dbclient.count(kAdminSysVer.ns(), BSON(kPattern << "startRangeDeletion")));
+    ASSERT_EQUALS(0ULL, dbclient.count(kAdminSysVer.ns(), BSON(kShardKey << "startRangeDeletion")));
 
     // 3 gone
-    ASSERT_EQUALS(5ULL, dbclient.count(kNss.ns(), BSON(kPattern << LT << 7)));
-    ASSERT_EQUALS(2ULL, dbclient.count(kNss.ns(), BSON(kPattern << LT << 4)));
+    ASSERT_EQUALS(5ULL, dbclient.count(kNss.ns(), BSON(kShardKey << LT << 7)));
+    ASSERT_EQUALS(2ULL, dbclient.count(kNss.ns(), BSON(kShardKey << LT << 4)));
 
     ASSERT_FALSE(notifn1.ready());  // no trigger yet
     ASSERT_FALSE(notifn2.ready());  // no trigger yet
@@ -315,11 +309,11 @@ TEST_F(CollectionRangeDeleterTest, MultipleDocumentsInMultipleRangesToClean) {
     ASSERT_EQUALS(*next2, Date_t{});
 
     // still no op log entry, because not delayed
-    ASSERT_EQUALS(0ULL, dbclient.count(kAdminSysVer.ns(), BSON(kPattern << "startRangeDeletion")));
+    ASSERT_EQUALS(0ULL, dbclient.count(kAdminSysVer.ns(), BSON(kShardKey << "startRangeDeletion")));
 
     // deleted 1, 5 left
-    ASSERT_EQUALS(2ULL, dbclient.count(kNss.ns(), BSON(kPattern << LT << 4)));
-    ASSERT_EQUALS(5ULL, dbclient.count(kNss.ns(), BSON(kPattern << LT << 10)));
+    ASSERT_EQUALS(2ULL, dbclient.count(kNss.ns(), BSON(kShardKey << LT << 4)));
+    ASSERT_EQUALS(5ULL, dbclient.count(kNss.ns(), BSON(kShardKey << LT << 10)));
 
     ASSERT_FALSE(notifn1.ready());  // no trigger yet
     ASSERT_FALSE(notifn2.ready());  // no trigger yet
@@ -336,9 +330,9 @@ TEST_F(CollectionRangeDeleterTest, MultipleDocumentsInMultipleRangesToClean) {
     ASSERT_FALSE(notifn2.ready());  // no trigger yet
 
     // deleted 3, 3 left
-    ASSERT_EQUALS(3ULL, dbclient.count(kNss.ns(), BSON(kPattern << LT << 10)));
+    ASSERT_EQUALS(3ULL, dbclient.count(kNss.ns(), BSON(kShardKey << LT << 10)));
 
-    ASSERT_EQUALS(1ULL, dbclient.count(kAdminSysVer.ns(), BSON(kPattern << "startRangeDeletion")));
+    ASSERT_EQUALS(1ULL, dbclient.count(kAdminSysVer.ns(), BSON(kShardKey << "startRangeDeletion")));
     // clang-format off
     ASSERT_BSONOBJ_EQ(
         BSON("_id" << "startRangeDeletion" << "ns" << kNss.ns()
@@ -364,7 +358,7 @@ TEST_F(CollectionRangeDeleterTest, MultipleDocumentsInMultipleRangesToClean) {
     // clang-format on
 
     // still 3 left
-    ASSERT_EQUALS(3ULL, dbclient.count(kNss.ns(), BSON(kPattern << LT << 10)));
+    ASSERT_EQUALS(3ULL, dbclient.count(kNss.ns(), BSON(kShardKey << LT << 10)));
 
     // delete the remaining documents
     auto next5 = next(rangeDeleter, 100);
@@ -382,7 +376,7 @@ TEST_F(CollectionRangeDeleterTest, MultipleDocumentsInMultipleRangesToClean) {
     // clang-format on
 
     // all docs gone
-    ASSERT_EQUALS(0ULL, dbclient.count(kNss.ns(), BSON(kPattern << LT << 10)));
+    ASSERT_EQUALS(0ULL, dbclient.count(kNss.ns(), BSON(kShardKey << LT << 10)));
 
     // discover there are no more, pop range 2
     auto next6 = next(rangeDeleter, 100);
diff --git a/src/mongo/db/s/collection_sharding_state.cpp b/src/mongo/db/s/collection_sharding_state.cpp
index 3c8d4d6e8d6..d19955f6a3c 100644
--- a/src/mongo/db/s/collection_sharding_state.cpp
+++ b/src/mongo/db/s/collection_sharding_state.cpp
@@ -37,29 +37,16 @@
 #include "mongo/db/catalog_raii.h"
 #include "mongo/db/client.h"
 #include "mongo/db/operation_context.h"
-#include "mongo/db/repl/replication_coordinator.h"
-#include "mongo/db/s/config/sharding_catalog_manager.h"
 #include "mongo/db/s/migration_chunk_cloner_source.h"
 #include "mongo/db/s/migration_source_manager.h"
 #include "mongo/db/s/operation_sharding_state.h"
-#include "mongo/db/s/shard_identity_rollback_notifier.h"
 #include "mongo/db/s/sharded_connection_info.h"
 #include "mongo/db/s/sharding_state.h"
-#include "mongo/db/s/type_shard_identity.h"
-#include "mongo/db/server_options.h"
 #include "mongo/db/server_parameters.h"
 #include "mongo/db/service_context.h"
 #include "mongo/executor/network_interface_factory.h"
 #include "mongo/executor/network_interface_thread_pool.h"
 #include "mongo/executor/thread_pool_task_executor.h"
-#include "mongo/s/balancer_configuration.h"
-#include "mongo/s/catalog/type_config_version.h"
-#include "mongo/s/catalog/type_shard.h"
-#include "mongo/s/catalog/type_shard_collection.h"
-#include "mongo/s/catalog_cache.h"
-#include "mongo/s/catalog_cache_loader.h"
-#include "mongo/s/cluster_identity_loader.h"
-#include "mongo/s/grid.h"
 #include "mongo/s/stale_exception.h"
 #include "mongo/util/log.h"
 
@@ -169,64 +156,6 @@ private:
 const auto getCollectionShardingStateMap =
     ServiceContext::declareDecoration<CollectionShardingStateMap>();
 
-/**
- * Used to perform shard identity initialization once it is certain that the document is committed.
- */
-class ShardIdentityLogOpHandler final : public RecoveryUnit::Change {
-public:
-    ShardIdentityLogOpHandler(OperationContext* opCtx, ShardIdentityType shardIdentity)
-        : _opCtx(opCtx), _shardIdentity(std::move(shardIdentity)) {}
-
-    void commit() override {
-        fassertNoTrace(
-            40071, ShardingState::get(_opCtx)->initializeFromShardIdentity(_opCtx, _shardIdentity));
-    }
-
-    void rollback() override {}
-
-private:
-    OperationContext* _opCtx;
-    const ShardIdentityType _shardIdentity;
-};
-
-/**
- * Used to notify the catalog cache loader of a new collection version and invalidate the in-memory
- * routing table cache once the oplog updates are committed and become visible.
- */
-class CollectionVersionLogOpHandler final : public RecoveryUnit::Change {
-public:
-    CollectionVersionLogOpHandler(OperationContext* opCtx, const NamespaceString& nss)
-        : _opCtx(opCtx), _nss(nss) {}
-
-    void commit() override {
-        invariant(_opCtx->lockState()->isCollectionLockedForMode(_nss.ns(), MODE_IX));
-
-        CatalogCacheLoader::get(_opCtx).notifyOfCollectionVersionUpdate(_nss);
-
-        // This is a hack to get around CollectionShardingState::refreshMetadata() requiring the X
-        // lock: markNotShardedAtStepdown() doesn't have a lock check. Temporary measure until
-        // SERVER-31595 removes the X lock requirement.
-        CollectionShardingState::get(_opCtx, _nss)->markNotShardedAtStepdown();
-    }
-
-    void rollback() override {}
-
-private:
-    OperationContext* _opCtx;
-    const NamespaceString _nss;
-};
-
-/**
- * Caller must hold the global lock in some mode other than MODE_NONE.
- */
-bool isStandaloneOrPrimary(OperationContext* opCtx) {
-    dassert(opCtx->lockState()->isLocked());
-    auto replCoord = repl::ReplicationCoordinator::get(opCtx);
-    bool isReplSet = replCoord->getReplicationMode() == repl::ReplicationCoordinator::modeReplSet;
-    return !isReplSet || (repl::ReplicationCoordinator::get(opCtx)->getMemberState() ==
-                          repl::MemberState::RS_PRIMARY);
-}
-
 }  // namespace
 
 CollectionShardingState::CollectionShardingState(ServiceContext* sc, NamespaceString nss)
@@ -394,24 +323,6 @@ void CollectionShardingState::onInsertOp(OperationContext* opCtx,
                                          const repl::OpTime& opTime) {
     dassert(opCtx->lockState()->isCollectionLockedForMode(_nss.ns(), MODE_IX));
 
-    if (serverGlobalParams.clusterRole == ClusterRole::ShardServer) {
-        if (_nss == NamespaceString::kServerConfigurationNamespace) {
-            if (auto idElem = insertedDoc["_id"]) {
-                if (idElem.str() == ShardIdentityType::IdName) {
-                    auto shardIdentityDoc =
-                        uassertStatusOK(ShardIdentityType::fromBSON(insertedDoc));
-                    uassertStatusOK(shardIdentityDoc.validate());
-                    opCtx->recoveryUnit()->registerChange(
-                        new ShardIdentityLogOpHandler(opCtx, std::move(shardIdentityDoc)));
-                }
-            }
-        }
-
-        if (ShardingState::get(opCtx)->enabled()) {
-            _incrementChunkOnInsertOrUpdate(opCtx, insertedDoc, insertedDoc.objsize());
-        }
-    }
-
     checkShardVersionOrThrow(opCtx);
 
     if (_sourceMgr) {
@@ -420,23 +331,11 @@ void CollectionShardingState::onInsertOp(OperationContext* opCtx,
 }
 
 void CollectionShardingState::onUpdateOp(OperationContext* opCtx,
-                                         const BSONObj& query,
-                                         const BSONObj& update,
                                          const BSONObj& updatedDoc,
                                          const repl::OpTime& opTime,
                                          const repl::OpTime& prePostImageOpTime) {
     dassert(opCtx->lockState()->isCollectionLockedForMode(_nss.ns(), MODE_IX));
 
-    if (serverGlobalParams.clusterRole == ClusterRole::ShardServer) {
-        if (_nss.ns() == NamespaceString::kShardConfigCollectionsCollectionName) {
-            _onConfigCollectionsUpdateOp(opCtx, query, update, updatedDoc);
-        }
-
-        if (ShardingState::get(opCtx)->enabled()) {
-            _incrementChunkOnInsertOrUpdate(opCtx, updatedDoc, update.objsize());
-        }
-    }
-
     checkShardVersionOrThrow(opCtx);
 
     if (_sourceMgr) {
@@ -455,41 +354,6 @@ void CollectionShardingState::onDeleteOp(OperationContext* opCtx,
                                          const repl::OpTime& preImageOpTime) {
     dassert(opCtx->lockState()->isCollectionLockedForMode(_nss.ns(), MODE_IX));
 
-    if (serverGlobalParams.clusterRole == ClusterRole::ShardServer) {
-        if (_nss.ns() == NamespaceString::kShardConfigCollectionsCollectionName) {
-            _onConfigDeleteInvalidateCachedMetadataAndNotify(opCtx, deleteState.documentKey);
-        }
-
-        if (_nss == NamespaceString::kServerConfigurationNamespace) {
-            if (auto idElem = deleteState.documentKey["_id"]) {
-                auto idStr = idElem.str();
-                if (idStr == ShardIdentityType::IdName) {
-                    if (!repl::ReplicationCoordinator::get(opCtx)->getMemberState().rollback()) {
-                        uasserted(40070,
-                                  "cannot delete shardIdentity document while in --shardsvr mode");
-                    } else {
-                        warning() << "Shard identity document rolled back.  Will shut down after "
-                                     "finishing rollback.";
-                        ShardIdentityRollbackNotifier::get(opCtx)->recordThatRollbackHappened();
-                    }
-                }
-            }
-        }
-    }
-
-    if (serverGlobalParams.clusterRole == ClusterRole::ConfigServer) {
-        if (_nss == VersionType::ConfigNS) {
-            if (!repl::ReplicationCoordinator::get(opCtx)->getMemberState().rollback()) {
-                uasserted(40302, "cannot delete config.version document while in --configsvr mode");
-            } else {
-                // Throw out any cached information related to the cluster ID.
-                ShardingCatalogManager::get(opCtx)
-                    ->discardCachedConfigDatabaseInitializationState();
-                ClusterIdentityLoader::get(opCtx)->discardCachedClusterId();
-            }
-        }
-    }
-
     checkShardVersionOrThrow(opCtx);
 
     if (_sourceMgr && deleteState.isMigrating) {
@@ -497,100 +361,6 @@ void CollectionShardingState::onDeleteOp(OperationContext* opCtx,
     }
 }
 
-void CollectionShardingState::onDropCollection(OperationContext* opCtx,
-                                               const NamespaceString& collectionName) {
-    dassert(opCtx->lockState()->isCollectionLockedForMode(_nss.ns(), MODE_IX));
-
-    if (serverGlobalParams.clusterRole == ClusterRole::ShardServer &&
-        _nss == NamespaceString::kServerConfigurationNamespace) {
-        // Dropping system collections is not allowed for end users.
-        invariant(!opCtx->writesAreReplicated());
-        invariant(repl::ReplicationCoordinator::get(opCtx)->getMemberState().rollback());
-
-        // Can't confirm whether there was a ShardIdentity document or not yet, so assume there was
-        // one and shut down the process to clear the in-memory sharding state.
-        warning() << "admin.system.version collection rolled back.  Will shut down after "
-                     "finishing rollback";
-        ShardIdentityRollbackNotifier::get(opCtx)->recordThatRollbackHappened();
-    }
-
-    if (serverGlobalParams.clusterRole == ClusterRole::ConfigServer) {
-        if (_nss == VersionType::ConfigNS) {
-            if (!repl::ReplicationCoordinator::get(opCtx)->getMemberState().rollback()) {
-                uasserted(40303, "cannot drop config.version document while in --configsvr mode");
-            } else {
-                // Throw out any cached information related to the cluster ID.
-                ShardingCatalogManager::get(opCtx)
-                    ->discardCachedConfigDatabaseInitializationState();
-                ClusterIdentityLoader::get(opCtx)->discardCachedClusterId();
-            }
-        }
-    }
-}
-
-void CollectionShardingState::_onConfigCollectionsUpdateOp(OperationContext* opCtx,
-                                                           const BSONObj& query,
-                                                           const BSONObj& update,
-                                                           const BSONObj& updatedDoc) {
-    dassert(opCtx->lockState()->isCollectionLockedForMode(_nss.ns(), MODE_IX));
-    invariant(serverGlobalParams.clusterRole == ClusterRole::ShardServer);
-
-    // Notification of routing table changes are only needed on secondaries.
-    if (isStandaloneOrPrimary(opCtx)) {
-        return;
-    }
-
-    // Extract which user collection was updated.
-    std::string updatedCollection;
-    fassert(40477,
-            bsonExtractStringField(query, ShardCollectionType::ns.name(), &updatedCollection));
-
-    // Parse the '$set' update.
-    BSONElement setElement;
-    Status setStatus = bsonExtractTypedField(update, StringData("$set"), Object, &setElement);
-    if (setStatus.isOK()) {
-        BSONObj setField = setElement.Obj();
-        const NamespaceString updatedNss(updatedCollection);
-
-        // Need the WUOW to retain the lock for CollectionVersionLogOpHandler::commit().
-        AutoGetCollection autoColl(opCtx, updatedNss, MODE_IX);
-
-        if (setField.hasField(ShardCollectionType::lastRefreshedCollectionVersion.name())) {
-            opCtx->recoveryUnit()->registerChange(
-                new CollectionVersionLogOpHandler(opCtx, updatedNss));
-        }
-
-        if (setField.hasField(ShardCollectionType::enterCriticalSectionCounter.name())) {
-            // This is a hack to get around CollectionShardingState::refreshMetadata() requiring the
-            // X lock: markNotShardedAtStepdown() doesn't have a lock check. Temporary measure until
-            // SERVER-31595 removes the X lock requirement.
-            CollectionShardingState::get(opCtx, updatedNss)->markNotShardedAtStepdown();
-        }
-    }
-}
-
-void CollectionShardingState::_onConfigDeleteInvalidateCachedMetadataAndNotify(
-    OperationContext* opCtx, const BSONObj& query) {
-    dassert(opCtx->lockState()->isCollectionLockedForMode(_nss.ns(), MODE_IX));
-    invariant(serverGlobalParams.clusterRole == ClusterRole::ShardServer);
-
-    // Notification of routing table changes are only needed on secondaries.
-    if (isStandaloneOrPrimary(opCtx)) {
-        return;
-    }
-
-    // Extract which collection entry is being deleted from the _id field.
-    std::string deletedCollection;
-    fassert(40479,
-            bsonExtractStringField(query, ShardCollectionType::ns.name(), &deletedCollection));
-    const NamespaceString deletedNss(deletedCollection);
-
-    // Need the WUOW to retain the lock for CollectionVersionLogOpHandler::commit().
-    AutoGetCollection autoColl(opCtx, deletedNss, MODE_IX);
-
-    opCtx->recoveryUnit()->registerChange(new CollectionVersionLogOpHandler(opCtx, deletedNss));
-}
-
 bool CollectionShardingState::_checkShardVersionOk(OperationContext* opCtx,
                                                    std::string* errmsg,
                                                    ChunkVersion* expectedShardVersion,
@@ -681,58 +451,4 @@ bool CollectionShardingState::_checkShardVersionOk(OperationContext* opCtx,
     MONGO_UNREACHABLE;
 }
 
-uint64_t CollectionShardingState::_incrementChunkOnInsertOrUpdate(OperationContext* opCtx,
-                                                                  const BSONObj& document,
-                                                                  long dataWritten) {
-
-    // Here, get the collection metadata and check if it exists. If it doesn't exist, then the
-    // collection is not sharded, and we can simply return -1.
-    ScopedCollectionMetadata metadata = getMetadata();
-    if (!metadata) {
-        return -1;
-    }
-
-    std::shared_ptr<ChunkManager> cm = metadata->getChunkManager();
-    const ShardKeyPattern& shardKeyPattern = cm->getShardKeyPattern();
-
-    // Each inserted/updated document should contain the shard key. The only instance in which a
-    // document could not contain a shard key is if the insert/update is performed through mongod
-    // explicitly, as opposed to first routed through mongos.
-    BSONObj shardKey = shardKeyPattern.extractShardKeyFromDoc(document);
-    if (shardKey.woCompare(BSONObj()) == 0) {
-        warning() << "inserting document " << document.toString() << " without shard key pattern "
-                  << shardKeyPattern << " into a sharded collection";
-        return -1;
-    }
-
-    // Use the shard key to locate the chunk into which the document was updated, and increment the
-    // number of bytes tracked for the chunk. Note that we can assume the simple collation, because
-    // shard keys do not support non-simple collations.
-    auto chunk = cm->findIntersectingChunkWithSimpleCollation(shardKey);
-    chunk->addBytesWritten(dataWritten);
-
-    // If the chunk becomes too large, then we call the ChunkSplitter to schedule a split. Then, we
-    // reset the tracking for that chunk to 0.
-    if (_shouldSplitChunk(opCtx, shardKeyPattern, *chunk)) {
-        // TODO: call ChunkSplitter here
-        chunk->clearBytesWritten();
-    }
-
-    return chunk->getBytesWritten();
-}
-
-bool CollectionShardingState::_shouldSplitChunk(OperationContext* opCtx,
-                                                const ShardKeyPattern& shardKeyPattern,
-                                                const Chunk& chunk) {
-
-    const auto balancerConfig = Grid::get(opCtx)->getBalancerConfiguration();
-    invariant(balancerConfig);
-
-    const KeyPattern keyPattern = shardKeyPattern.getKeyPattern();
-    const bool minIsInf = (0 == keyPattern.globalMin().woCompare(chunk.getMin()));
-    const bool maxIsInf = (0 == keyPattern.globalMax().woCompare(chunk.getMax()));
-
-    return chunk.shouldSplit(balancerConfig->getMaxChunkSizeBytes(), minIsInf, maxIsInf);
-}
-
 }  // namespace mongo
diff --git a/src/mongo/db/s/collection_sharding_state.h b/src/mongo/db/s/collection_sharding_state.h
index 30ba8a295d0..14b403cd93f 100644
--- a/src/mongo/db/s/collection_sharding_state.h
+++ b/src/mongo/db/s/collection_sharding_state.h
@@ -32,21 +32,14 @@
 #include <string>
 
 #include "mongo/base/disallow_copying.h"
-#include "mongo/base/string_data.h"
+#include "mongo/bson/bsonobj.h"
 #include "mongo/db/namespace_string.h"
 #include "mongo/db/s/metadata_manager.h"
-#include "mongo/util/concurrency/notification.h"
 
 namespace mongo {
 
-class BalancerConfiguration;
-class BSONObj;
-class BSONObjBuilder;
-struct ChunkVersion;
-class CollectionMetadata;
 class MigrationSourceManager;
 class OperationContext;
-class Timestamp;
 
 /**
  * Contains all sharding-related runtime state for a given collection. One such object is assigned
@@ -229,8 +222,6 @@ public:
                     const BSONObj& insertedDoc,
                     const repl::OpTime& opTime);
     void onUpdateOp(OperationContext* opCtx,
-                    const BSONObj& query,
-                    const BSONObj& update,
                     const BSONObj& updatedDoc,
                     const repl::OpTime& opTime,
                     const repl::OpTime& prePostImageOpTime);
@@ -238,52 +229,9 @@ public:
                     const DeleteState& deleteState,
                     const repl::OpTime& opTime,
                     const repl::OpTime& preImageOpTime);
-    void onDropCollection(OperationContext* opCtx, const NamespaceString& collectionName);
 
 private:
     /**
-     * This runs on updates to the shard's persisted cache of the config server's
-     * config.collections collection.
-     *
-     * If an update occurs to the 'lastRefreshedCollectionVersion' field, registers a task on the
-     * opCtx -- to run after writes from the oplog are committed and visible to reads -- to notify
-     * the catalog cache loader of a new collection version and clear the routing table so the next
-     * caller with routing information will provoke a routing table refresh. When
-     * 'lastRefreshedCollectionVersion' is in 'update', it means that a chunk metadata refresh
-     * finished being applied to the collection's locally persisted metadata store.
-     *
-     * If an update occurs to the 'enterCriticalSectionSignal' field, simply clear the routing table
-     * immediately. This will provoke the next secondary caller to refresh through the primary,
-     * blocking behind the critical section.
-     *
-     * query - BSON with an _id that identifies which collections entry is being updated.
-     * update - the update being applied to the collections entry.
-     * updatedDoc - the document identified by 'query' with the 'update' applied.
-     *
-     * This only runs on secondaries.
-     * The global exclusive lock is expected to be held by the caller.
-     */
-    void _onConfigCollectionsUpdateOp(OperationContext* opCtx,
-                                      const BSONObj& query,
-                                      const BSONObj& update,
-                                      const BSONObj& updatedDoc);
-
-    /**
-     * Invalidates the in-memory routing table cache when a collection is dropped, so the next
-     * caller with routing information will provoke a routing table refresh and see the drop.
-     *
-     * Registers a task on the opCtx -- to run after writes from the oplog are committed and visible
-     * to reads.
-     *
-     * query - BSON with an _id field that identifies which collections entry is being updated.
-     *
-     * This only runs on secondaries.
-     * The global exclusive lock is expected to be held by the caller.
-     */
-    void _onConfigDeleteInvalidateCachedMetadataAndNotify(OperationContext* opCtx,
-                                                          const BSONObj& query);
-
-    /**
      * Checks whether the shard version of the operation matches that of the collection.
      *
      * opCtx - Operation context from which to retrieve the operation's expected version.
@@ -301,23 +249,6 @@ private:
                               ChunkVersion* expectedShardVersion,
                               ChunkVersion* actualShardVersion);
 
-    /**
-     * If the collection is sharded, finds the chunk that contains the specified document, and
-     * increments the size tracked for that chunk by the specified amount of data written, in
-     * bytes. Returns the number of total bytes on that chunk, after the data is written.
-     */
-    uint64_t _incrementChunkOnInsertOrUpdate(OperationContext* opCtx,
-                                             const BSONObj& document,
-                                             long dataWritten);
-
-    /**
-     * Returns true if the total number of bytes on the specified chunk nears the max size of
-     * a shard.
-     */
-    bool _shouldSplitChunk(OperationContext* opCtx,
-                           const ShardKeyPattern& shardKeyPattern,
-                           const Chunk& chunk);
-
     // Namespace this state belongs to.
     const NamespaceString _nss;
 
diff --git a/src/mongo/db/s/collection_sharding_state_test.cpp b/src/mongo/db/s/collection_sharding_state_test.cpp
index ee083fec502..d50d0b10d86 100644
--- a/src/mongo/db/s/collection_sharding_state_test.cpp
+++ b/src/mongo/db/s/collection_sharding_state_test.cpp
@@ -28,6 +28,7 @@
 #include "mongo/platform/basic.h"
 
 #include "mongo/db/catalog_raii.h"
+#include "mongo/db/dbdirectclient.h"
 #include "mongo/db/namespace_string.h"
 #include "mongo/db/s/collection_sharding_state.h"
 #include "mongo/db/s/sharding_state.h"
@@ -39,7 +40,7 @@ namespace {
 
 const NamespaceString kTestNss("TestDB", "TestColl");
 
-class CollShardingStateTest : public ShardServerTestFixture {
+class CollectionShardingStateTest : public ShardServerTestFixture {
 public:
     void setUp() override {
         ShardServerTestFixture::setUp();
@@ -62,106 +63,63 @@ private:
     int _initCallCount = 0;
 };
 
-TEST_F(CollShardingStateTest, GlobalInitGetsCalledAfterWriteCommits) {
-    // Must hold a lock to call initializeFromShardIdentity, which is called by the op observer on
-    // the shard identity document.
-    Lock::GlobalWrite lock(operationContext());
-
-    CollectionShardingState collShardingState(getServiceContext(),
-                                              NamespaceString::kServerConfigurationNamespace);
-
+TEST_F(CollectionShardingStateTest, GlobalInitGetsCalledAfterWriteCommits) {
     ShardIdentityType shardIdentity;
     shardIdentity.setConfigsvrConnString(
         ConnectionString(ConnectionString::SET, "a:1,b:2", "config"));
     shardIdentity.setShardName("a");
     shardIdentity.setClusterId(OID::gen());
 
-    WriteUnitOfWork wuow(operationContext());
-    collShardingState.onInsertOp(operationContext(), shardIdentity.toBSON(), {});
-
-    ASSERT_EQ(0, getInitCallCount());
-
-    wuow.commit();
-
+    DBDirectClient client(operationContext());
+    client.insert("admin.system.version", shardIdentity.toBSON());
     ASSERT_EQ(1, getInitCallCount());
 }
 
-TEST_F(CollShardingStateTest, GlobalInitDoesntGetCalledIfWriteAborts) {
-    // Must hold a lock to call initializeFromShardIdentity, which is called by the op observer on
-    // the shard identity document.
-    Lock::GlobalWrite lock(operationContext());
-
-    CollectionShardingState collShardingState(getServiceContext(),
-                                              NamespaceString::kServerConfigurationNamespace);
-
+TEST_F(CollectionShardingStateTest, GlobalInitDoesntGetCalledIfWriteAborts) {
     ShardIdentityType shardIdentity;
     shardIdentity.setConfigsvrConnString(
         ConnectionString(ConnectionString::SET, "a:1,b:2", "config"));
     shardIdentity.setShardName("a");
     shardIdentity.setClusterId(OID::gen());
 
+    // This part of the test ensures that the collection exists for the AutoGetCollection below to
+    // find and also validates that the initializer does not get called for non-sharding documents
+    DBDirectClient client(operationContext());
+    client.insert("admin.system.version", BSON("_id" << 1));
+    ASSERT_EQ(0, getInitCallCount());
+
     {
-        WriteUnitOfWork wuow(operationContext());
-        collShardingState.onInsertOp(operationContext(), shardIdentity.toBSON(), {});
+        AutoGetCollection autoColl(
+            operationContext(), NamespaceString("admin.system.version"), MODE_IX);
 
+        WriteUnitOfWork wuow(operationContext());
+        ASSERT_OK(autoColl.getCollection()->insertDocument(
+            operationContext(), shardIdentity.toBSON(), {}, false));
         ASSERT_EQ(0, getInitCallCount());
     }
 
     ASSERT_EQ(0, getInitCallCount());
 }
 
-TEST_F(CollShardingStateTest, GlobalInitDoesntGetsCalledIfNSIsNotForShardIdentity) {
-    // Must hold a lock to call initializeFromShardIdentity, which is called by the op observer on
-    // the shard identity document.
-    Lock::GlobalWrite lock(operationContext());
-
-    CollectionShardingState collShardingState(getServiceContext(), NamespaceString("admin.user"));
-
+TEST_F(CollectionShardingStateTest, GlobalInitDoesntGetsCalledIfNSIsNotForShardIdentity) {
     ShardIdentityType shardIdentity;
     shardIdentity.setConfigsvrConnString(
         ConnectionString(ConnectionString::SET, "a:1,b:2", "config"));
     shardIdentity.setShardName("a");
     shardIdentity.setClusterId(OID::gen());
 
-    WriteUnitOfWork wuow(operationContext());
-    collShardingState.onInsertOp(operationContext(), shardIdentity.toBSON(), {});
-
-    ASSERT_EQ(0, getInitCallCount());
-
-    wuow.commit();
-
+    DBDirectClient client(operationContext());
+    client.insert("admin.user", shardIdentity.toBSON());
     ASSERT_EQ(0, getInitCallCount());
 }
 
-TEST_F(CollShardingStateTest, OnInsertOpThrowWithIncompleteShardIdentityDocument) {
-    // Must hold a lock to call CollectionShardingState::onInsertOp.
-    Lock::GlobalWrite lock(operationContext());
-
-    CollectionShardingState collShardingState(getServiceContext(),
-                                              NamespaceString::kServerConfigurationNamespace);
-
+TEST_F(CollectionShardingStateTest, OnInsertOpThrowWithIncompleteShardIdentityDocument) {
     ShardIdentityType shardIdentity;
     shardIdentity.setShardName("a");
 
-    ASSERT_THROWS(collShardingState.onInsertOp(operationContext(), shardIdentity.toBSON(), {}),
-                  AssertionException);
-}
-
-TEST_F(CollShardingStateTest, GlobalInitDoesntGetsCalledIfShardIdentityDocWasNotInserted) {
-    // Must hold a lock to call CollectionShardingState::onInsertOp.
-    Lock::GlobalWrite lock(operationContext());
-
-    CollectionShardingState collShardingState(getServiceContext(),
-                                              NamespaceString::kServerConfigurationNamespace);
-
-    WriteUnitOfWork wuow(operationContext());
-    collShardingState.onInsertOp(operationContext(), BSON("_id" << 1), {});
-
-    ASSERT_EQ(0, getInitCallCount());
-
-    wuow.commit();
-
-    ASSERT_EQ(0, getInitCallCount());
+    DBDirectClient client(operationContext());
+    client.insert("admin.system.version", shardIdentity.toBSON());
+    ASSERT(!client.getLastError().empty());
 }
 
 /**
@@ -170,7 +128,7 @@ TEST_F(CollShardingStateTest, GlobalInitDoesntGetsCalledIfShardIdentityDocWasNot
  * that DeleteState's constructor will extract from its `doc` argument into its member
  * DeleteState::documentKey.
  */
-auto makeAMetadata(BSONObj const& keyPattern) -> std::unique_ptr<CollectionMetadata> {
+std::unique_ptr<CollectionMetadata> makeAMetadata(BSONObj const& keyPattern) {
     const OID epoch = OID::gen();
     auto range = ChunkRange(BSON("key" << MINKEY), BSON("key" << MAXKEY));
     auto chunk = ChunkType(kTestNss, std::move(range), ChunkVersion(1, 0, epoch), ShardId("other"));
@@ -179,7 +137,9 @@ auto makeAMetadata(BSONObj const& keyPattern) -> std::unique_ptr<CollectionMetad
     return stdx::make_unique<CollectionMetadata>(std::move(cm), ShardId("this"));
 }
 
-TEST_F(CollShardingStateTest, MakeDeleteStateUnsharded) {
+using DeleteStateTest = ShardServerTestFixture;
+
+TEST_F(DeleteStateTest, MakeDeleteStateUnsharded) {
     AutoGetCollection autoColl(operationContext(), kTestNss, MODE_IX);
     auto* css = CollectionShardingState::get(operationContext(), kTestNss);
 
@@ -201,7 +161,7 @@ TEST_F(CollShardingStateTest, MakeDeleteStateUnsharded) {
     ASSERT_FALSE(deleteState.isMigrating);
 }
 
-TEST_F(CollShardingStateTest, MakeDeleteStateShardedWithoutIdInShardKey) {
+TEST_F(DeleteStateTest, MakeDeleteStateShardedWithoutIdInShardKey) {
     AutoGetCollection autoColl(operationContext(), kTestNss, MODE_IX);
     auto* css = CollectionShardingState::get(operationContext(), kTestNss);
 
@@ -228,7 +188,7 @@ TEST_F(CollShardingStateTest, MakeDeleteStateShardedWithoutIdInShardKey) {
     ASSERT_FALSE(deleteState.isMigrating);
 }
 
-TEST_F(CollShardingStateTest, MakeDeleteStateShardedWithIdInShardKey) {
+TEST_F(DeleteStateTest, MakeDeleteStateShardedWithIdInShardKey) {
     AutoGetCollection autoColl(operationContext(), kTestNss, MODE_IX);
     auto* css = CollectionShardingState::get(operationContext(), kTestNss);
 
@@ -254,7 +214,7 @@ TEST_F(CollShardingStateTest, MakeDeleteStateShardedWithIdInShardKey) {
     ASSERT_FALSE(deleteState.isMigrating);
 }
 
-TEST_F(CollShardingStateTest, MakeDeleteStateShardedWithIdHashInShardKey) {
+TEST_F(DeleteStateTest, MakeDeleteStateShardedWithIdHashInShardKey) {
     AutoGetCollection autoColl(operationContext(), kTestNss, MODE_IX);
     auto* css = CollectionShardingState::get(operationContext(), kTestNss);
 
diff --git a/src/mongo/db/s/config_server_op_observer.cpp b/src/mongo/db/s/config_server_op_observer.cpp
new file mode 100644
index 00000000000..6b52c94ef37
--- /dev/null
+++ b/src/mongo/db/s/config_server_op_observer.cpp
@@ -0,0 +1,78 @@
+/**
+ *    Copyright (C) 2018 MongoDB Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kSharding
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/db/s/config_server_op_observer.h"
+
+#include "mongo/db/s/config/sharding_catalog_manager.h"
+#include "mongo/s/catalog/type_config_version.h"
+#include "mongo/s/cluster_identity_loader.h"
+
+namespace mongo {
+
+ConfigServerOpObserver::ConfigServerOpObserver() = default;
+
+ConfigServerOpObserver::~ConfigServerOpObserver() = default;
+
+void ConfigServerOpObserver::onDelete(OperationContext* opCtx,
+                                      const NamespaceString& nss,
+                                      OptionalCollectionUUID uuid,
+                                      StmtId stmtId,
+                                      bool fromMigrate,
+                                      const boost::optional<BSONObj>& deletedDoc) {
+    if (nss == VersionType::ConfigNS) {
+        if (!repl::ReplicationCoordinator::get(opCtx)->getMemberState().rollback()) {
+            uasserted(40302, "cannot delete config.version document while in --configsvr mode");
+        } else {
+            // Throw out any cached information related to the cluster ID.
+            ShardingCatalogManager::get(opCtx)->discardCachedConfigDatabaseInitializationState();
+            ClusterIdentityLoader::get(opCtx)->discardCachedClusterId();
+        }
+    }
+}
+
+repl::OpTime ConfigServerOpObserver::onDropCollection(OperationContext* opCtx,
+                                                      const NamespaceString& collectionName,
+                                                      OptionalCollectionUUID uuid) {
+    if (collectionName == VersionType::ConfigNS) {
+        if (!repl::ReplicationCoordinator::get(opCtx)->getMemberState().rollback()) {
+            uasserted(40303, "cannot drop config.version document while in --configsvr mode");
+        } else {
+            // Throw out any cached information related to the cluster ID.
+            ShardingCatalogManager::get(opCtx)->discardCachedConfigDatabaseInitializationState();
+            ClusterIdentityLoader::get(opCtx)->discardCachedClusterId();
+        }
+    }
+
+    return {};
+}
+
+}  // namespace mongo
diff --git a/src/mongo/db/s/config_server_op_observer.h b/src/mongo/db/s/config_server_op_observer.h
new file mode 100644
index 00000000000..6bea48f4a11
--- /dev/null
+++ b/src/mongo/db/s/config_server_op_observer.h
@@ -0,0 +1,129 @@
+/**
+ *    Copyright (C) 2018 MongoDB Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#pragma once
+
+#include "mongo/base/disallow_copying.h"
+#include "mongo/db/op_observer.h"
+
+namespace mongo {
+
+/**
+ * OpObserver which is installed on the op observers chain when the server is running as a config
+ * server (--configsvr).
+ */
+class ConfigServerOpObserver final : public OpObserver {
+    MONGO_DISALLOW_COPYING(ConfigServerOpObserver);
+
+public:
+    ConfigServerOpObserver();
+    ~ConfigServerOpObserver();
+
+    void onCreateIndex(OperationContext* opCtx,
+                       const NamespaceString& nss,
+                       OptionalCollectionUUID uuid,
+                       BSONObj indexDoc,
+                       bool fromMigrate) override {}
+
+    void onInserts(OperationContext* opCtx,
+                   const NamespaceString& nss,
+                   OptionalCollectionUUID uuid,
+                   std::vector<InsertStatement>::const_iterator begin,
+                   std::vector<InsertStatement>::const_iterator end,
+                   bool fromMigrate) override {}
+
+    void onUpdate(OperationContext* opCtx, const OplogUpdateEntryArgs& args) override {}
+
+    void aboutToDelete(OperationContext* opCtx,
+                       const NamespaceString& nss,
+                       const BSONObj& doc) override {}
+
+    void onDelete(OperationContext* opCtx,
+                  const NamespaceString& nss,
+                  OptionalCollectionUUID uuid,
+                  StmtId stmtId,
+                  bool fromMigrate,
+                  const boost::optional<BSONObj>& deletedDoc) override;
+
+    void onInternalOpMessage(OperationContext* opCtx,
+                             const NamespaceString& nss,
+                             const boost::optional<UUID> uuid,
+                             const BSONObj& msgObj,
+                             const boost::optional<BSONObj> o2MsgObj) override {}
+
+    void onCreateCollection(OperationContext* opCtx,
+                            Collection* coll,
+                            const NamespaceString& collectionName,
+                            const CollectionOptions& options,
+                            const BSONObj& idIndex) override {}
+
+    void onCollMod(OperationContext* opCtx,
+                   const NamespaceString& nss,
+                   OptionalCollectionUUID uuid,
+                   const BSONObj& collModCmd,
+                   const CollectionOptions& oldCollOptions,
+                   boost::optional<TTLCollModInfo> ttlInfo) override {}
+
+    void onDropDatabase(OperationContext* opCtx, const std::string& dbName) override {}
+
+    repl::OpTime onDropCollection(OperationContext* opCtx,
+                                  const NamespaceString& collectionName,
+                                  OptionalCollectionUUID uuid) override;
+
+    void onDropIndex(OperationContext* opCtx,
+                     const NamespaceString& nss,
+                     OptionalCollectionUUID uuid,
+                     const std::string& indexName,
+                     const BSONObj& indexInfo) override {}
+
+    repl::OpTime onRenameCollection(OperationContext* opCtx,
+                                    const NamespaceString& fromCollection,
+                                    const NamespaceString& toCollection,
+                                    OptionalCollectionUUID uuid,
+                                    bool dropTarget,
+                                    OptionalCollectionUUID dropTargetUUID,
+                                    bool stayTemp) override {
+        return repl::OpTime();
+    }
+
+    void onApplyOps(OperationContext* opCtx,
+                    const std::string& dbName,
+                    const BSONObj& applyOpCmd) override {}
+
+    void onEmptyCapped(OperationContext* opCtx,
+                       const NamespaceString& collectionName,
+                       OptionalCollectionUUID uuid) override {}
+
+    void onTransactionCommit(OperationContext* opCtx) override {}
+
+    void onTransactionAbort(OperationContext* opCtx) override {}
+
+    void onReplicationRollback(OperationContext* opCtx, const RollbackObserverInfo& rbInfo) {}
+};
+
+}  // namespace mongo
diff --git a/src/mongo/db/s/metadata_manager_test.cpp b/src/mongo/db/s/metadata_manager_test.cpp
index 9c8e670dc2b..de7b0adce82 100644
--- a/src/mongo/db/s/metadata_manager_test.cpp
+++ b/src/mongo/db/s/metadata_manager_test.cpp
@@ -31,7 +31,6 @@
 #include <boost/optional.hpp>
 
 #include "mongo/bson/bsonobjbuilder.h"
-#include "mongo/client/remote_command_targeter_mock.h"
 #include "mongo/db/catalog_raii.h"
 #include "mongo/db/client.h"
 #include "mongo/db/dbdirectclient.h"
@@ -42,11 +41,10 @@
 #include "mongo/db/s/sharding_state.h"
 #include "mongo/db/server_options.h"
 #include "mongo/db/service_context.h"
-#include "mongo/db/service_context_d_test_fixture.h"
 #include "mongo/executor/task_executor.h"
 #include "mongo/s/catalog/type_chunk.h"
 #include "mongo/s/client/shard_registry.h"
-#include "mongo/s/sharding_mongod_test_fixture.h"
+#include "mongo/s/shard_server_test_fixture.h"
 #include "mongo/stdx/condition_variable.h"
 #include "mongo/stdx/memory.h"
 #include "mongo/unittest/unittest.h"
@@ -59,29 +57,17 @@ using unittest::assertGet;
 
 const NamespaceString kNss("TestDB", "TestColl");
 const std::string kPattern = "key";
-const BSONObj kShardKeyPatternBSON{BSON(kPattern << 1)};
-const KeyPattern kShardKeyPattern{kShardKeyPatternBSON};
+const KeyPattern kShardKeyPattern(BSON(kPattern << 1));
 const std::string kThisShard{"thisShard"};
 const std::string kOtherShard{"otherShard"};
-const HostAndPort dummyHost("dummy", 123);
 
-class MetadataManagerTest : public ShardingMongodTestFixture {
+class MetadataManagerTest : public ShardServerTestFixture {
 protected:
     void setUp() override {
-        ShardingMongodTestFixture::setUp();
-        serverGlobalParams.clusterRole = ClusterRole::ShardServer;
-        initializeGlobalShardingStateForMongodForTest(ConnectionString(dummyHost))
-            .transitional_ignore();
-
-        configTargeter()->setFindHostReturnValue(dummyHost);
-
+        ShardServerTestFixture::setUp();
         _manager = std::make_shared<MetadataManager>(getServiceContext(), kNss, executor());
     }
 
-    std::shared_ptr<RemoteCommandTargeterMock> configTargeter() const {
-        return RemoteCommandTargeterMock::get(shardRegistry()->getConfigShard()->getTargeter());
-    }
-
     static std::unique_ptr<CollectionMetadata> makeEmptyMetadata() {
         const OID epoch = OID::gen();
 
diff --git a/src/mongo/db/s/migration_chunk_cloner_source_legacy_test.cpp b/src/mongo/db/s/migration_chunk_cloner_source_legacy_test.cpp
index 34d91019d5e..49aec18b0fd 100644
--- a/src/mongo/db/s/migration_chunk_cloner_source_legacy_test.cpp
+++ b/src/mongo/db/s/migration_chunk_cloner_source_legacy_test.cpp
@@ -32,12 +32,11 @@
 #include "mongo/db/catalog_raii.h"
 #include "mongo/db/dbdirectclient.h"
 #include "mongo/db/namespace_string.h"
-#include "mongo/db/repl/replication_coordinator_mock.h"
 #include "mongo/db/s/migration_chunk_cloner_source_legacy.h"
 #include "mongo/s/catalog/sharding_catalog_client_mock.h"
 #include "mongo/s/catalog/type_shard.h"
 #include "mongo/s/client/shard_registry.h"
-#include "mongo/s/sharding_mongod_test_fixture.h"
+#include "mongo/s/shard_server_test_fixture.h"
 #include "mongo/unittest/unittest.h"
 
 namespace mongo {
@@ -64,23 +63,17 @@ const ConnectionString kRecipientConnStr =
                                      HostAndPort("RecipientHost2:1234"),
                                      HostAndPort("RecipientHost3:1234")});
 
-class MigrationChunkClonerSourceLegacyTest : public ShardingMongodTestFixture {
+class MigrationChunkClonerSourceLegacyTest : public ShardServerTestFixture {
 protected:
     void setUp() override {
-        serverGlobalParams.clusterRole = ClusterRole::ShardServer;
-        ShardingMongodTestFixture::setUp();
+        ShardServerTestFixture::setUp();
 
         // TODO: SERVER-26919 set the flag on the mock repl coordinator just for the window where it
         // actually needs to bypass the op observer.
         replicationCoordinator()->alwaysAllowWrites(true);
 
-        ASSERT_OK(initializeGlobalShardingStateForMongodForTest(kConfigConnStr));
-
         _client.emplace(operationContext());
 
-        RemoteCommandTargeterMock::get(shardRegistry()->getConfigShard()->getTargeter())
-            ->setConnectionStringReturnValue(kConfigConnStr);
-
         {
             auto donorShard = assertGet(
                 shardRegistry()->getShard(operationContext(), kDonorConnStr.getSetName()));
@@ -103,7 +96,7 @@ protected:
     void tearDown() override {
         _client.reset();
 
-        ShardingMongodTestFixture::tearDown();
+        ShardServerTestFixture::tearDown();
     }
 
     /**
diff --git a/src/mongo/db/s/session_catalog_migration_destination_test.cpp b/src/mongo/db/s/session_catalog_migration_destination_test.cpp
index 698f0464029..f1a2b422305 100644
--- a/src/mongo/db/s/session_catalog_migration_destination_test.cpp
+++ b/src/mongo/db/s/session_catalog_migration_destination_test.cpp
@@ -49,13 +49,12 @@
 #include "mongo/s/catalog/sharding_catalog_client_mock.h"
 #include "mongo/s/catalog/type_shard.h"
 #include "mongo/s/client/shard_registry.h"
-#include "mongo/s/sharding_mongod_test_fixture.h"
+#include "mongo/s/shard_server_test_fixture.h"
 #include "mongo/stdx/memory.h"
 #include "mongo/stdx/thread.h"
 #include "mongo/unittest/unittest.h"
 
 namespace mongo {
-
 namespace {
 
 using executor::RemoteCommandRequest;
@@ -113,16 +112,12 @@ repl::OplogEntry extractInnerOplog(const repl::OplogEntry& oplog) {
     return oplogStatus.getValue();
 }
 
-class SessionCatalogMigrationDestinationTest : public ShardingMongodTestFixture {
+class SessionCatalogMigrationDestinationTest : public ShardServerTestFixture {
 public:
     void setUp() override {
-        serverGlobalParams.clusterRole = ClusterRole::ShardServer;
-        ShardingMongodTestFixture::setUp();
-
-        ASSERT_OK(initializeGlobalShardingStateForMongodForTest(kConfigConnStr));
+        ShardServerTestFixture::setUp();
 
-        RemoteCommandTargeterMock::get(shardRegistry()->getConfigShard()->getTargeter())
-            ->setConnectionStringReturnValue(kConfigConnStr);
+        _migrationId = MigrationSessionId::generate("donor", "recipient");
 
         {
             auto donorShard = assertGet(
@@ -133,8 +128,6 @@ public:
                 ->setFindHostReturnValue(kDonorConnStr.getServers()[0]);
         }
 
-        _migrationId = MigrationSessionId::generate("donor", "recipient");
-
         SessionCatalog::create(getServiceContext());
         SessionCatalog::get(getServiceContext())->onStepUp(operationContext());
         LogicalSessionCache::set(getServiceContext(), stdx::make_unique<LogicalSessionCacheNoop>());
@@ -142,7 +135,7 @@ public:
 
     void tearDown() override {
         SessionCatalog::reset_forTest(getServiceContext());
-        ShardingMongodTestFixture::tearDown();
+        ShardServerTestFixture::tearDown();
     }
 
     void returnOplog(const std::vector<OplogEntry>& oplogList) {
diff --git a/src/mongo/db/s/shard_server_op_observer.cpp b/src/mongo/db/s/shard_server_op_observer.cpp
new file mode 100644
index 00000000000..6c0d678d85f
--- /dev/null
+++ b/src/mongo/db/s/shard_server_op_observer.cpp
@@ -0,0 +1,348 @@
+/**
+ *    Copyright (C) 2018 MongoDB Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kSharding
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/db/s/shard_server_op_observer.h"
+
+#include "mongo/bson/util/bson_extract.h"
+#include "mongo/db/catalog_raii.h"
+#include "mongo/db/s/collection_sharding_state.h"
+#include "mongo/db/s/shard_identity_rollback_notifier.h"
+#include "mongo/db/s/sharding_state.h"
+#include "mongo/db/s/type_shard_identity.h"
+#include "mongo/s/balancer_configuration.h"
+#include "mongo/s/catalog/type_shard_collection.h"
+#include "mongo/s/catalog_cache_loader.h"
+#include "mongo/s/grid.h"
+#include "mongo/util/log.h"
+
+namespace mongo {
+namespace {
+
+using DeleteState = CollectionShardingState::DeleteState;
+
+const OperationContext::Decoration<DeleteState> getDeleteState =
+    OperationContext::declareDecoration<DeleteState>();
+
+bool isStandaloneOrPrimary(OperationContext* opCtx) {
+    auto replCoord = repl::ReplicationCoordinator::get(opCtx);
+    const bool isReplSet =
+        replCoord->getReplicationMode() == repl::ReplicationCoordinator::modeReplSet;
+    return !isReplSet || (repl::ReplicationCoordinator::get(opCtx)->getMemberState() ==
+                          repl::MemberState::RS_PRIMARY);
+}
+
+/**
+ * Used to notify the catalog cache loader of a new collection version and invalidate the in-memory
+ * routing table cache once the oplog updates are committed and become visible.
+ */
+class CollectionVersionLogOpHandler final : public RecoveryUnit::Change {
+public:
+    CollectionVersionLogOpHandler(OperationContext* opCtx, const NamespaceString& nss)
+        : _opCtx(opCtx), _nss(nss) {}
+
+    void commit() override {
+        invariant(_opCtx->lockState()->isCollectionLockedForMode(_nss.ns(), MODE_IX));
+
+        CatalogCacheLoader::get(_opCtx).notifyOfCollectionVersionUpdate(_nss);
+
+        // This is a hack to get around CollectionShardingState::refreshMetadata() requiring the X
+        // lock: markNotShardedAtStepdown() doesn't have a lock check. Temporary measure until
+        // SERVER-31595 removes the X lock requirement.
+        CollectionShardingState::get(_opCtx, _nss)->markNotShardedAtStepdown();
+    }
+
+    void rollback() override {}
+
+private:
+    OperationContext* _opCtx;
+    const NamespaceString _nss;
+};
+
+/**
+ * Used to perform shard identity initialization once it is certain that the document is committed.
+ */
+class ShardIdentityLogOpHandler final : public RecoveryUnit::Change {
+public:
+    ShardIdentityLogOpHandler(OperationContext* opCtx, ShardIdentityType shardIdentity)
+        : _opCtx(opCtx), _shardIdentity(std::move(shardIdentity)) {}
+
+    void commit() override {
+        fassertNoTrace(
+            40071, ShardingState::get(_opCtx)->initializeFromShardIdentity(_opCtx, _shardIdentity));
+    }
+
+    void rollback() override {}
+
+private:
+    OperationContext* _opCtx;
+    const ShardIdentityType _shardIdentity;
+};
+
+/**
+ * Invalidates the in-memory routing table cache when a collection is dropped, so the next caller
+ * with routing information will provoke a routing table refresh and see the drop.
+ *
+ * The query parameter must contain an _id field that identifies which collections entry is being
+ * updated.
+ *
+ * This only runs on secondaries.
+ * The global exclusive lock is expected to be held by the caller.
+ */
+void onConfigDeleteInvalidateCachedMetadataAndNotify(OperationContext* opCtx,
+                                                     const BSONObj& query) {
+    // Notification of routing table changes are only needed on secondaries
+    if (isStandaloneOrPrimary(opCtx)) {
+        return;
+    }
+
+    // Extract which collection entry is being deleted from the _id field.
+    std::string deletedCollection;
+    fassert(40479,
+            bsonExtractStringField(query, ShardCollectionType::ns.name(), &deletedCollection));
+    const NamespaceString deletedNss(deletedCollection);
+
+    // Need the WUOW to retain the lock for CollectionVersionLogOpHandler::commit().
+    AutoGetCollection autoColl(opCtx, deletedNss, MODE_IX);
+
+    opCtx->recoveryUnit()->registerChange(new CollectionVersionLogOpHandler(opCtx, deletedNss));
+}
+
+/**
+ * Returns true if the total number of bytes on the specified chunk nears the max size of a shard.
+ */
+bool shouldSplitChunk(OperationContext* opCtx,
+                      const ShardKeyPattern& shardKeyPattern,
+                      const Chunk& chunk) {
+    const auto balancerConfig = Grid::get(opCtx)->getBalancerConfiguration();
+    invariant(balancerConfig);
+
+    const auto& keyPattern = shardKeyPattern.getKeyPattern();
+    const bool minIsInf = (0 == keyPattern.globalMin().woCompare(chunk.getMin()));
+    const bool maxIsInf = (0 == keyPattern.globalMax().woCompare(chunk.getMax()));
+
+    return chunk.shouldSplit(balancerConfig->getMaxChunkSizeBytes(), minIsInf, maxIsInf);
+}
+
+/**
+ * If the collection is sharded, finds the chunk that contains the specified document and increments
+ * the size tracked for that chunk by the specified amount of data written, in bytes. Returns the
+ * number of total bytes on that chunk after the data is written.
+ */
+void incrementChunkOnInsertOrUpdate(OperationContext* opCtx,
+                                    const ChunkManager& chunkManager,
+                                    const BSONObj& document,
+                                    long dataWritten) {
+    const auto& shardKeyPattern = chunkManager.getShardKeyPattern();
+
+    // Each inserted/updated document should contain the shard key. The only instance in which a
+    // document could not contain a shard key is if the insert/update is performed through mongod
+    // explicitly, as opposed to first routed through mongos.
+    BSONObj shardKey = shardKeyPattern.extractShardKeyFromDoc(document);
+    if (shardKey.woCompare(BSONObj()) == 0) {
+        warning() << "inserting document " << document.toString() << " without shard key pattern "
+                  << shardKeyPattern << " into a sharded collection";
+        return;
+    }
+
+    // Use the shard key to locate the chunk into which the document was updated, and increment the
+    // number of bytes tracked for the chunk.
+    //
+    // Note that we can assume the simple collation, because shard keys do not support non-simple
+    // collations.
+    auto chunk = chunkManager.findIntersectingChunkWithSimpleCollation(shardKey);
+    chunk->addBytesWritten(dataWritten);
+
+    // If the chunk becomes too large, then we call the ChunkSplitter to schedule a split. Then, we
+    // reset the tracking for that chunk to 0.
+    if (shouldSplitChunk(opCtx, shardKeyPattern, *chunk)) {
+        // TODO: call ChunkSplitter here
+        chunk->clearBytesWritten();
+    }
+}
+
+}  // namespace
+
+ShardServerOpObserver::ShardServerOpObserver() = default;
+
+ShardServerOpObserver::~ShardServerOpObserver() = default;
+
+void ShardServerOpObserver::onInserts(OperationContext* opCtx,
+                                      const NamespaceString& nss,
+                                      OptionalCollectionUUID uuid,
+                                      std::vector<InsertStatement>::const_iterator begin,
+                                      std::vector<InsertStatement>::const_iterator end,
+                                      bool fromMigrate) {
+    auto const css = CollectionShardingState::get(opCtx, nss);
+    const auto metadata = css->getMetadata();
+
+    for (auto it = begin; it != end; ++it) {
+        const auto& insertedDoc = it->doc;
+
+        if (nss == NamespaceString::kServerConfigurationNamespace) {
+            if (auto idElem = insertedDoc["_id"]) {
+                if (idElem.str() == ShardIdentityType::IdName) {
+                    auto shardIdentityDoc =
+                        uassertStatusOK(ShardIdentityType::fromBSON(insertedDoc));
+                    uassertStatusOK(shardIdentityDoc.validate());
+                    opCtx->recoveryUnit()->registerChange(
+                        new ShardIdentityLogOpHandler(opCtx, std::move(shardIdentityDoc)));
+                }
+            }
+        }
+
+        if (metadata) {
+            incrementChunkOnInsertOrUpdate(
+                opCtx, *metadata->getChunkManager(), insertedDoc, insertedDoc.objsize());
+        }
+    }
+}
+
+void ShardServerOpObserver::onUpdate(OperationContext* opCtx, const OplogUpdateEntryArgs& args) {
+    auto const css = CollectionShardingState::get(opCtx, args.nss);
+    const auto metadata = css->getMetadata();
+
+    if (args.nss.ns() == NamespaceString::kShardConfigCollectionsCollectionName) {
+        // Notification of routing table changes are only needed on secondaries
+        if (isStandaloneOrPrimary(opCtx)) {
+            return;
+        }
+
+        // This logic runs on updates to the shard's persisted cache of the config server's
+        // config.collections collection.
+        //
+        // If an update occurs to the 'lastRefreshedCollectionVersion' field it notifies the catalog
+        // cache loader of a new collection version and clears the routing table so the next caller
+        // with routing information will provoke a routing table refresh.
+        //
+        // When 'lastRefreshedCollectionVersion' is in 'update', it means that a chunk metadata
+        // refresh has finished being applied to the collection's locally persisted metadata store.
+        //
+        // If an update occurs to the 'enterCriticalSectionSignal' field, simply clear the routing
+        // table immediately. This will provoke the next secondary caller to refresh through the
+        // primary, blocking behind the critical section.
+
+        // Extract which user collection was updated
+        const auto updatedNss([&] {
+            std::string coll;
+            fassertStatusOK(
+                40477,
+                bsonExtractStringField(args.criteria, ShardCollectionType::ns.name(), &coll));
+            return NamespaceString(coll);
+        }());
+
+        // Parse the '$set' update
+        BSONElement setElement;
+        Status setStatus =
+            bsonExtractTypedField(args.update, StringData("$set"), Object, &setElement);
+        if (setStatus.isOK()) {
+            BSONObj setField = setElement.Obj();
+
+            // Need the WUOW to retain the lock for CollectionVersionLogOpHandler::commit()
+            AutoGetCollection autoColl(opCtx, updatedNss, MODE_IX);
+
+            if (setField.hasField(ShardCollectionType::lastRefreshedCollectionVersion.name())) {
+                opCtx->recoveryUnit()->registerChange(
+                    new CollectionVersionLogOpHandler(opCtx, updatedNss));
+            }
+
+            if (setField.hasField(ShardCollectionType::enterCriticalSectionCounter.name())) {
+                // This is a hack to get around CollectionShardingState::refreshMetadata() requiring
+                // the X lock: markNotShardedAtStepdown() doesn't have a lock check. Temporary
+                // measure until SERVER-31595 removes the X lock requirement.
+                CollectionShardingState::get(opCtx, updatedNss)->markNotShardedAtStepdown();
+            }
+        }
+    }
+
+    if (metadata) {
+        incrementChunkOnInsertOrUpdate(
+            opCtx, *metadata->getChunkManager(), args.updatedDoc, args.updatedDoc.objsize());
+    }
+}
+
+void ShardServerOpObserver::aboutToDelete(OperationContext* opCtx,
+                                          NamespaceString const& nss,
+                                          BSONObj const& doc) {
+    auto& deleteState = getDeleteState(opCtx);
+    auto* css = CollectionShardingState::get(opCtx, nss.ns());
+    deleteState = css->makeDeleteState(doc);
+}
+
+void ShardServerOpObserver::onDelete(OperationContext* opCtx,
+                                     const NamespaceString& nss,
+                                     OptionalCollectionUUID uuid,
+                                     StmtId stmtId,
+                                     bool fromMigrate,
+                                     const boost::optional<BSONObj>& deletedDoc) {
+    auto& deleteState = getDeleteState(opCtx);
+
+    if (nss.ns() == NamespaceString::kShardConfigCollectionsCollectionName) {
+        onConfigDeleteInvalidateCachedMetadataAndNotify(opCtx, deleteState.documentKey);
+    }
+
+    if (nss == NamespaceString::kServerConfigurationNamespace) {
+        if (auto idElem = deleteState.documentKey["_id"]) {
+            auto idStr = idElem.str();
+            if (idStr == ShardIdentityType::IdName) {
+                if (!repl::ReplicationCoordinator::get(opCtx)->getMemberState().rollback()) {
+                    uasserted(40070,
+                              "cannot delete shardIdentity document while in --shardsvr mode");
+                } else {
+                    warning() << "Shard identity document rolled back.  Will shut down after "
+                                 "finishing rollback.";
+                    ShardIdentityRollbackNotifier::get(opCtx)->recordThatRollbackHappened();
+                }
+            }
+        }
+    }
+}
+
+repl::OpTime ShardServerOpObserver::onDropCollection(OperationContext* opCtx,
+                                                     const NamespaceString& collectionName,
+                                                     OptionalCollectionUUID uuid) {
+    if (collectionName == NamespaceString::kServerConfigurationNamespace) {
+        // Dropping system collections is not allowed for end users
+        invariant(!opCtx->writesAreReplicated());
+        invariant(repl::ReplicationCoordinator::get(opCtx)->getMemberState().rollback());
+
+        // Can't confirm whether there was a ShardIdentity document or not yet, so assume there was
+        // one and shut down the process to clear the in-memory sharding state
+        warning() << "admin.system.version collection rolled back. Will shut down after finishing "
+                     "rollback";
+
+        ShardIdentityRollbackNotifier::get(opCtx)->recordThatRollbackHappened();
+    }
+
+    return {};
+}
+
+}  // namespace mongo
diff --git a/src/mongo/db/s/shard_server_op_observer.h b/src/mongo/db/s/shard_server_op_observer.h
new file mode 100644
index 00000000000..d15a7266668
--- /dev/null
+++ b/src/mongo/db/s/shard_server_op_observer.h
@@ -0,0 +1,129 @@
+/**
+ *    Copyright (C) 2018 MongoDB Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#pragma once
+
+#include "mongo/base/disallow_copying.h"
+#include "mongo/db/op_observer.h"
+
+namespace mongo {
+
+/**
+ * OpObserver which is installed on the op observers chain when the server is running as a shard
+ * server (--shardsvr).
+ */
+class ShardServerOpObserver final : public OpObserver {
+    MONGO_DISALLOW_COPYING(ShardServerOpObserver);
+
+public:
+    ShardServerOpObserver();
+    ~ShardServerOpObserver();
+
+    void onCreateIndex(OperationContext* opCtx,
+                       const NamespaceString& nss,
+                       OptionalCollectionUUID uuid,
+                       BSONObj indexDoc,
+                       bool fromMigrate) override {}
+
+    void onInserts(OperationContext* opCtx,
+                   const NamespaceString& nss,
+                   OptionalCollectionUUID uuid,
+                   std::vector<InsertStatement>::const_iterator begin,
+                   std::vector<InsertStatement>::const_iterator end,
+                   bool fromMigrate) override;
+
+    void onUpdate(OperationContext* opCtx, const OplogUpdateEntryArgs& args) override;
+
+    void aboutToDelete(OperationContext* opCtx,
+                       const NamespaceString& nss,
+                       const BSONObj& doc) override;
+
+    void onDelete(OperationContext* opCtx,
+                  const NamespaceString& nss,
+                  OptionalCollectionUUID uuid,
+                  StmtId stmtId,
+                  bool fromMigrate,
+                  const boost::optional<BSONObj>& deletedDoc) override;
+
+    void onInternalOpMessage(OperationContext* opCtx,
+                             const NamespaceString& nss,
+                             const boost::optional<UUID> uuid,
+                             const BSONObj& msgObj,
+                             const boost::optional<BSONObj> o2MsgObj) override {}
+
+    void onCreateCollection(OperationContext* opCtx,
+                            Collection* coll,
+                            const NamespaceString& collectionName,
+                            const CollectionOptions& options,
+                            const BSONObj& idIndex) override {}
+
+    void onCollMod(OperationContext* opCtx,
+                   const NamespaceString& nss,
+                   OptionalCollectionUUID uuid,
+                   const BSONObj& collModCmd,
+                   const CollectionOptions& oldCollOptions,
+                   boost::optional<TTLCollModInfo> ttlInfo) override {}
+
+    void onDropDatabase(OperationContext* opCtx, const std::string& dbName) override {}
+
+    repl::OpTime onDropCollection(OperationContext* opCtx,
+                                  const NamespaceString& collectionName,
+                                  OptionalCollectionUUID uuid) override;
+
+    void onDropIndex(OperationContext* opCtx,
+                     const NamespaceString& nss,
+                     OptionalCollectionUUID uuid,
+                     const std::string& indexName,
+                     const BSONObj& indexInfo) override {}
+
+    repl::OpTime onRenameCollection(OperationContext* opCtx,
+                                    const NamespaceString& fromCollection,
+                                    const NamespaceString& toCollection,
+                                    OptionalCollectionUUID uuid,
+                                    bool dropTarget,
+                                    OptionalCollectionUUID dropTargetUUID,
+                                    bool stayTemp) override {
+        return repl::OpTime();
+    }
+
+    void onApplyOps(OperationContext* opCtx,
+                    const std::string& dbName,
+                    const BSONObj& applyOpCmd) override {}
+
+    void onEmptyCapped(OperationContext* opCtx,
+                       const NamespaceString& collectionName,
+                       OptionalCollectionUUID uuid) override {}
+
+    void onTransactionCommit(OperationContext* opCtx) override {}
+
+    void onTransactionAbort(OperationContext* opCtx) override {}
+
+    void onReplicationRollback(OperationContext* opCtx, const RollbackObserverInfo& rbInfo) {}
+};
+
+}  // namespace mongo
diff --git a/src/mongo/db/s/sharding_state_test.cpp b/src/mongo/db/s/sharding_state_test.cpp
index 370a792d716..1b29fe5ceae 100644
--- a/src/mongo/db/s/sharding_state_test.cpp
+++ b/src/mongo/db/s/sharding_state_test.cpp
@@ -29,48 +29,37 @@
 #include "mongo/platform/basic.h"
 
 #include "mongo/client/remote_command_targeter_mock.h"
-#include "mongo/client/replica_set_monitor.h"
 #include "mongo/db/concurrency/d_concurrency.h"
 #include "mongo/db/dbdirectclient.h"
-#include "mongo/db/jsobj.h"
-#include "mongo/db/namespace_string.h"
+#include "mongo/db/op_observer_impl.h"
+#include "mongo/db/op_observer_registry.h"
 #include "mongo/db/repl/replication_coordinator_mock.h"
+#include "mongo/db/s/config_server_op_observer.h"
 #include "mongo/db/s/shard_server_catalog_cache_loader.h"
+#include "mongo/db/s/shard_server_op_observer.h"
 #include "mongo/db/s/sharding_state.h"
 #include "mongo/db/s/type_shard_identity.h"
 #include "mongo/db/server_options.h"
-#include "mongo/db/service_context_noop.h"
 #include "mongo/db/storage/storage_options.h"
 #include "mongo/s/catalog/dist_lock_manager_mock.h"
 #include "mongo/s/catalog/sharding_catalog_client_impl.h"
-#include "mongo/s/catalog_cache.h"
 #include "mongo/s/client/shard_registry.h"
 #include "mongo/s/config_server_catalog_cache_loader.h"
 #include "mongo/s/sharding_mongod_test_fixture.h"
 
 namespace mongo {
+namespace {
 
 using executor::RemoteCommandRequest;
 
-namespace {
+const std::string kShardName("a");
 
 class ShardingStateTest : public ShardingMongodTestFixture {
-public:
-    ShardingState* shardingState() {
-        return &_shardingState;
-    }
-
-    std::string shardName() const {
-        return _shardName.toString();
-    }
-
 protected:
     // Used to write to set up local collections before exercising server logic.
     std::unique_ptr<DBDirectClient> _dbDirectClient;
 
     void setUp() override {
-        _shardName = ShardId("a");
-
         serverGlobalParams.clusterRole = ClusterRole::None;
         ShardingMongodTestFixture::setUp();
 
@@ -88,8 +77,9 @@ protected:
             if (!status.isOK()) {
                 return status;
             }
-            // Set the ConnectionString return value on the mock targeter so that later calls to
-            // the targeter's getConnString() return the appropriate value.
+
+            // Set the ConnectionString return value on the mock targeter so that later calls to the
+            // targeter's getConnString() return the appropriate value
             auto configTargeter =
                 RemoteCommandTargeterMock::get(shardRegistry()->getConfigShard()->getTargeter());
             configTargeter->setConnectionStringReturnValue(configConnStr);
@@ -104,12 +94,9 @@ protected:
     void tearDown() override {
         _dbDirectClient.reset();
 
-        // Some test cases modify the readOnly value, but the teardown calls below depend on
-        // readOnly being false, so we reset the value here rather than in setUp().
+        // Restore the defaults before calling tearDown
         storageGlobalParams.readOnly = false;
-
-        // ShardingState initialize can modify ReplicaSetMonitor state.
-        ReplicaSetMonitor::cleanup();
+        serverGlobalParams.overrideShardIdentity = BSONObj();
 
         CatalogCacheLoader::clearForTests(getServiceContext());
 
@@ -127,27 +114,55 @@ protected:
         return stdx::make_unique<ShardingCatalogClientImpl>(std::move(distLockManager));
     }
 
-    std::unique_ptr<CatalogCache> makeCatalogCache() override {
-        return stdx::make_unique<CatalogCache>(CatalogCacheLoader::get(getServiceContext()));
+    ShardingState* shardingState() {
+        return &_shardingState;
     }
 
 private:
     ShardingState _shardingState;
-    ShardId _shardName;
+};
+
+/**
+ * This class emulates the server being started as a standalone node for the scope for which it is
+ * used
+ */
+class ScopedSetStandaloneMode {
+public:
+    ScopedSetStandaloneMode(ServiceContext* serviceContext) : _serviceContext(serviceContext) {
+        serverGlobalParams.clusterRole = ClusterRole::None;
+        _serviceContext->setOpObserver(stdx::make_unique<OpObserverRegistry>());
+    }
+
+    ~ScopedSetStandaloneMode() {
+        serverGlobalParams.clusterRole = ClusterRole::ShardServer;
+        auto makeOpObserver = [&] {
+            auto opObserver = stdx::make_unique<OpObserverRegistry>();
+            opObserver->addObserver(stdx::make_unique<OpObserverImpl>());
+            opObserver->addObserver(stdx::make_unique<ConfigServerOpObserver>());
+            opObserver->addObserver(stdx::make_unique<ShardServerOpObserver>());
+            return opObserver;
+        };
+
+        _serviceContext->setOpObserver(makeOpObserver());
+    }
+
+private:
+    ServiceContext* const _serviceContext;
 };
 
 TEST_F(ShardingStateTest, ValidShardIdentitySucceeds) {
+    // Must hold a lock to call initializeFromShardIdentity.
     Lock::GlobalWrite lk(operationContext());
 
     ShardIdentityType shardIdentity;
     shardIdentity.setConfigsvrConnString(
         ConnectionString(ConnectionString::SET, "a:1,b:2", "config"));
-    shardIdentity.setShardName(shardName());
+    shardIdentity.setShardName(kShardName);
     shardIdentity.setClusterId(OID::gen());
 
     ASSERT_OK(shardingState()->initializeFromShardIdentity(operationContext(), shardIdentity));
     ASSERT_TRUE(shardingState()->enabled());
-    ASSERT_EQ(shardName(), shardingState()->getShardName());
+    ASSERT_EQ(kShardName, shardingState()->getShardName());
     ASSERT_EQ("config/a:1,b:2", shardRegistry()->getConfigServerConnectionString().toString());
 }
 
@@ -158,7 +173,7 @@ TEST_F(ShardingStateTest, InitWhilePreviouslyInErrorStateWillStayInErrorState) {
     ShardIdentityType shardIdentity;
     shardIdentity.setConfigsvrConnString(
         ConnectionString(ConnectionString::SET, "a:1,b:2", "config"));
-    shardIdentity.setShardName(shardName());
+    shardIdentity.setShardName(kShardName);
     shardIdentity.setClusterId(OID::gen());
 
     shardingState()->setGlobalInitMethodForTest(
@@ -196,7 +211,7 @@ TEST_F(ShardingStateTest, InitializeAgainWithMatchingShardIdentitySucceeds) {
     ShardIdentityType shardIdentity;
     shardIdentity.setConfigsvrConnString(
         ConnectionString(ConnectionString::SET, "a:1,b:2", "config"));
-    shardIdentity.setShardName(shardName());
+    shardIdentity.setShardName(kShardName);
     shardIdentity.setClusterId(clusterID);
 
     ASSERT_OK(shardingState()->initializeFromShardIdentity(operationContext(), shardIdentity));
@@ -204,7 +219,7 @@ TEST_F(ShardingStateTest, InitializeAgainWithMatchingShardIdentitySucceeds) {
     ShardIdentityType shardIdentity2;
     shardIdentity2.setConfigsvrConnString(
         ConnectionString(ConnectionString::SET, "a:1,b:2", "config"));
-    shardIdentity2.setShardName(shardName());
+    shardIdentity2.setShardName(kShardName);
     shardIdentity2.setClusterId(clusterID);
 
     shardingState()->setGlobalInitMethodForTest(
@@ -215,7 +230,7 @@ TEST_F(ShardingStateTest, InitializeAgainWithMatchingShardIdentitySucceeds) {
     ASSERT_OK(shardingState()->initializeFromShardIdentity(operationContext(), shardIdentity2));
 
     ASSERT_TRUE(shardingState()->enabled());
-    ASSERT_EQ(shardName(), shardingState()->getShardName());
+    ASSERT_EQ(kShardName, shardingState()->getShardName());
     ASSERT_EQ("config/a:1,b:2", shardRegistry()->getConfigServerConnectionString().toString());
 }
 
@@ -227,7 +242,7 @@ TEST_F(ShardingStateTest, InitializeAgainWithSameReplSetNameSucceeds) {
     ShardIdentityType shardIdentity;
     shardIdentity.setConfigsvrConnString(
         ConnectionString(ConnectionString::SET, "a:1,b:2", "config"));
-    shardIdentity.setShardName(shardName());
+    shardIdentity.setShardName(kShardName);
     shardIdentity.setClusterId(clusterID);
 
     ASSERT_OK(shardingState()->initializeFromShardIdentity(operationContext(), shardIdentity));
@@ -235,7 +250,7 @@ TEST_F(ShardingStateTest, InitializeAgainWithSameReplSetNameSucceeds) {
     ShardIdentityType shardIdentity2;
     shardIdentity2.setConfigsvrConnString(
         ConnectionString(ConnectionString::SET, "b:2,c:3", "config"));
-    shardIdentity2.setShardName(shardName());
+    shardIdentity2.setShardName(kShardName);
     shardIdentity2.setClusterId(clusterID);
 
     shardingState()->setGlobalInitMethodForTest(
@@ -246,21 +261,18 @@ TEST_F(ShardingStateTest, InitializeAgainWithSameReplSetNameSucceeds) {
     ASSERT_OK(shardingState()->initializeFromShardIdentity(operationContext(), shardIdentity2));
 
     ASSERT_TRUE(shardingState()->enabled());
-    ASSERT_EQ(shardName(), shardingState()->getShardName());
+    ASSERT_EQ(kShardName, shardingState()->getShardName());
     ASSERT_EQ("config/a:1,b:2", shardRegistry()->getConfigServerConnectionString().toString());
 }
 
-// The below tests check for compatible startup parameters for --shardsvr, --overrideShardIdentity,
-// and queryableBackup (readOnly) mode.
+// The tests below check for different combinations of the compatible startup parameters for
+// --shardsvr, --overrideShardIdentity, and queryableBackup (readOnly) mode
 
 // readOnly and --shardsvr
 
 TEST_F(ShardingStateTest,
        InitializeShardingAwarenessIfNeededReadOnlyAndShardServerAndNoOverrideShardIdentity) {
     storageGlobalParams.readOnly = true;
-    serverGlobalParams.clusterRole = ClusterRole::ShardServer;
-    serverGlobalParams.overrideShardIdentity = BSONObj();
-
     auto swShardingInitialized =
         shardingState()->initializeShardingAwarenessIfNeeded(operationContext());
     ASSERT_EQUALS(ErrorCodes::InvalidOptions, swShardingInitialized.getStatus().code());
@@ -269,7 +281,6 @@ TEST_F(ShardingStateTest,
 TEST_F(ShardingStateTest,
        InitializeShardingAwarenessIfNeededReadOnlyAndShardServerAndInvalidOverrideShardIdentity) {
     storageGlobalParams.readOnly = true;
-    serverGlobalParams.clusterRole = ClusterRole::ShardServer;
     serverGlobalParams.overrideShardIdentity = BSON("_id"
                                                     << "shardIdentity"
                                                     << "configsvrConnectionString"
@@ -287,7 +298,7 @@ TEST_F(ShardingStateTest,
     ShardIdentityType shardIdentity;
     shardIdentity.setConfigsvrConnString(
         ConnectionString(ConnectionString::SET, "a:1,b:2", "config"));
-    shardIdentity.setShardName(shardName());
+    shardIdentity.setShardName(kShardName);
     shardIdentity.setClusterId(OID::gen());
     ASSERT_OK(shardIdentity.validate());
     serverGlobalParams.overrideShardIdentity = shardIdentity.toBSON();
@@ -304,7 +315,6 @@ TEST_F(ShardingStateTest,
        InitializeShardingAwarenessIfNeededReadOnlyAndNotShardServerAndNoOverrideShardIdentity) {
     storageGlobalParams.readOnly = true;
     serverGlobalParams.clusterRole = ClusterRole::None;
-    serverGlobalParams.overrideShardIdentity = BSONObj();
 
     auto swShardingInitialized =
         shardingState()->initializeShardingAwarenessIfNeeded(operationContext());
@@ -317,11 +327,11 @@ TEST_F(
     InitializeShardingAwarenessIfNeededReadOnlyAndNotShardServerAndInvalidOverrideShardIdentity) {
     storageGlobalParams.readOnly = true;
     serverGlobalParams.clusterRole = ClusterRole::None;
+
     serverGlobalParams.overrideShardIdentity = BSON("_id"
                                                     << "shardIdentity"
                                                     << "configsvrConnectionString"
                                                     << "invalid");
-
     auto swShardingInitialized =
         shardingState()->initializeShardingAwarenessIfNeeded(operationContext());
     ASSERT_EQUALS(ErrorCodes::InvalidOptions, swShardingInitialized.getStatus().code());
@@ -335,7 +345,7 @@ TEST_F(ShardingStateTest,
     ShardIdentityType shardIdentity;
     shardIdentity.setConfigsvrConnString(
         ConnectionString(ConnectionString::SET, "a:1,b:2", "config"));
-    shardIdentity.setShardName(shardName());
+    shardIdentity.setShardName(kShardName);
     shardIdentity.setClusterId(OID::gen());
     ASSERT_OK(shardIdentity.validate());
     serverGlobalParams.overrideShardIdentity = shardIdentity.toBSON();
@@ -349,7 +359,6 @@ TEST_F(ShardingStateTest,
 
 TEST_F(ShardingStateTest,
        InitializeShardingAwarenessIfNeededNotReadOnlyAndInvalidOverrideShardIdentity) {
-    storageGlobalParams.readOnly = false;
     serverGlobalParams.overrideShardIdentity = BSON("_id"
                                                     << "shardIdentity"
                                                     << "configsvrConnectionString"
@@ -370,12 +379,10 @@ TEST_F(ShardingStateTest,
 
 TEST_F(ShardingStateTest,
        InitializeShardingAwarenessIfNeededNotReadOnlyAndValidOverrideShardIdentity) {
-    storageGlobalParams.readOnly = false;
-
     ShardIdentityType shardIdentity;
     shardIdentity.setConfigsvrConnString(
         ConnectionString(ConnectionString::SET, "a:1,b:2", "config"));
-    shardIdentity.setShardName(shardName());
+    shardIdentity.setShardName(kShardName);
     shardIdentity.setClusterId(OID::gen());
     ASSERT_OK(shardIdentity.validate());
     serverGlobalParams.overrideShardIdentity = shardIdentity.toBSON();
@@ -397,9 +404,6 @@ TEST_F(ShardingStateTest,
 
 TEST_F(ShardingStateTest,
        InitializeShardingAwarenessIfNeededNotReadOnlyAndShardServerAndNoShardIdentity) {
-    storageGlobalParams.readOnly = false;
-    serverGlobalParams.clusterRole = ClusterRole::ShardServer;
-    serverGlobalParams.overrideShardIdentity = BSONObj();
     auto swShardingInitialized =
         shardingState()->initializeShardingAwarenessIfNeeded(operationContext());
     ASSERT_OK(swShardingInitialized);
@@ -408,23 +412,19 @@ TEST_F(ShardingStateTest,
 
 TEST_F(ShardingStateTest,
        InitializeShardingAwarenessIfNeededNotReadOnlyAndShardServerAndInvalidShardIdentity) {
-
-    ASSERT_OK(replicationCoordinator()->setFollowerMode(repl::MemberState::RS_PRIMARY));
-
-    // Insert the shardIdentity doc to disk before setting the clusterRole, since if the clusterRole
-    // is ShardServer, the OpObserver for inserts will prevent the insert from occurring, since the
-    // shardIdentity doc is invalid.
-    serverGlobalParams.clusterRole = ClusterRole::None;
-    BSONObj invalidShardIdentity = BSON("_id"
-                                        << "shardIdentity"
-                                        << "configsvrConnectionString"
-                                        << "invalid");
-    _dbDirectClient->insert(NamespaceString::kServerConfigurationNamespace.toString(),
-                            invalidShardIdentity);
-
-    storageGlobalParams.readOnly = false;
-    serverGlobalParams.clusterRole = ClusterRole::ShardServer;
-    serverGlobalParams.overrideShardIdentity = BSONObj();
+    // Insert the shardIdentity doc to disk while pretending that we are in "standalone" mode,
+    // otherwise OpObserver for inserts will prevent the insert from occurring because the
+    // shardIdentity doc is invalid
+    {
+        ScopedSetStandaloneMode standalone(getServiceContext());
+
+        BSONObj invalidShardIdentity = BSON("_id"
+                                            << "shardIdentity"
+                                            << "configsvrConnectionString"
+                                            << "invalid");
+        _dbDirectClient->insert(NamespaceString::kServerConfigurationNamespace.toString(),
+                                invalidShardIdentity);
+    }
 
     auto swShardingInitialized =
         shardingState()->initializeShardingAwarenessIfNeeded(operationContext());
@@ -434,28 +434,25 @@ TEST_F(ShardingStateTest,
 
 TEST_F(ShardingStateTest,
        InitializeShardingAwarenessIfNeededNotReadOnlyAndShardServerAndValidShardIdentity) {
-
-    ASSERT_OK(replicationCoordinator()->setFollowerMode(repl::MemberState::RS_PRIMARY));
-
-    // Insert the shardIdentity doc to disk before setting the clusterRole, since if the clusterRole
-    // is ShardServer, the OpObserver for inserts will trigger sharding initialization from the
-    // inserted doc.
-    serverGlobalParams.clusterRole = ClusterRole::None;
-
-    ShardIdentityType shardIdentity;
-    shardIdentity.setConfigsvrConnString(
-        ConnectionString(ConnectionString::SET, "a:1,b:2", "config"));
-    shardIdentity.setShardName(shardName());
-    shardIdentity.setClusterId(OID::gen());
-    ASSERT_OK(shardIdentity.validate());
-    BSONObj validShardIdentity = shardIdentity.toBSON();
-
-    _dbDirectClient->insert(NamespaceString::kServerConfigurationNamespace.toString(),
-                            validShardIdentity);
-
-    storageGlobalParams.readOnly = false;
-    serverGlobalParams.clusterRole = ClusterRole::ShardServer;
-    serverGlobalParams.overrideShardIdentity = BSONObj();
+    // Insert the shardIdentity doc to disk while pretending that we are in "standalone" mode,
+    // otherwise OpObserver for inserts will prevent the insert from occurring because the
+    // shardIdentity doc is invalid
+    {
+        ScopedSetStandaloneMode standalone(getServiceContext());
+
+        BSONObj validShardIdentity = [&] {
+            ShardIdentityType shardIdentity;
+            shardIdentity.setConfigsvrConnString(
+                ConnectionString(ConnectionString::SET, "a:1,b:2", "config"));
+            shardIdentity.setShardName(kShardName);
+            shardIdentity.setClusterId(OID::gen());
+            ASSERT_OK(shardIdentity.validate());
+            return shardIdentity.toBSON();
+        }();
+
+        _dbDirectClient->insert(NamespaceString::kServerConfigurationNamespace.toString(),
+                                validShardIdentity);
+    }
 
     auto swShardingInitialized =
         shardingState()->initializeShardingAwarenessIfNeeded(operationContext());
@@ -467,9 +464,8 @@ TEST_F(ShardingStateTest,
 
 TEST_F(ShardingStateTest,
        InitializeShardingAwarenessIfNeededNotReadOnlyAndNotShardServerAndNoShardIdentity) {
-    storageGlobalParams.readOnly = false;
-    serverGlobalParams.clusterRole = ClusterRole::None;
-    serverGlobalParams.overrideShardIdentity = BSONObj();
+    ScopedSetStandaloneMode standalone(getServiceContext());
+
     auto swShardingInitialized =
         shardingState()->initializeShardingAwarenessIfNeeded(operationContext());
     ASSERT_OK(swShardingInitialized);
@@ -478,18 +474,16 @@ TEST_F(ShardingStateTest,
 
 TEST_F(ShardingStateTest,
        InitializeShardingAwarenessIfNeededNotReadOnlyAndNotShardServerAndInvalidShardIdentity) {
+    ScopedSetStandaloneMode standalone(getServiceContext());
+
     _dbDirectClient->insert(NamespaceString::kServerConfigurationNamespace.toString(),
                             BSON("_id"
                                  << "shardIdentity"
                                  << "configsvrConnectionString"
                                  << "invalid"));
 
-    storageGlobalParams.readOnly = false;
-    serverGlobalParams.clusterRole = ClusterRole::None;
-    serverGlobalParams.overrideShardIdentity = BSONObj();
-
-    // The shardIdentity doc on disk, even if invalid, is ignored if ClusterRole is None.
-    // This is to allow fixing the shardIdentity doc by starting without --shardsvr.
+    // The shardIdentity doc on disk, even if invalid, is ignored if the ClusterRole is None. This
+    // is to allow fixing the shardIdentity doc by starting without --shardsvr.
     auto swShardingInitialized =
         shardingState()->initializeShardingAwarenessIfNeeded(operationContext());
     ASSERT_OK(swShardingInitialized);
@@ -498,17 +492,17 @@ TEST_F(ShardingStateTest,
 
 TEST_F(ShardingStateTest,
        InitializeShardingAwarenessIfNeededNotReadOnlyAndNotShardServerAndValidShardIdentity) {
-    storageGlobalParams.readOnly = false;
-    serverGlobalParams.clusterRole = ClusterRole::None;
-    serverGlobalParams.overrideShardIdentity = BSONObj();
-
-    ShardIdentityType shardIdentity;
-    shardIdentity.setConfigsvrConnString(
-        ConnectionString(ConnectionString::SET, "a:1,b:2", "config"));
-    shardIdentity.setShardName(shardName());
-    shardIdentity.setClusterId(OID::gen());
-    ASSERT_OK(shardIdentity.validate());
-    BSONObj validShardIdentity = shardIdentity.toBSON();
+    ScopedSetStandaloneMode standalone(getServiceContext());
+
+    BSONObj validShardIdentity = [&] {
+        ShardIdentityType shardIdentity;
+        shardIdentity.setConfigsvrConnString(
+            ConnectionString(ConnectionString::SET, "a:1,b:2", "config"));
+        shardIdentity.setShardName(kShardName);
+        shardIdentity.setClusterId(OID::gen());
+        ASSERT_OK(shardIdentity.validate());
+        return shardIdentity.toBSON();
+    }();
 
     _dbDirectClient->insert(NamespaceString::kServerConfigurationNamespace.toString(),
                             validShardIdentity);
diff --git a/src/mongo/db/service_context_d_test_fixture.cpp b/src/mongo/db/service_context_d_test_fixture.cpp
index cc1401b6517..4f69e5eb7b9 100644
--- a/src/mongo/db/service_context_d_test_fixture.cpp
+++ b/src/mongo/db/service_context_d_test_fixture.cpp
@@ -41,8 +41,6 @@
 #include "mongo/db/logical_clock.h"
 #include "mongo/db/op_observer_noop.h"
 #include "mongo/db/op_observer_registry.h"
-#include "mongo/db/operation_context.h"
-#include "mongo/db/service_context.h"
 #include "mongo/db/service_context_d.h"
 #include "mongo/db/storage/storage_options.h"
 #include "mongo/stdx/memory.h"
diff --git a/src/mongo/db/service_context_d_test_fixture.h b/src/mongo/db/service_context_d_test_fixture.h
index 402a1837724..35932b64814 100644
--- a/src/mongo/db/service_context_d_test_fixture.h
+++ b/src/mongo/db/service_context_d_test_fixture.h
@@ -28,13 +28,12 @@
 
 #pragma once
 
+#include "mongo/db/operation_context.h"
+#include "mongo/db/service_context.h"
 #include "mongo/unittest/unittest.h"
 
 namespace mongo {
 
-class ServiceContext;
-class OperationContext;
-
 /**
  * Test fixture class for tests that use either the "ephemeralForTest" or "devnull" storage engines.
  */