SERVER-19524 Add configServer field to replica set configurations

1 files changed, 33 insertions, 2 deletions

diff --git a/src/mongo/db/repl/replica_set_config.cpp b/src/mongo/db/repl/replica_set_config.cpp
index 70bc1156470..1f394956f91 100644
--- a/src/mongo/db/repl/replica_set_config.cpp
+++ b/src/mongo/db/repl/replica_set_config.cpp
@@ -45,6 +45,7 @@ const size_t ReplicaSetConfig::kMaxMembers;
 const size_t ReplicaSetConfig::kMaxVotingMembers;
 #endif
 
+const std::string ReplicaSetConfig::kConfigServerFieldName = "configServer";
 const std::string ReplicaSetConfig::kVersionFieldName = "version";
 const std::string ReplicaSetConfig::kMajorityWriteConcernModeName = "$majority";
 const Seconds ReplicaSetConfig::kDefaultHeartbeatTimeoutPeriod(10);
@@ -61,7 +62,8 @@ const std::string kLegalConfigTopFieldNames[] = {kIdFieldName,
                                                  ReplicaSetConfig::kVersionFieldName,
                                                  kMembersFieldName,
                                                  kSettingsFieldName,
-                                                 kProtocolVersionFieldName};
+                                                 kProtocolVersionFieldName,
+                                                 ReplicaSetConfig::kConfigServerFieldName};
 
 const std::string kHeartbeatTimeoutFieldName = "heartbeatTimeoutSecs";
 const std::string kChainingAllowedFieldName = "chainingAllowed";
@@ -71,7 +73,10 @@ const std::string kGetLastErrorModesFieldName = "getLastErrorModes";
 }  // namespace
 
 ReplicaSetConfig::ReplicaSetConfig()
-    : _isInitialized(false), _heartbeatTimeoutPeriod(0), _protocolVersion(0) {}
+    : _isInitialized(false),
+      _heartbeatTimeoutPeriod(0),
+      _protocolVersion(0),
+      _configServer(false) {}
 
 Status ReplicaSetConfig::initialize(const BSONObj& cfg) {
     _isInitialized = false;
@@ -118,6 +123,14 @@ Status ReplicaSetConfig::initialize(const BSONObj& cfg) {
     }
 
     //
+    // Parse configServer
+    //
+    status = bsonExtractBooleanFieldWithDefault(cfg, kConfigServerFieldName, false, &_configServer);
+    if (!status.isOK()) {
+        return status;
+    }
+
+    //
     // Parse settings
     //
     BSONElement settingsElement;
@@ -364,6 +377,19 @@ Status ReplicaSetConfig::validate() const {
                                     << _protocolVersion << " is out of range");
     }
 
+    if (_configServer) {
+        if (arbiterCount > 0) {
+            return Status(ErrorCodes::BadValue,
+                          "Arbiters are not allowed in replica set configurations being used for "
+                          "config servers");
+        }
+        if (_protocolVersion < 1) {
+            return Status(ErrorCodes::BadValue,
+                          "Replica sets must have protocol version of at least 1 in order to be "
+                          "used as sharding config servers");
+        }
+    }
+
     return Status::OK();
 }
 
@@ -511,6 +537,11 @@ BSONObj ReplicaSetConfig::toBSON() const {
     BSONObjBuilder configBuilder;
     configBuilder.append(kIdFieldName, _replSetName);
     configBuilder.appendIntOrLL(kVersionFieldName, _version);
+    if (_protocolVersion > 0) {
+        // Don't include "configServer" field if protocol version is less than 1 to preserve
+        // backwards compatibility
+        configBuilder.append(kConfigServerFieldName, _configServer);
+    }
 
     BSONArrayBuilder members(configBuilder.subarrayStart(kMembersFieldName));
     for (MemberIterator mem = membersBegin(); mem != membersEnd(); mem++) {