SERVER-36380 Add --outputConfig command line option

5 files changed, 140 insertions, 0 deletions

diff --git a/src/mongo/db/server_options_server_helpers.cpp b/src/mongo/db/server_options_server_helpers.cpp
index e5b59443cbc..9342ae91302 100644
--- a/src/mongo/db/server_options_server_helpers.cpp
+++ b/src/mongo/db/server_options_server_helpers.cpp
@@ -88,6 +88,13 @@ Status addGeneralServerOptions(moe::OptionSection* options) {
             "config", "config,f", moe::String, "configuration file specifying additional options")
         .setSources(moe::SourceAllLegacy);
 
+    options
+        ->addOptionChaining("outputConfig",
+                            "outputConfig",
+                            moe::Switch,
+                            "Display the resolved configuration and exit")
+        .setSources(moe::SourceCommandLine)
+        .hidden();
 
     options
         ->addOptionChaining(
diff --git a/src/mongo/util/options_parser/environment.cpp b/src/mongo/util/options_parser/environment.cpp
index 021fedec677..08f68009da1 100644
--- a/src/mongo/util/options_parser/environment.cpp
+++ b/src/mongo/util/options_parser/environment.cpp
@@ -28,6 +28,7 @@
 #include "mongo/util/options_parser/environment.h"
 
 #include <iostream>
+#include <yaml-cpp/yaml.h>
 
 #include "mongo/bson/util/builder.h"
 #include "mongo/db/jsobj.h"
@@ -357,6 +358,54 @@ Status valueMapToBSON(const std::map<Key, Value>& params,
     }
     return Status::OK();
 }
+
+void buildYAMLNode(YAML::Emitter& out, const BSONObj& in, bool isMap = true) {
+    if (isMap) {
+        out << YAML::BeginMap;
+    } else {
+        out << YAML::BeginSeq;
+    }
+
+    for (const auto& elem : in) {
+        if (isMap) {
+            out << YAML::Key << elem.fieldName();
+            out << YAML::Value;
+        }
+        switch (elem.type()) {
+            case BSONType::Bool:
+                out << elem.Bool();
+                break;
+            case BSONType::NumberInt:
+                out << elem.Int();
+                break;
+            case BSONType::NumberLong:
+                out << elem.Long();
+                break;
+            case BSONType::NumberDouble:
+                out << elem.Double();
+                break;
+            case BSONType::String:
+                out << elem.String();
+                break;
+            case BSONType::Array:
+                buildYAMLNode(out, elem.Obj(), false);
+                break;
+            case BSONType::Object:
+                buildYAMLNode(out, elem.Obj(), true);
+                break;
+            default:
+                // Other types should not be produced by MOE.
+                uasserted(ErrorCodes::BadValue,
+                          str::stream() << "Invalid type encountered in config: " << elem.type());
+        }
+    }
+
+    if (isMap) {
+        out << YAML::EndMap;
+    } else {
+        out << YAML::EndSeq;
+    }
+}
 }  // namespace
 
 BSONObj Environment::toBSON() const {
@@ -368,5 +417,12 @@ BSONObj Environment::toBSON() const {
     return builder.obj();
 }
 
+std::string Environment::toYAML() const {
+    auto bson = toBSON();
+    YAML::Emitter root;
+    buildYAMLNode(root, bson);
+    return root.c_str();
+}
+
 }  // namespace optionenvironment
 }  // namespace mongo
diff --git a/src/mongo/util/options_parser/environment.h b/src/mongo/util/options_parser/environment.h
index 624e711b30d..d7791eabf44 100644
--- a/src/mongo/util/options_parser/environment.h
+++ b/src/mongo/util/options_parser/environment.h
@@ -211,6 +211,11 @@ public:
      */
     BSONObj toBSON() const;
 
+    /**
+     * Produce serialized YAML.
+     */
+    std::string toYAML() const;
+
     /* Debugging */
     void dump() const;
 
diff --git a/src/mongo/util/options_parser/options_parser_init.cpp b/src/mongo/util/options_parser/options_parser_init.cpp
index f75c98c603a..1bf0e8851c4 100644
--- a/src/mongo/util/options_parser/options_parser_init.cpp
+++ b/src/mongo/util/options_parser/options_parser_init.cpp
@@ -49,6 +49,17 @@ MONGO_STARTUP_OPTIONS_PARSE(StartupOptions)(InitializerContext* context) {
         std::cerr << "try '" << context->args()[0] << " --help' for more information" << std::endl;
         quickExit(EXIT_BADOPTIONS);
     }
+    if (startupOptionsParsed.count("outputConfig")) {
+        bool output = false;
+        auto status = startupOptionsParsed.get(Key("outputConfig"), &output);
+        if (!status.isOK()) {
+            return status;
+        }
+        if (output) {
+            std::cout << startupOptionsParsed.toYAML() << std::endl;
+            quickExit(EXIT_CLEAN);
+        }
+    }
     return Status::OK();
 }
 
diff --git a/src/mongo/util/options_parser/options_parser_test.cpp b/src/mongo/util/options_parser/options_parser_test.cpp
index cec439a5626..beeea6c6448 100644
--- a/src/mongo/util/options_parser/options_parser_test.cpp
+++ b/src/mongo/util/options_parser/options_parser_test.cpp
@@ -4624,6 +4624,67 @@ TEST(NumericalBaseParsing, YAMLConfigFile) {
     ASSERT_EQUALS(unsignedVal, 0x10U);
 }
 
+TEST(YAMLConfigFile, OutputConfig) {
+    moe::OptionSection options;
+    options.addOptionChaining("cacheSize", "cacheSize", moe::Long, "");
+    options.addOptionChaining("command", "command", moe::StringVector, "");
+    options.addOptionChaining("config", "config", moe::String, "");
+    options.addOptionChaining("math.pi", "pi", moe::Double, "");
+    options.addOptionChaining("net.port", "port", moe::Int, "");
+    options.addOptionChaining("net.bindIp", "bind_ip", moe::String, "");
+    options.addOptionChaining("net.bindIpAll", "bind_ip_all", moe::Switch, "");
+    options.addOptionChaining("security.javascriptEnabled", "javascriptEnabled", moe::Bool, "");
+    options.addOptionChaining("setParameter", "setParameter", moe::StringMap, "");
+    options.addOptionChaining("systemLog.path", "logPath", moe::String, "");
+
+    OptionsParserTester parser;
+    parser.setConfig("config.yaml",
+                     "systemLog: { path: /tmp/mongod.log }\n"
+                     "command: [ mongo, mongod, mongos ]");
+
+    const std::vector<std::string> argv = {
+        "binaryname",
+        "--port",
+        "31337",
+        "--bind_ip",
+        "127.0.0.1,::1",
+        "--bind_ip_all",
+        "--setParameter",
+        "scramSHAIterationCount=12345",
+        "--javascriptEnabled",
+        "false",
+        "--cacheSize",
+        "12345",
+        "--pi",
+        "3.14159265",
+        "--config",
+        "config.yaml",
+    };
+
+    std::map<std::string, std::string> env_map;
+    moe::Environment env;
+    ASSERT_OK(parser.run(options, argv, env_map, &env));
+    ASSERT_EQ(env.toYAML(),
+              "cacheSize: 12345\n"
+              "command:\n"
+              "  - mongo\n"
+              "  - mongod\n"
+              "  - mongos\n"
+              "config: config.yaml\n"
+              "math:\n"
+              "  pi: 3.14159265\n"
+              "net:\n"
+              "  bindIp: 127.0.0.1,::1\n"
+              "  bindIpAll: true\n"
+              "  port: 31337\n"
+              "security:\n"
+              "  javascriptEnabled: false\n"
+              "setParameter:\n"
+              "  scramSHAIterationCount: 12345\n"
+              "systemLog:\n"
+              "  path: /tmp/mongod.log");
+}
+
 void TestFile(std::vector<unsigned char> contents, bool valid) {
     mongo::unittest::TempDir tempdir("options_testpath");
     boost::filesystem::path p(tempdir.path());