SERVER-8117: listDatabases - config/admin db should come from config servers

jstests/sharding/listDatabases.js

@@ -0,0 +1,46 @@
+// tests that listDatabases doesn't show config db on a shard, even if it is there
+
+var test = new ShardingTest({shards: 1, mongos: 1, config: 1, other: {chunksize:1, separateConfig:true}})
+
+var mongos = test.s0
+var mongod = test.shard0;
+
+//grab the config db instance by name
+var getDBSection = function (dbsArray, dbToFind) {
+    for(var pos in dbsArray) {
+        if (dbsArray[pos].name && dbsArray[pos].name === dbToFind)
+            return dbsArray[pos];
+    }
+    return null;
+}
+
+mongos.getDB("blah").foo.insert({_id:1})
+mongos.getDB("foo").foo.insert({_id:1})
+mongos.getDB("raw").foo.insert({_id:1})
+//wait for writes to finish
+mongos.getDB("raw").getLastError()
+
+//verify that the config db is not on a shard
+var res = mongos.adminCommand("listDatabases");
+var dbArray = res.databases;
+assert(getDBSection(dbArray, "config"), "config db not found! 1")
+assert(!getDBSection(dbArray, "config").shards, "config db is on a shard! 1")
+
+//add doc in config/admin db on the shard
+mongod.getDB("config").foo.insert({_id:1})
+mongod.getDB("admin").foo.insert({_id:1})
+
+//add doc in admin db (via mongos)
+mongos.getDB("admin").foo.insert({_id:1})
+
+//verify that the config db is not on a shard
+var res = mongos.adminCommand("listDatabases");
+var dbArray = res.databases;
+//check config db
+assert(getDBSection(dbArray, "config"), "config db not found! 2")
+assert(!getDBSection(dbArray, "config").shards, "config db is on a shard! 2")
+//check admin db
+assert(getDBSection(dbArray, "admin"), "admin db not found! 2")
+assert(!getDBSection(dbArray, "admin").shards, "admin db is on a shard! 2")
+
+test.stop()

src/mongo/s/commands_admin.cpp

@@ -1283,6 +1283,11 @@ namespace mongo {
                     continue;
                 }
 
+                if ( name == "config" || name == "admin" ) {
+                    //always get this from the config servers
+                    continue;
+                }
+
                 long long size = i->second;
                 totalSize += size;
 
@@ -1295,7 +1300,7 @@ namespace mongo {
                 bb.append( temp.obj() );
             }
             
-            if ( sizes.find( "config" ) == sizes.end() ){
+            { // get config db from the config servers (first one)
                 scoped_ptr<ScopedDbConnection> conn(
                         ScopedDbConnection::getInternalScopedDbConnection( configServer.getPrimary()
                                                                            .getConnString() ) );
@@ -1316,6 +1321,27 @@ namespace mongo {
                 conn->done();
             }
 
+            { // get admin db from the config servers (first one)
+                scoped_ptr<ScopedDbConnection> conn(
+                        ScopedDbConnection::getInternalScopedDbConnection(
+                                configServer.getPrimary().getConnString(), 30));
+                BSONObj x;
+                if ( conn->get()->simpleCommand( "admin" , &x , "dbstats" ) ){
+                    BSONObjBuilder b;
+                    b.append( "name" , "admin" );
+                    b.appendBool( "empty" , false );
+                    if ( x["fileSize"].type() )
+                        b.appendAs( x["fileSize"] , "sizeOnDisk" );
+                    else
+                        b.append( "sizeOnDisk" , 1 );
+                    bb.append( b.obj() );
+                }
+                else {
+                    bb.append( BSON( "name" << "admin" ) );
+                }
+                conn->done();
+            }
+
             bb.done();
 
             result.appendNumber( "totalSize" , totalSize );