MongoDB Sharded Cluster Quickstart

Set up a minimal MongoDB sharded cluster with a replication factor of 2 using docker-compose (development only).

Components

• Config Server (3-member replica set): config01,config02,config03
• 3 Shards (each a 2 member replica set):
  • shard01a,shard01b
  • shard02a,shard02b
  • shard03a,shard03b
• 1 Router (mongos): router

Initialization

docker-compose up -d

Initialize the config server, shards, and router:

sh init.sh

This script has a sleep 20 to wait for the config server and shards to elect the primaries of their replica sets respectively before initializing the router.

Create the first user admin on database admin and verify the status of the sharded cluster:

docker-compose exec -it router mongosh --host localhost --port 27017
mongos> admin = db.getSiblingDB("admin")
mongos> admin.createUser(
  {
    user: "admin",
    pwd:  "mypass",
    roles: [ 
      { role: "userAdminAnyDatabase", db: "admin" },
      { role: "clusterAdmin", db: "admin" }
    ]
  }
)
mongos> admin.auth('admin', 'mypass')
mongos> sh.status()
shardingVersion
{
  _id: 1,
  minCompatibleVersion: 5,
  currentVersion: 6,
  clusterId: ObjectId("636276b5aabddd36d3cee9e6")
}
---
shards
[
  {
    _id: 'shard01',
    host: 'shard01/shard01a:27018,shard01b:27018',
    state: 1,
    topologyTime: Timestamp({ t: 1667397315, i: 4 })
  },
  {
    _id: 'shard02',
    host: 'shard02/shard02a:27019,shard02b:27019',
    state: 1,
    topologyTime: Timestamp({ t: 1667397315, i: 12 })
  },
  {
    _id: 'shard03',
    host: 'shard03/shard03a:27020,shard03b:27020',
    state: 1,
    topologyTime: Timestamp({ t: 1667397315, i: 17 })
  }
]
---
active mongoses
[ { '6.0.2': 1 } ]
---
autosplit
{ 'Currently enabled': 'yes' }
---
balancer
{
  'Currently enabled': 'yes',
  'Currently running': 'no',
  'Failed balancer rounds in last 5 attempts': 0,
  'Migration Results for the last 24 hours': { '247': 'Success' }
}
---
databases
[
  {
    database: { _id: 'config', primary: 'config', partitioned: true },
    collections: {
      'config.system.sessions': {
        shardKey: { _id: 1 },
        unique: false,
        balancing: true,
        chunkMetadata: [
          { shard: 'shard01', nChunks: 777 },
          { shard: 'shard02', nChunks: 124 },
          { shard: 'shard03', nChunks: 123 }
        ],
        chunks: [
          'too many chunks to print, use verbose if you want to force print'
        ],
        tags: []
      }
    }
  }
]

Test client connection with user authentication:

docker-compose exec -it router mongosh --host localhost --port 27017 -u admin -p mypass --authenticationDatabase "admin"

For programming clients, you can use the following connection string URI:

mongodb://admin:mypass@router:27017/?authSource=admin