Mongo Sharded Cluster with Docker Compose

Mongo Components

• Config Server (3 member replica set): cfgsvr1, cfgsvr2, cfgsvr3
• 3 Shards (each a 3 member replica set):
  • shard1svr1, shard1svr2, shard1svr3
  • shard2svr1, shard2svr2, shard2svr3
  • shard3svr1, shard3svr2, shard3svr3
• Router (mongos): router

Setup

• Cloud Server 1 docker-compose -f docker-compose1.yml -d

• Cloud Server 2 docker-compose -f docker-compose2.yml -d

• Cloud Server 3 docker-compose -f docker-compose3.yml -d

• Cloud Router (Application Cloud) docker-compose -f docker-router.yml -d

Configuration

• Config Server

docker exec -it cfgsvr1
mongo < /scripts/init-configserver.js

• Shard1

docker exec -it shard1svr1
mongo < /scripts/init-shard1.js

• Shard2

docker exec -it shard2svr1
mongo < /scripts/init-shard2.js

• Shard3

docker exec -it shard3svr1
mongo < /scripts/init-shard3.js

• Router

docker exec -it router
mongo < /scripts/init-router.js

Sharding a Mongo Collection

docker exec -it router
mongo

• Check status

router> sh.status()

Enable Sharding of Database

sh.enableSharding("dbName")

Shard Empty Collection Data

sh.shardCollection( "dbName.myCollections", {"field": 1, ...} )
sh.shardCollection( "dbName.myCollections", {"field": "hashed", ...} )

Ex:

sh.shardCollection( "dbName.users", { _id: "hashed" } )
sh.shardCollection( "dbName.invoices", { tranType: "hashed", tranDate: "hashed" } )

Shard Exist Collection Data

• Create Collection Index

db.myCollections.createIndex({"field": "hashed"})

• Sharding Collection

sh.shardCollection( "dbName.myCollections", {"field": "hashed"} )

Check Collection Sharding

db.myCollections.getShardDistribution()

References

• YouTube
• How to choose a shard key for MongoDB
• Choosing a Mongo Shard Key
• Shard keys