Day13 as #100DaysofMongoDB as #100daysofcode
Taking the Replication on kubernetes environment ahead, let us learn about how to do sharding in a kubernetes Environment.
A MongoDB sharded cluster consists of:
- shards: A replica set where each shard contains a subset of sharded cluster.
- mongos: Which acts as a query router
- config servers: Which store the meta data and configurations settings.
Here, we will be using docker containers to design a sharded structure with one sharded cluster, which is basically a replica set, one config server and one mongos.
Hence, 7 docker containers will be needed.
All the members of shard and config map and mongos will be running on different ports.
Deploying a sharded replica set using docker containers.
The docker compose file will look like:
version: '3'
services:
shard1svr1:
container_name: shard1svr1
image: mongo
command: mongod --shardsvr --replSet shard1rs --port 27017 --dbpath /data/db
ports:
- 50001:27017
volumes:
- shard1svr1:/data/db
shard1svr2:
container_name: shard1svr2
image: mongo
command: mongod --shardsvr --replSet shard1rs --port 27017 --dbpath /data/db
ports:
- 50002:27017
volumes:
- shard1svr2:/data/db
shard1svr3:
container_name: shard1svr3
image: mongo
command: mongod --shardsvr --replSet shard1rs --port 27017 --dbpath /data/db
ports:
- 50003:27017
volumes:
- shard1svr3:/data/db
volumes:
shard1svr1: {}
shard1svr2: {}
shard1svr3: {}
The command here, mongod --shardsvr means the mongod is started as sharded cluster.
The config server compose file would look similar with the command as
mongod --configsvr --replSet cfgrs --port 27017 --dbpath /data/db.
defining the mongod as config server.
Lastly the yaml file for mongos
version: '3'
services:
mongos:
container_name: mongos
image: mongo
command: mongos --configdb cfgrs/192.168.29.4:40001,192.168.29.4:40002,192.168.29.4:40003 --bind_ip 0.0.0.0 --port 27017
ports:
- 60000:27017
After all the docker compose have been created do
docker-compose -f configserver.yaml up -d
docker-compose -f shardserver.yaml up -d
docker-compose -f mongod.yaml up -d
The containers will look like:
aasawari.sahasrabuddhe@M-C02DV42LML85 sharding % docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
a89092ce4415 mongo "docker-entrypoint.s…" 12 minutes ago Up 12 minutes 0.0.0.0:60000->27017/tcp mongos
fea4644bc0e0 mongo "docker-entrypoint.s…" 15 minutes ago Up 14 minutes 0.0.0.0:50001->27017/tcp shard1svr1
da83eb637ae4 mongo "docker-entrypoint.s…" 15 minutes ago Up 14 minutes 0.0.0.0:50003->27017/tcp shard1svr3
4c7f0f0ecf86 mongo "docker-entrypoint.s…" 15 minutes ago Up 14 minutes 0.0.0.0:50002->27017/tcp shard1svr2
39418f832da9 mongo "docker-entrypoint.s…" 32 minutes ago Up 31 minutes 0.0.0.0:40003->27017/tcp cfgsvr3
9297b1bc78ab mongo "docker-entrypoint.s…" 32 minutes ago Up 31 minutes 0.0.0.0:40001->27017/tcp cfgsvr1
b1804155e587 mongo "docker-entrypoint.s…" 32 minutes ago Up 31 minutes 0.0.0.0:40002->27017/tcp cfgsvr2
08bcb43c7ff8 gcr.io/k8s-minikube/kicbase:v0.0.30 "/usr/local/bin/entr…" 9 days ago Up 7 hours 127.0.0.1:50295->22/tcp, 127.0.0.1:50296->2376/tcp, 127.0.0.1:50298->5000/tcp, 127.0.0.1:50299->8443/tcp, 127.0.0.1:50297->32443/tcp minikube
aasawari.sahasrabuddhe@M-C02DV42LML85 sharding %
After replica sets have been initiated in config server and sharded server with the respective port numbers as
mongo mongodb://192.168.29.4:40001 where 192.168.29.4 is the system IP address
Login to the mongos to add the shards to the mongos.
as
mongos> sh.addShard("shard1rs/192.168.29.4:50001,192.168.29.4:50002,192.168.29.4:50003")
mongos> sh.status()
--- Sharding Status ---
sharding version: {
"_id" : 1,
"minCompatibleVersion" : 5,
"currentVersion" : 6,
"clusterId" : ObjectId("623c84a6a12cb9bd172d459a")
}
shards:
{ "_id" : "shard1rs", "host" : "shard1rs/192.168.29.4:50001,192.168.29.4:50002,192.168.29.4:50003", "state" : 1, "topologyTime" : Timestamp(1648133766, 1) }
active mongoses:
"5.0.6" : 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:
No recent migrations
databases:
{ "_id" : "config", "primary" : "config", "partitioned" : true }
config.system.sessions
shard key: { "_id" : 1 }
unique: false
balancing: true
chunks:
shard1rs 1024
Further let us understand how to add data and access the data through these sharded clusters.
If you have any questions related to docker containers or deploying replica sets using docker containers, feel free to reach out.
Thanks
Aasawari
Share on twitter: https://twitter.com/Aasawari_24