Kubernetes mongodb shard cluster

Mongo db shard cluster built on kubernetes. This configuration include:

3 node as config replica set
4 shard with 3 node as replica set for each shard
2 node as mongos router

Create cluster

./cluster-tear-up.sh

Deploy Mongo

In your master node do

./initiate.sh

initate.sh will deploy for you all pods and will create all needed services.

Connecting to mongo

For example to connect to your cluster:

ssh into a pod kubectl exec -it <POD-NAME> -- /bin/bash (you can get the pod name from kubectl get pods)
from the pod run mongo mongodb://mongos1:27017 to view the cluster status from a mongo shell do
run sh.status() and the output should be

mongos> sh.status()
--- Sharding Status ---
...
...
shards:
        {  "_id" : "rs1",  "host" : "rs1/mongosh1-1:27017,mongosh1-2:27017,mongosh1-3:27017",  "state" : 1 }
        {  "_id" : "rs2",  "host" : "rs2/mongosh2-1:27017,mongosh2-2:27017,mongosh2-3:27017",  "state" : 1 }
        {  "_id" : "rs3",  "host" : "rs3/mongosh3-1:27017,mongosh3-2:27017,mongosh3-3:27017",  "state" : 1 }
        {  "_id" : "rs4",  "host" : "rs4/mongosh4-1:27017,mongosh4-2:27017,mongosh4-3:27017",  "state" : 1 }
...

Clean

To remove all pods

./clean.sh

Deploy different number of shard replica set

Edit in config file SHARD_REPLICA_SET and set the desired number
Create for each additional replica set a file named mongo_sh_N.yaml
Copy content from mongo_sh_1.yaml
Replace all occurrences of mongosh1 with mongoshN
Replace all occurrences of rs1 with rsN

Delete Cluster

./cluster-tear-down

TODO

add PersistVolumes (see PersistentVolumes, PersistentVolumeClaims, Disk)

Resources

Using preexisiting Persistent Disks as PersistentVolumes - it shows how to create a persistent disk (together with persistent volumes, and persistent volume claims) and how a node can use a persistent volume
deployments_vs_statefulsets - confirmation that for stateful applications (e.g. a db) you need statefulsets and not deployments
Overall page about persistent volume
Repo already using mongo shards with persistent disk and volumes - The script does not work (probably outdated), however it can be used for a template on how to manage persistent disks, statefulsets, etc.

Aerius42/kubernetes-mongo-shard-cluster