How to deploy MongoDB K8s

This is a guide on how to deploy Charmed MongoDB K8s as a replica set or a sharded cluster.

Summary

• Create a MongoDB replica set
  • Deploy a single replica
  • Deploy multiple replicas
• Create a MongoDB sharded cluster
  • Deploy cluster components with a single replica
  • Deploy cluster components with multiple replicas
  • Integrate cluster components

Create a MongoDB replica set

You can create one or multiple replicas at once when deploying MongoDB K8s.

Deploy a single replica

To deploy a single unit of MongoDB as a replica set, run:

juju deploy mongodb-k8s --trust

The --trust flag is necessary to grant the application access to the Kubernetes cluster.

Deploy multiple replicas

To deploy MongoDB with multiple replicas, specify the number of desired replicas with the -n option:

juju deploy mongodb-k8s -n <number_of_replicas>

Create a MongoDB sharded cluster

To create a sharded cluster, we must first deploy each cluster component separately with a manually defined role, then integrate them.

Deploy cluster components with a single replica

Deploying a shard application will assign it one replica by default.

To deploy a sharded cluster with two shards, run:

juju deploy mongodb-k8s --config role="config-server" <config_server_name>
juju deploy mongodb-k8s --config role="shard" <shard_name_0>
juju deploy mongodb-k8s --config role="shard" <shard_name_1>

This will deploy the latest stable release . To specify a different version, use the --channel flag, e.g. --channel=6/beta.

Deploy cluster components with multiple replicas

To configure the amount of replicas for a shard or config-server during deployment, just use the -n flag.

To deploy a shard and config-server with 3 replicas each, run:

juju deploy mongodb-k8s --config role="shard" <shard_name> -n 3
juju deploy mongodb-k8s --config role="config-server" <config_server_name> -n 3

This will deploy the latest stable release . To specify a different version, use the --channel flag, e.g. --channel=6/beta.

Note that you can also change the number of replicas for a shard or config server after deployment. See Scale replicas and shards > How to add shards to a cluster.

Integrate cluster components

To create a cluster, integrate the shard applications with the config-server application.

For the case of two shards and one config server, you would run:

juju integrate config-server:config-server <shard_name_0>:sharding
juju integrate config-server:config-server <shard_name_1>:sharding