Rocket Chat can be run on-premise, with a pretty lean set of requirements; the application just needs a MongoDB database to get up and running, and this is particularly quick if you make use of their Docker images for the app. I planned to run a pretty active instance for a community project I recently began working on, and decided Kubernetes would make a quick, elastic way to run the server, and this turned out to be an excellent use for the StatefulSet resource.
Creating a MongoDB replica set was pretty straightforward — the StatefulSet allows you to use consistent naming, among other things, which proves useful here for your Rocket Chat server Deployment which I’ll cover in a moment.
Create a Service first for rocketchat-mongo-service along with the StatefulSet:
--- kind: Service apiVersion: v1 metadata: name: rocketchat-mongo-service spec: selector: app: rocketchat-mongo ports: - protocol: TCP port: 27017 targetPort: 27017 --- apiVersion: apps/v1 kind: StatefulSet metadata: name: rocketchat-mongo spec: selector: matchLabels: app: rocketchat-mongo serviceName: "rocketchat-mongo" replicas: 3 template: metadata: labels: app: rocketchat-mongo spec: terminationGracePeriodSeconds: 10 containers: - name: mongodb image: mongo:3.2 ports: - containerPort: 27017 name: web command: ["mongod"] args: ["--replSet","rs0","--smallfiles","--oplogSize","128","--storageEngine=mmapv1"] volumeMounts: - name: mongo-persistent-storage mountPath: /data/db volumeClaimTemplates: - name: mongo-persistent-storage annotations: volume.beta.kubernetes.io/storage-class: "fast" spec: accessModes: ["ReadWriteOnce"] resources: requests: storage: 100Gi So, this creates a replicaSet and DNS entries for rocketchat-mongo-service-{0,1,2}.default and for your Deployment, you’ll want to make use of the connection string for the Replica Set:
mongodb://rocketchat-mongo-service-0.default,rocketchat-mongo-service-1.default,rocketchat-mongo-service-2.mongo:27017 and use this in your Deployment:
--- kind: Service apiVersion: v1 metadata: name: rocketchat-server-service spec: selector: app: rocketchat-server ports: - protocol: TCP port: 33000 targetPort: 3000 type: LoadBalancer --- apiVersion: apps/v1 kind: Deployment metadata: name: rocketchat-server-deployment labels: app: rocketchat-server spec: replicas: 1 selector: matchLabels: app: rocketchat-server template: metadata: labels: app: rocketchat-server spec: containers: - name: rocketchat-server image: rocketchat/rocket.chat:latest env: - name: PORT value: "3000" - name: ROOT_URL value: "[http://localhost:3000](http://localhost:3000)" - name: MONGO_URL value: "mongodb://rocketchat-mongo-service-0.default,rocketchat-mongo-service-1.default,rocketchat-mongo-service-2.mongo:27017/rocketchat" - name: MONGO_OPLOG_URL value: "mongodb://rocketchat-mongo-service-0.default,rocketchat-mongo-service-1.default,rocketchat-mongo-service-2.mongo:27017/local" ports: - containerPort: 3000 which consumes that replica set connection string for MONGO_URL and MONGO_OPLOG_URL .
Keep in mind that the Deployment will rely on the MongoDB StatefulSet, so run these in that order:
kubectl create -f rocketchat-mongodb.yaml and once the output from:
kubectl get pods -l app=rocketchat-mongo indicates 3/3 pods are Running , proceed to apply the rocketchat-server deployment, and once applied, you can access your Rocket Chat UI at http://$LB_ADDRESS:$SERVICE_PORT .
More about Rocket Chat’s Docker image can be found in their documentation for a Docker Compose-based deployment:
https://rocket.chat/docs/installation/docker-containers/docker-compose/
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