Kubernetes mongo Installation

Ok this time we will discuss about installation mongo DB on kubernetes. 2 main things that is very important in installing database on kubernetes / k8s are persistence volume and statefulset. StatefulSet maintains a sticky identity for each of their Pods, so that when the pod is broken or deleted, it is like will restart / create new pod with same pod name as before.

persistence volume is needed to store the database date. persistence volume is a directory that mounted to pod and the directory is persistent even though the pod is deleted. The idea is storage for database must be persistence so that what ever happened to database application we still able to backup the database data.

step to deploy mongo db on kubernetes :

1. persistence volume

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mongodb-sit-claim
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 40G

2. Create mongo deployment

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: sit-ml-mongo
spec:
  replicas: 1
  selector:
    matchLabels:
      app: sit-ml-mongo
  serviceName: sit-ml-mongo
  template:
    metadata:
      labels:
        app: sit-ml-mongo
    spec:
      nodeSelector:
        purpose: ml_database
        environment: ml_sit
      volumes:
      - name: data
        persistentVolumeClaim:
          claimName: mongodb-sit-claim
      containers:
      - command:
        - numactl
        - --interleave=all
        - mongod
        - --bind_ip
        - 0.0.0.0
        - --auth
        - --setParameter
        - authenticationMechanisms=SCRAM-SHA-1
        - --wiredTigerCacheSizeGB
        - "0.25"
        image: mongo:4.4
        imagePullPolicy: IfNotPresent
        name: mongo
        ports:
        - containerPort: 27017
          protocol: TCP
        resources:
          limits:
            cpu: "2"
            memory: 7G
          requests:
            cpu: "0.5"
            memory: 2G
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
        volumeMounts:
        - mountPath: /data/db
          name: data
      restartPolicy: Always

example of result :

base on picture above, we have /data/db where database data is stored. the folder /data/db comes from

volumeMounts:
        - mountPath: /data/db
          name: data