MongoDB statefulset for kubernetes with authentication and replication

mongo-statefulset.yaml

## Generate a key
# openssl rand -base64 741 > mongodb-keyfile
## Create k8s secrets
# kubectl create secret generic mongo-key --from-file=mongodb-keyfile
---
apiVersion: v1
kind: Service
metadata:
  name: mongo
  labels:
    name: mongo
spec:
  ports:
  - port: 27017
    targetPort: 27017
  clusterIP: None
  selector:
    role: mongo
---
apiVersion: apps/v1beta1
kind: StatefulSet
metadata:
  name: mongo
spec:
  serviceName: "mongo"
  replicas: 1
  template:
    metadata:
      labels:
        role: mongo
        environment: test
    spec:
      terminationGracePeriodSeconds: 10
      containers:
        - name: mongo
          image: mongo:3.4.9
          command:
          - /bin/sh
          - -c
          - >
            if [ -f /data/db/admin-user.lock ]; then
              mongod --replSet rs0 --clusterAuthMode keyFile --keyFile /etc/secrets-volume/mongodb-keyfile --setParameter authenticationMechanisms=SCRAM-SHA-1;
            else
              mongod --auth;
            fi;
          lifecycle:
            postStart:
              exec:
                command:
                - /bin/sh
                - -c
                - >
                  if [ ! -f /data/db/admin-user.lock ]; then
                    sleep 5;
                    touch /data/db/admin-user.lock
                    if [ "$HOSTNAME" = "mongo-0" ]; then
                      mongo --eval 'db = db.getSiblingDB("admin"); db.createUser({ user: "admin", pwd: "password", roles: [{ role: "root", db: "admin" }]});';
                    fi;
                    mongod --shutdown;
                  fi;
          ports:
            - containerPort: 27017
          volumeMounts:
            - name: mongo-key
              mountPath: "/etc/secrets-volume"
              readOnly: true
            - name: mongo-persistent-storage
              mountPath: /data/db
        - name: mongo-sidecar
          image: cvallance/mongo-k8s-sidecar
          env:
            - name: MONGO_SIDECAR_POD_LABELS
              value: "role=mongo,environment=test"
            - name: MONGODB_USERNAME
              value: admin
            - name: MONGODB_PASSWORD
              value: password
            - name: MONGODB_DATABASE
              value: admin
      volumes:
      - name: mongo-key
        secret:
          defaultMode: 0400
          secretName: mongo-key
  volumeClaimTemplates:
  - metadata:
      name: mongo-persistent-storage
      annotations:
        volume.beta.kubernetes.io/storage-class: "fast"
    spec:
      accessModes: [ "ReadWriteOnce" ]
      resources:
        requests:
          storage: 100Gi