How to create a backup cron job for MongoDB database on kubernetes (GKE)

backup-cron-job.yml

kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: cluster-admin
rules:
  - apiGroups: [""]
    resources: ["pods", "pods/log"]
    verbs: ["get", "list"]
  - apiGroups: [""]
    resources: ["pods/exec", "pods/cp"]
    verbs: ["create", "update", "patch"]

---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: cluster-admin
  namespace: default
subjects:
  - kind: ServiceAccount
    name: cluster-reader
    namespace: default
roleRef:
  kind: ClusterRole
  name: cluster-admin
  apiGroup: rbac.authorization.k8s.io

---
kind: ServiceAccount
apiVersion: v1
metadata:
  name: cluster-reader
  namespace: default

---
kind: ConfigMap
apiVersion: v1
metadata:
  name: backup-script
data:
  backup.sh: |
    #!/bin/bash
    JSON_FILE=$(cat <<-END
        {
            "type": "service_account",
            "project_id": "your-project",
            "private_key_id": "${GCS_PRIVATE_KEY_ID}",
            "private_key": "${GCS_PRIVATE_KEY}",
            "client_email": "storage-update@your-project.iam.gserviceaccount.com",
            "client_id": "${GCS_CLIENT_ID}",
            "auth_uri": "https://accounts.google.com/o/oauth2/auth",
            "token_uri": "https://oauth2.googleapis.com/token",
            "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
            "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/storage-update%40your-project.iam.gserviceaccount.com"
        }
    END
    )

    echo "$JSON_FILE" > key.json
    gcloud auth activate-service-account --key-file=key.json
    mkdir backups
    BACKUP_DIR=$(date +'%m.%d.%Y')
    array=($(kubectl get pods | grep mongo | awk '{ print $1 }'))
    for KEY in "${!array[@]}"; do
      kubectl exec -i ${array[$KEY]} -- bash -c "cd tmp && mongodump --archive > mongo.dump && exit"
      kubectl cp ${array[$KEY]}:/tmp/mongo.dump /backups/${array[$KEY]}.dump
    done
    gsutil cp -r /backups gs://your-backups/${BACKUP_DIR}

---
apiVersion: batch/v1beta1
kind: CronJob
metadata:
  name: cron-backup
spec:
  schedule: "0 0 * * *"
  jobTemplate:
    spec:
      template:
        spec:
          serviceAccountName: cluster-reader
          restartPolicy: OnFailure
          volumes:
            - name: backup-script
              configMap:
                name: backup-script
                defaultMode: 0777
          containers:
            - name: runner
              image: gcr.io/google.com/cloudsdktool/cloud-sdk:latest
              command: ["/bin/bash", "-c", "/scripts/backup.sh"]
              securityContext:
                runAsUser: 0
              volumeMounts:
                - name: backup-script
                  mountPath: /scripts/backup.sh
                  subPath: backup.sh
              env:
                - name: GOOGLE_STORAGE_BUCKET
                  value: your-project-backup
                - name: GCS_PRIVATE_KEY_ID
                  valueFrom:
                    secretKeyRef:
                      name: gcs-private-key-id
                      key: GCS_PRIVATE_KEY_ID
                - name: GCS_CLIENT_ID
                  valueFrom:
                    secretKeyRef:
                      name: gcs-client-id
                      key: GCS_CLIENT_ID
                - name: GCS_PRIVATE_KEY
                  valueFrom:
                    secretKeyRef:
                      name: gcs-private-key
                      key: GCS_PRIVATE_KEY