Database operators example in Kubernetes - Commands & Configuration

Introduction

Managing databases in Kubernetes can be complex because databases need special care for storage and backups. Database operators help automate these tasks so your database runs smoothly without manual work.

When you want to run a PostgreSQL database inside Kubernetes with automatic backups and scaling.

When you need to manage a MySQL database that recovers automatically after failures.

When you want to deploy a MongoDB cluster with easy updates and monitoring inside Kubernetes.

When you want to avoid manual setup of persistent storage and configuration for your database.

When you want your database to be managed like any other Kubernetes resource with simple commands.

Config File - postgres-operator.yaml

postgres-operator.yaml

apiVersion: postgres-operator.crunchydata.com/v1beta1
kind: PostgresCluster
metadata:
  name: my-postgres
  namespace: default
spec:
  instances:
    - name: instance1
      replicas: 1
  backups:
    pgbackrest:
      repos:
        - name: repo1
          volume:
            volumeClaimSpec:
              accessModes:
                - ReadWriteOnce
              resources:
                requests:
                  storage: 1Gi
  storage:
    volumes:
      - name: data
        volumeClaimSpec:
          accessModes:
            - ReadWriteOnce
          resources:
            requests:
              storage: 1Gi

This YAML file defines a PostgreSQL cluster managed by the Crunchy Data Postgres Operator.

apiVersion and kind specify the operator resource type.

metadata names the cluster.

spec.instances defines one instance with one replica.

spec.backups configures backup storage using pgBackRest.

spec.storage sets persistent storage for the database data.

Commands

This command creates the PostgreSQL cluster resource in Kubernetes using the operator. It tells Kubernetes to start managing the database with the settings in the YAML file.

Terminal

kubectl apply -f postgres-operator.yaml

Expected Output

postgrescluster.postgres-operator.crunchydata.com/my-postgres created

This command lists the pods created by the operator for the PostgreSQL cluster to check if the database is running.

Terminal

kubectl get pods -l postgres-operator.crunchydata.com/cluster=my-postgres

Expected Output

NAME                                READY   STATUS    RESTARTS   AGE

my-postgres-instance1-0              1/1     Running   0          30s

→

-l - Filter pods by label to show only those belonging to the PostgreSQL cluster

This command shows detailed information about the PostgreSQL cluster resource, including status, events, and conditions managed by the operator.

Terminal

kubectl describe postgrescluster my-postgres

Expected Output

Name:         my-postgres

Namespace:    default

Labels:       

Annotations:  

API Version:  postgres-operator.crunchydata.com/v1beta1

Kind:         PostgresCluster

Spec:

  Instances:

    Name:      instance1

    Replicas:  1

  Storage:

    Volumes:

      Name: data

      Storage Request: 1Gi

Status:

  State: Running

Events:

  Type    Reason             Age   From                       Message

  ----    ------             ----  ----                       -------

  Normal  SuccessfulCreate   1m    postgres-operator-controller  Created pod my-postgres-instance1-0

Key Concept

If you remember nothing else from this pattern, remember: database operators automate complex database tasks inside Kubernetes so you can manage databases like regular apps.

Common Mistakes

Applying the operator resource without installing the database operator first

Kubernetes does not recognize the custom resource and returns an error because the operator controller is missing.

Install the database operator in the cluster before applying any database custom resources.

Not specifying persistent storage in the YAML file

The database pods will not have storage to save data, causing data loss on pod restarts.

Always define persistent volume claims in the storage section to keep data safe.

Summary

Create a database cluster resource YAML file for the operator to manage.

Apply the YAML file with kubectl to start the database cluster.

Check pods with kubectl get pods to verify the database is running.

Use kubectl describe on the cluster resource to see detailed status and events.