Postgres Cluster

Using Zalando Postgres Operator in Kubernetes

This guide provides instructions for end users on how to deploy a PostgreSQL cluster using the Zalando Postgres Operator in a Kubernetes environment.

1. Deploying a PostgreSQL Cluster

You can deploy your PostgreSQL cluster by creating a Postgresql custom resource (CR).

Example: postgres-cluster.yaml

apiVersion: "acid.zalan.do/v1"
kind: "postgresql"
metadata:
  name: "my-postgres-cluster"
spec:
  teamId: "my-team"
  volume:
    size: 10Gi
  numberOfInstances: 3
  users:
    myapp:  # database users
      - superuser
      - createdb
  databases:
    mydatabase: myapp  # database name: owner
  postgresql:
    version: "14"  # Postgres version
  resources:
    requests:
      cpu: "500m"
      memory: "500Mi"
    limits:
      cpu: "1"
      memory: "1Gi"

Apply the Cluster Manifest:

kubectl apply -n default -f postgres-cluster.yaml

Replace “default” here and later with your actual namespace.

This command will create a PostgreSQL cluster with the following configuration:

• 3 instances of PostgreSQL
• A database named mydatabase owned by myapp user
• 10Gi of storage per instance
• Resource requests and limits configured for each instance
• PostgreSQL version 14

2. Accessing the PostgreSQL Cluster

Once the cluster is running, you can connect to PostgreSQL using a Kubernetes service that is automatically created by the operator. The service will follow this format:

• Cluster Service: my-postgres-cluster (default name)
• Primary Endpoint: my-postgres-cluster.default.svc.cluster.local
• Replica Endpoints: my-postgres-cluster-repl.default.svc.cluster.local

Get password for user postgres:

kubectl get secret postgres.my-postgres-cluster.credentials.postgresql.acid.zalan.do -o 'jsonpath={.data.password}' | base64 -d

You can connect to the primary endpoint like this:

kubectl run -i --tty --rm debug --image=postgres -- bash
psql -h my-postgres-cluster -U postgres

The user for your created database (mydatabase) will have a different password stored in myapp.my-postgres-cluster.credentials.postgresql.acid.zalan.do.

3. Scaling the PostgreSQL Cluster

To scale the cluster, you can modify the numberOfInstances field in your postgres-cluster.yaml file. For example, to scale to 5 instances:

numberOfInstances: 5

Apply the changes:

kubectl apply -f postgres-cluster.yaml

The operator will handle scaling up or down the number of PostgreSQL instances automatically.

4. Monitoring the Cluster

The Zalando Postgres Operator provides built-in support for monitoring the health and performance of the PostgreSQL cluster. You can check the status of your cluster by running:

kubectl get postgresql

You should see output like:

NAME                TEAM   VERSION   STATUS    INSTANCES   AGE
my-postgres-cluster my-team 14       Running   3           5m

4. Choosing the storage for the cluster

Linstor storageClass is preferred as it provides the best performance for postgres. Refer to linstor storage docs. Example of adding the linstor storage:

spec:
  nodeAffinity:
    requiredDuringSchedulingIgnoredDuringExecution:
      nodeSelectorTerms:
      - matchExpressions:
        - key: nautilus.io/linstor
          operator: In
          values:
          - "true"
volume:
    size: 10Gi
    storageClass: linstor-igrok

This is how you can manage and deploy a PostgreSQL cluster using the Zalando Postgres Operator in Kubernetes. For more advanced configurations, refer to the full documentation of the operator.