Image Overview: postgres-operator

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Creates and manages PostgreSQL clusters running in Kubernetes.

Download this Image

The image is available on cgr.dev:

docker pull cgr.dev/chainguard/postgres-operator:latest

Usage

The operator can be installed by using the provided Helm chart which saves you the manual steps. The charts for both the Postgres Operator and its UI are hosted via the gh-pages branch. They only work only with Helm v3. Helm v2 support was dropped with v1.8.0.

# add repo for postgres-operator
helm repo add postgres-operator-charts https://opensource.zalando.com/postgres-operator/charts/postgres-operator

# install the postgres-operator
helm install postgres-operator postgres-operator-charts/postgres-operator  \
 --set image.registry=cgr.dev \
 --set image.repository=chainguard/postgres-operator \
 --set image.tag=latest

Check if Postgres Operator is running

Starting the operator may take a few seconds. Check if the operator pod is running before applying a Postgres cluster manifest.

# if you've created the operator using yaml manifests
kubectl get pod -l name=postgres-operator

# if you've created the operator using helm chart
kubectl get pod -l app.kubernetes.io/name=postgres-operator

If the operator doesn’t get into Running state, either check the latest K8s events of the deployment or pod with kubectl describe or inspect the operator logs:

kubectl logs "$(kubectl get pod -l name=postgres-operator --output='name')"

Create a Postgres cluster

If the operator pod is running it listens to new events regarding postgresql resources. Now, it’s time to submit your first Postgres cluster manifest.

# create a Postgres cluster
cat <<EOF > "${TMPDIR}/minimal-postgres-manifest.yaml"
apiVersion: "acid.zalan.do/v1"
kind: postgresql
metadata:
  name: acid-minimal-cluster
spec:
  teamId: "acid"
  volume:
    size: 1Gi
  numberOfInstances: 2
  users:
    zalando:  # database owner
    - superuser
    - createdb
    foo_user: []  # role for application foo
  databases:
    foo: zalando  # dbname: owner
  preparedDatabases:
    bar: {}
  postgresql:
    version: "16"
EOF

kubectl create -f "${TMPDIR}/minimal-postgres-manifest.yaml" 

After the cluster manifest is submitted and passed the validation the operator will create Service and Endpoint resources and a StatefulSet which spins up new Pod(s) given the number of instances specified in the manifest. All resources are named like the cluster. The database pods can be identified by their number suffix, starting from -0. They run the Spilo container image by Zalando. As for the services and endpoints, there will be one for the master pod and another one for all the replicas (-repl suffix). Check if all components are coming up. Use the label application=spilo to filter and list the label spilo-role to see who is currently the master.

# check the deployed cluster
kubectl get postgresql

# check created database pods
kubectl get pods -l application=spilo -L spilo-role

# check created service resources
kubectl get svc -l application=spilo -L spilo-role

Connect to the Postgres cluster via psql

# get name of master pod of acid-minimal-cluster
export PGMASTER=$(kubectl get pods -o jsonpath={.items..metadata.name} -l application=spilo,cluster-name=acid-minimal-cluster,spilo-role=master -n default)

# set up port forward
kubectl port-forward $PGMASTER 6432:5432 -n default

Open another CLI and connect to the database using e.g. the psql client. When connecting with a manifest role like foo_user user, read its password from the K8s secret which was generated when creating acid-minimal-cluster. As non-encrypted connections are rejected by default set SSL mode to require:

export PGPASSWORD=$(kubectl get secret postgres.acid-minimal-cluster.credentials.postgresql.acid.zalan.do -o 'jsonpath={.data.password}' | base64 -d)
export PGSSLMODE=require
psql -U postgres -h localhost -p 6432