# Zalando Postgres Operator — Production PostgreSQL Clusters on Kubernetes

> A Kubernetes operator that manages the full lifecycle of PostgreSQL clusters with patroni-based HA, connection pooling, and automated backups.

## Install

Save as a script file and run:

# Zalando Postgres Operator — Production PostgreSQL Clusters on Kubernetes

## Quick Use
```bash
# Install the operator
kubectl apply -k github.com/zalando/postgres-operator/manifests
# Create a PostgreSQL cluster
cat <<EOF | kubectl apply -f -
apiVersion: acid.zalan.do/v1
kind: postgresql
metadata:
  name: my-cluster
spec:
  teamId: "myteam"
  numberOfInstances: 3
  postgresql:
    version: "16"
  volume:
    size: 10Gi
EOF
```

## Introduction
The Zalando Postgres Operator manages PostgreSQL clusters on Kubernetes as a custom resource. Developed and battle-tested at Zalando for running hundreds of PostgreSQL instances in production, it handles cluster creation, high availability via Patroni, connection pooling, rolling upgrades, and automated WAL-based backups.

## What Zalando Postgres Operator Does
- Creates and manages multi-replica PostgreSQL clusters as Kubernetes custom resources
- Provides automatic failover and high availability using Patroni consensus
- Configures PgBouncer connection pooling sidecars automatically
- Handles rolling minor and major version upgrades with minimal downtime
- Manages continuous WAL archiving and base backups to S3-compatible storage

## Architecture Overview
The operator watches for postgresql custom resources and reconciles the desired state. Each cluster runs as a StatefulSet with Patroni managing leader election via Kubernetes endpoints or etcd. A sidecar PgBouncer handles connection pooling. The operator creates services for the primary and replica endpoints, manages secrets for database credentials, and configures logical backup CronJobs. WAL-E or WAL-G handles continuous backup to object storage.

## Self-Hosting & Configuration
- Deploy the operator via kubectl, Helm chart, or Kustomize manifests
- Configure S3/GCS/Azure Blob credentials for WAL archiving and base backups
- Set global defaults in the OperatorConfiguration CRD (instance sizes, storage classes, backup schedules)
- Define per-cluster settings (replicas, resources, PostgreSQL parameters) in the postgresql CR
- Enable the operator UI for a web-based view of all managed clusters

## Key Features
- Patroni-based HA with automatic leader election and replica promotion
- Built-in PgBouncer connection pooling with transparent reconfiguration on failover
- Logical and physical backup strategies with point-in-time recovery
- Clone-from-backup: spin up new clusters from existing WAL archives
- Team-based access control: maps Kubernetes teams to database roles automatically

## Comparison with Similar Tools
- **CloudNativePG** — newer operator with declarative backup management; Zalando operator is more mature with Patroni-based HA
- **CrunchyData PGO** — comprehensive operator with pgBackRest; Zalando operator uses WAL-G and has simpler CRD semantics
- **KubeDB** — multi-database operator; Zalando operator is PostgreSQL-specialized
- **Bitnami PostgreSQL Helm chart** — simple StatefulSet deployment without operator-level lifecycle management

## FAQ
**Q: How does failover work?**
A: Patroni runs inside each PostgreSQL pod and uses Kubernetes endpoints for leader election. When the primary fails, Patroni promotes the most up-to-date replica within seconds.

**Q: Can I use it with existing PostgreSQL databases?**
A: You can clone from an existing WAL archive or logical backup, but direct import of a running external database requires manual migration steps.

**Q: What PostgreSQL versions are supported?**
A: The operator supports PostgreSQL 12 through 17. The version is specified in the cluster CR and can be upgraded via rolling update.

**Q: Does it support connection pooling?**
A: Yes. The operator can deploy PgBouncer as a sidecar or separate deployment, configured automatically based on the cluster spec.

## Sources
- https://github.com/zalando/postgres-operator
- https://postgres-operator.readthedocs.io

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Source: https://tokrepo.com/en/workflows/asset-5faf8a37
Author: Script Depot