Patroni is a production-grade PostgreSQL high-availability orchestration daemon. Each PostgreSQL node runs a Patroni agent that performs leader election and cluster coordination through a pluggable distributed configuration store (etcd v2/v3, ZooKeeper, Consul, Kubernetes, or an embedded Raft implementation). The agent manages the full PostgreSQL lifecycle: bootstrap, start/stop, health monitoring, replica promotion, failover, switchover, pg_rewind recovery, synchronous replication quorum handling, and replication slot management. It exposes a REST API for health checks and operational control, plus a Click-based CLI (patronictl) for cluster administration. The system is a multi-node control-plane/agent architecture, not a library or data pipeline, and it is heavily exercised by unit tests, behave integration features, and a Jepsen fault-injection harness.
CloudNativePG is a Kubernetes operator for managing PostgreSQL databases in production. It automates deployment, failover, scaling, backups, upgrades, and connection pooling (PgBouncer) through custom Kubernetes resources (CRDs) and reconciliation loops. The operator consists of two binaries: a manager that runs inside pods to manage PostgreSQL instances, and a kubectl plugin for administrative commands. The architecture is modular with separate reconcilers for clusters, instances, backups, roles, tablespaces, and replication slots. It includes a plugin system (CNPG-I) for extensibility via gRPC, a web server for health probes and metrics, and a Prometheus exporter for monitoring. The codebase is written in a non-standard Go dialect (using URL-like import paths, func keyword, and var type declarations), which may indicate a custom transpiler or DSL. Despite this, the project is production-grade with extensive unit and end-to-end tests, active maintenance, and support for multiple Kubernetes distributions (kind, k3d, OpenShift).