Introduction
============

**CloudNativePG** is an open source `operator <https://kubernetes.io/docs/concepts/extend-kubernetes/operator/>`_ 

designed to manage `PostgreSQL <https://www.postgresql.org/>`_  workloads on any supported
 `Kubernetes <https://kubernetes.io>`_  cluster running in private, public, hybrid, or multi-cloud
environments. CloudNativePG adheres to DevOps principles and concepts
such as declarative configuration and immutable infrastructure.

It defines a new Kubernetes resource called ``Cluster`` representing a
PostgreSQL cluster made up of a single primary and an optional number of
replicas that co-exist in a chosen Kubernetes namespace for High
Availability and offloading of read-only queries.

Applications that reside in the same Kubernetes cluster can access the
PostgreSQL database using a service which is solely managed by the
operator, without having to worry about changes of the primary role
following a failover or a switchover. Applications that reside outside
the Kubernetes cluster, need to configure a Service or Ingress object to
expose the Postgres via TCP. Web applications can take advantage of the
native connection pooler based on PgBouncer.

CloudNativePG was originally built by `EDB <https://www.enterprisedb.com>`_  , then released open
source under Apache License 2.0 and submitted for CNCF Sandbox in April
2022. The `source code repository is in Github <https://github.com/cloudnative-pg/cloudnative-pg>`_  .

..  Note::
   Based on the  :ref:`Operator Capability Levels model <Operator Capability Levels>`  , users can expect a **"Level V - Auto Pilot"** set of capabilities from the CloudNativePG Operator.

Supported Kubernetes distributions
----------------------------------

Each minor release of CloudNativePG is designed to work with a range of
Kubernetes versions, usually the ones supported by the CNCF at the time
the minor version was first released.

Please refer to the :ref:`Supported releases <Supported releases>`  page for details.

Container images
----------------

The `CloudNativePG community <https://github.com/cloudnative-pg>`_  maintains container images for both the operator and
the operand, that is PostgreSQL.

The CloudNativePG operator container images are `distroless <https://github.com/GoogleContainerTools/distroless>`_ 

and available on the `cloudnative-pg <https://github.com/cloudnative-pg/cloudnative-pg/pkgs/container/cloudnative-pg>`_  .

The PostgreSQL operand container images are available for all the
 `PGDG supported versions of PostgreSQL <https://www.postgresql.org/>`_  , on multiple architectures, directly from the
 `postgres-containers <https://github.com/cloudnative-pg/postgres-containers/pkgs/container/postgresql>`_  .

Additionally, the Community provides images for the :ref:`PostGIS extension <PostGIS>`  .

..  Warning::
   CloudNativePG requires that all nodes in a Kubernetes cluster have the same CPU architecture, thus a hybrid CPU architecture Kubernetes cluster is not supported.

Main features
-------------

-  Direct integration with Kubernetes API server for High Availability,
   without requiring an external tool

-  Self-Healing capability, through: \* failover of the primary instance
   by promoting the most aligned replica \* automated recreation of a
   replica

-  Planned switchover of the primary instance by promoting a selected
   replica

-  Scale up/down capabilities

-  Definition of an arbitrary number of instances (minimum 1 - one
   primary server)

-  Definition of the *read-write* service, to connect your applications
   to the only primary server of the cluster

-  Definition of the *read-only* service, to connect your applications
   to any of the instances for reading workloads

-  Declarative management of PostgreSQL configuration, including certain
   popular Postgres extensions through the cluster ``spec`` :
   ``pgaudit`` , ``auto_explain`` , ``pg_stat_statements`` , and
   ``pg_failover_slots``

-  Declarative management of Postgres roles, users and groups

-  Support for Local Persistent Volumes with PVC templates

-  Reuse of Persistent Volumes storage in Pods

-  Separate volume for WAL files

-  Rolling updates for PostgreSQL minor versions

-  In-place or rolling updates for operator upgrades

-  TLS connections and client certificate authentication

-  Support for custom TLS certificates (including integration with
   cert-manager)

-  Continuous WAL archiving to an object store (AWS S3 and
   S3-compatible, Azure Blob Storage, and Google Cloud Storage)

-  Backups on volume snapshots (where supported by the underlying
   storage classes)

-  Backups on object stores (AWS S3 and S3-compatible, Azure Blob
   Storage, and Google Cloud Storage)

-  Full recovery and Point-In-Time recovery from an existing backup on
   volume snapshots or object stores

-  Offline import of existing PostgreSQL databases, including major
   upgrades of PostgreSQL

-  Fencing of an entire PostgreSQL cluster, or a subset of the instances
   in a declarative way

-  Hibernation of a PostgreSQL cluster in a declarative way

-  Support for Synchronous Replicas

-  Support for HA physical replication slots at cluster level

-  Backup from a standby

-  Backup retention policies (based on recovery window, only on object
   stores)

-  Parallel WAL archiving and restore to allow the database to keep up
   with WAL generation on high write systems

-  Support tagging backup files uploaded to an object store to enable
   optional retention management at the object store layer Replica
   clusters for

-  PostgreSQL deployments across multiple Kubernete clusters, enabling
   private, public, hybrid, and multi-cloud architectures

-  Connection pooling with PgBouncer

-  Support for node affinity via ``nodeSelector``

-  Native customizable exporter of user defined metrics for Prometheus
   through the ``metrics`` port (9187)

-  Standard output logging of PostgreSQL error messages in JSON format

-  Automatically set ``readOnlyRootFilesystem`` security context for
   pods

-  ``cnpg`` plugin for ``kubectl``

-  Simple bind and search+bind LDAP client authentication

-  Multi-arch format container images

-  OLM installation

..  Note::
   CloudNativePG does not use `StatefulSet` s for managing data persistence. Rather, it manages persistent volume claims (PVCs) directly. If you are curious, read  :ref:`Custom Pod Controller <Custom Pod Controller>`  to know more.

About this guide
----------------

Follow the instructions in the :ref:`Quickstart <Quickstart>`  to test CloudNativePG on a
local Kubernetes cluster using Kind, or Minikube.

In case you are not familiar with some basic terminology on Kubernetes
and PostgreSQL, please consult the :ref:`Before You Start <Before You Start>`  .

-  `Postgres, PostgreSQL and the Slonik Logo <https://www.postgresql.org/about/policies/trademarks/>`_ 

are trademarks or registered trademarks of the PostgreSQL Community
Association of Canada, and used with their permission.\*