Installation and upgrades

Installation on Kubernetes

Directly using the operator manifest

The operator can be installed like any other resource in Kubernetes, through a YAML manifest applied via kubectl.

You can install the latest operator manifest for this minor release as follows:

kubectl apply --server-side -f \
  https://raw.githubusercontent.com/cloudnative-pg/cloudnative-pg/main/releases/cnpg-1.24.0-rc1.yaml

You can verify that with:

kubectl get deployment -n cnpg-system cnpg-controller-manager

Using the cnpg plugin for kubectl

You can use the cnpg plugin to override the default configuration options that are in the static manifests.

For example, to generate the default latest manifest but change the watch namespaces to only be a specific namespace, you could run:

kubectl cnpg install generate \
  --watch-namespace "specific-namespace" \
  > cnpg_for_specific_namespace.yaml

Please refer to "cnpg plugin" documentation for a more comprehensive example.

Testing the latest development snapshot

If you want to test or evaluate the latest development snapshot of CloudNativePG before the next official patch release, you can download the manifests from the cloudnative-pg/artifacts which provides easy access to the current trunk (main) as well as to each supported release.

For example, you can install the latest snapshot of the operator with:

curl -sSfL \
  https://raw.githubusercontent.com/cloudnative-pg/artifacts/main/manifests/operator-manifest.yaml | \
  kubectl apply --server-side -f -

If you are instead looking for the latest snapshot of the operator for this specific minor release, you can just run:

curl -sSfL \
  https://raw.githubusercontent.com/cloudnative-pg/artifacts/main/manifests/operator-manifest.yaml | \
  kubectl apply --server-side -f -

Using the Helm Chart

The operator can be installed using the provided Helm chart.

Using OLM

CloudNativePG can also be installed using the Operator Lifecycle Manager (OLM) directly from OperatorHub.io.

Details about the deployment

In Kubernetes, the operator is by default installed in the cnpg-system namespace as a Kubernetes Deployment. The name of this deployment depends on the installation method. When installed through the manifest or the cnpg plugin, it is called cnpg-controller-manager by default. When installed via Helm, the default name is cnpg-cloudnative-pg.

You can get more information using the describe command in kubectl:

$ kubectl get deployments -n cnpg-system
NAME                READY   UP-TO-DATE   AVAILABLE   AGE
<deployment-name>   1/1     1            1           18m

kubectl describe deploy \
  -n cnpg-system \
  <deployment-name>

As with any Deployment, it sits on top of a ReplicaSet and supports rolling upgrades. The default configuration of the CloudNativePG operator comes with a Deployment of a single replica, which is suitable for most installations. In case the node where the pod is running is not reachable anymore, the pod will be rescheduled on another node.

If you require high availability at the operator level, it is possible to specify multiple replicas in the Deployment configuration - given that the operator supports leader election. Also, you can take advantage of taints and tolerations to make sure that the operator does not run on the same nodes where the actual PostgreSQL clusters are running (this might even include the control plane for self-managed Kubernetes installations).

Upgrades

Upgrading CloudNativePG operator is a two-step process:

1. upgrade the controller and the related Kubernetes resources
2. upgrade the instance manager running in every PostgreSQL pod

Unless differently stated in the release notes, the first step is normally done by applying the manifest of the newer version for plain Kubernetes installations, or using the native package manager of the used distribution (please follow the instructions in the above sections).

The second step is automatically executed after having updated the controller, by default triggering a rolling update of every deployed PostgreSQL instance to use the new instance manager. The rolling update procedure culminates with a switchover, which is controlled by the primaryUpdateStrategy option, by default set to unsupervised. When set to supervised, users need to complete the rolling update by manually promoting a new instance through the cnpg plugin for kubectl.

Since version 1.10.0, the rolling update behavior can be replaced with in-place updates of the instance manager. The latter don't require a restart of the PostgreSQL instance and, as a result, a switchover in the cluster. This behavior, which is disabled by default, is described below.

In-place updates of the instance manager

By default, CloudNativePG issues a rolling update of the cluster every time the operator is updated. The new instance manager shipped with the operator is added to each PostgreSQL pod via an init container.

However, this behavior can be changed via configuration to enable in-place updates of the instance manager, which is the PID 1 process that keeps the container alive.

Internally, any instance manager from version 1.10 of CloudNativePG supports injection of a new executable that will replace the existing one, once the integrity verification phase is completed, as well as graceful termination of all the internal processes. When the new instance manager restarts using the new binary, it adopts the already running postmaster.

As a result, the PostgreSQL process is unaffected by the update, refraining from the need to perform a switchover. The other side of the coin, is that the Pod is changed after the start, breaking the pure concept of immutability.

You can enable this feature by setting the ENABLE_INSTANCE_MANAGER_INPLACE_UPDATES environment variable to 'true' in the operator configuration.

The in-place upgrade process will not change the init container image inside the Pods. Therefore, the Pod definition will not reflect the current version of the operator.

Compatibility among versions

CloudNativePG follows semantic versioning. Every release of the operator within the same API version is compatible with the previous one. The current API version is v1, corresponding to versions 1.x.y of the operator.

In addition to new features, new versions of the operator contain bug fixes and stability enhancements. Because of this, we strongly encourage users to upgrade to the latest version of the operator, as each version is released in order to maintain the most secure and stable Postgres environment.

CloudNativePG currently releases new versions of the operator at least monthly. If you are unable to apply updates as each version becomes available, we recommend upgrading through each version in sequential order to come current periodically and not skipping versions.

The release notes page contains a detailed list of the changes introduced in every released version of CloudNativePG, and it must be read before upgrading to a newer version of the software.

Most versions are directly upgradable and in that case, applying the newer manifest for plain Kubernetes installations or using the native package manager of the chosen distribution is enough.

When versions are not directly upgradable, the old version needs to be removed before installing the new one. This won't affect user data but only the operator itself.

Upgrading to 1.24.0 or 1.23.3

From Replica Clusters to Distributed Topology

One of the key enhancements in CloudNativePG 1.24.0 is the upgrade of the replica cluster feature.

The former replica cluster feature, now referred to as the "Standalone Replica Cluster," is no longer recommended for Disaster Recovery (DR) and High Availability (HA) scenarios that span multiple Kubernetes clusters. Standalone replica clusters are best suited for read-only workloads, such as reporting, OLAP, or creating development environments with test data.

For DR and HA purposes, CloudNativePG now introduces the Distributed Topology strategy for replica clusters. This new strategy allows you to build PostgreSQL clusters across private, public, hybrid, and multi-cloud environments, spanning multiple regions and potentially different cloud providers. It also provides an API to control the switchover operation, ensuring that only one cluster acts as the primary at any given time.

This Distributed Topology strategy enhances resilience and scalability, making it a robust solution for modern, distributed applications that require high availability and disaster recovery capabilities across diverse infrastructure setups.

You can seamlessly transition from a previous replica cluster configuration to a distributed topology by modifying all the Cluster resources involved in the distributed PostgreSQL setup. Ensure the following steps are taken:

• Configure the externalClusters section to include all the clusters involved in the distributed topology. We strongly suggest using the same configuration across all Cluster resources for maintainability and consistency.
• Configure the primary and source fields in the .spec.replica stanza to reflect the distributed topology. The primary field should contain the name of the current primary cluster in the distributed topology, while the source field should contain the name of the cluster each Cluster resource is replicating from. It is important to note that the enabled field, which was previously set to true or false, should now be unset (default).

For more information, please refer to the "Distributed Topology" section for replica clusters.

Upgrading to 1.23 from a previous minor version

User defined replication slots

CloudNativePG now offers automated synchronization of all replication slots defined on the primary to any standby within the High Availability (HA) cluster.

If you manually manage replication slots on a standby, it is essential to exclude those replication slots from synchronization. Failure to do so may result in CloudNativePG removing them from the standby. To implement this exclusion, utilize the following YAML configuration. In this example, replication slots with a name starting with 'foo' are prevented from synchronization:

...
  replicationSlots:
    synchronizeReplicas:
      enabled: true
      excludePatterns:
      - "^foo"

Alternatively, if you prefer to disable the synchronization mechanism entirely, use the following configuration:

...
  replicationSlots:
    synchronizeReplicas:
      enabled: false

Server-side apply of manifests

To ensure compatibility with Kubernetes 1.29 and upcoming versions, CloudNativePG now mandates the utilization of "Server-side apply" when deploying the operator manifest.

While employing this installation method poses no challenges for new deployments, updating existing operator manifests using the --server-side option may result in errors resembling the example below:

Apply failed with 1 conflict: conflict with "kubectl-client-side-apply" using..

If such errors arise, they can be resolved by explicitly specifying the --force-conflicts option to enforce conflict resolution:

kubectl apply --server-side --force-conflicts -f <OPERATOR_MANIFEST>

Henceforth, kube-apiserver will be automatically acknowledged as a recognized manager for the CRDs, eliminating the need for any further manual intervention on this matter.

Upgrading to 1.22 from a previous minor version

CloudNativePG continues to adhere to the security-by-default approach. As of version 1.22, the usage of the ALTER SYSTEM command is now disabled by default.

The reason behind this choice is to ensure that, by default, changes to the PostgreSQL configuration in a database cluster controlled by CloudNativePG are allowed only through the Kubernetes API.

At the same time, we are providing an option to enable ALTER SYSTEM if you need to use it, even temporarily, from versions 1.22.0, 1.21.2, and 1.20.5, by setting .spec.postgresql.enableAlterSystem to true, as in the following excerpt:

...
  postgresql:
    enableAlterSystem: true
...

Clusters in 1.22 will have enableAlterSystem set to false by default. If you want to retain the existing behavior in 1.22, you need to explicitly set enableAlterSystem to true as shown above.