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 as follows:

kubectl apply -f \
  https://raw.githubusercontent.com/cloudnative-pg/cloudnative-pg/release-1.15/releases/cnpg-1.15.5.yaml

Once you have run the kubectl command, CloudNativePG will be installed in your Kubernetes cluster.

You can verify that with:

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

Using the Helm Chart

The operator can be installed using the provided Helm chart.

Details about the deployment

In Kubernetes, the operator is by default installed in the cnpg-system namespace as a Kubernetes Deployment called cnpg-controller-manager. You can get more information by running:

kubectl describe deploy \
  -n cnpg-system \
  cnpg-controller-manager

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.