cnpg-i-hello-world

README

CNPG-I Hello World Plugin

A CNPG-I plugin to add user-defined labels, annotations and a specific pause sidecar to the pods of CloudNativePG clusters.

This project serves as an introductory guide to bootstrapping a CNPG-I plugin and leveraging lifecycle hooks within a development environment. While similar results can be achieved through simpler methods such as mutating webhooks or CNPG's built-in features, this project is specifically designed to familiarize developers with the plugin workflow. By understanding how lifecycle hooks interact with other interfaces, developers can gain a deeper insight into implementing complex resource changes in real-world applications.

This plugin uses the pluginhelper from cnpg-i-machinery to simplify the plugin's implementation.

Running the plugin

To see the plugin in execution, you need to have a Kubernetes cluster running (we'll use Kind) and the CloudNativePG operator installed. The plugin also requires certificates to communicate with the operator, hence we are also installing cert-manager to manage them.

kind create cluster --name cnpg-i-hello-world
# Choose the latest version of CloudNativePG (at least 1.24)
kubectl apply --server-side -f \
  https://github.com/cloudnative-pg/cloudnative-pg/releases/download/vX.Y.Z/cnpg-X.Y.Z.yaml
# Choose the latest version of cert-manager
kubectl apply -f \
  https://github.com/cert-manager/cert-manager/releases/download/vX.Y.Z/cert-manager.yaml

Then install the plugin by applying the manifest:

kubectl apply -f https://github.com/cloudnative-pg/cnpg-i-hello-world/releases/download/v0.1.0/manifest.yaml

Finally, create a cluster resource to see the plugin in action. There are three examples in the doc/examples directory:

1. Cluster with labels and annotations: adds the defined labels and annotations to the pods. Showcases the plugin capability of altering the lifecycle of the CloudNativePG resources.
2. Cluster with no parameters: defaults the plugin settings of the cluster. Showcases the plugin capability of altering the defaulting webhook behavior.
3. Cluster with wrong parameters: includes an error in the configuration. Showcases the plugin capability of validating its own configuration.

Plugin development

For additional details on the plugin implementation refer to the development documentation.

Documentation

Overview

Package main is the entrypoint of the application