templateAgentAddon.md

Overview

This doc is used to introduce how to create an AddOn using Go template.

Steps

We have an example in helloworld.

1. Need to import templates files into embed.FS.
2. Create and start templateAgentAddon instance like this:

   mgr, err := addonmanager.New(controllerContext.KubeConfig)
    if err != nil {
    	return err
    }
   
    agentAddon, err := addonfactory.NewAgentAddonFactory(addonName, FS, "manifests/templates").
    	WithGetValuesFuncs(getValues, addonfactory.GetValuesFromAddonAnnotation).
    	WithAgentRegistrationOption(registrationOption).
    	BuildTemplateAgentAddon()
    if err != nil {
    	return err
    }
   
    mgr.AddAgent(agentAddon)
    mgr.Start(ctx)

Values definition

We also name the config for the template as Values.

Built-in Values

AddOn built-in values

• ClusterName
• AddonInstallNamespace
• HubKubeConfigSecret (used when the AddOn is needed to register to the Hub cluster)

In the list of GetValuesFuncs, the values from the big index Func will override the one from low index Func. The built-in Values will override the Values got from the list of GetValuesFuncs.

The config variable names should begin with uppercase. We can use StructToValues to convert config struct to Values.

Values from annotation of ManagedClusterAddon

We support a helper GetValuesFunc named GetValuesFromAddonAnnotation which can get values from annotation of ManagedClusterAddon. The key of Values in annotation is addon.open-cluster-management.io/values, and the value should be a valid json string which has key-value format.