Kubernetes API Server Patterns

This skill covers patterns for building Kubernetes aggregated API servers and understanding when to choose this approach over CRD-based controllers.

Overview

Datum Cloud services are Kubernetes aggregated API servers, not CRD-based controllers. This means:

• •Custom storage backends (not etcd)
• •Direct REST handler implementation
• •Scheme registration and API installation
• •APIService registration

Important: Before implementing a new service, read architecture-decision.md to understand why aggregated API servers were chosen and when CRD-based controllers might be appropriate.

Key Files

Core Patterns

REST Handler Structure

type REST struct {
    store       storage.Interface
    TableConvertor
    *genericregistry.Store
}

func NewREST(store storage.Interface) (*REST, *StatusREST) {
    r := &REST{store: store}
    statusStore := &StatusREST{store: store}
    return r, statusStore
}

Storage Interface

Use rest.Storage, NOT rest.StandardStorage:

var _ rest.Storage = &REST{}
var _ rest.Creater = &REST{}
var _ rest.Updater = &REST{}
var _ rest.GracefulDeleter = &REST{}
var _ rest.Lister = &REST{}
var _ rest.Getter = &REST{}
var _ rest.Watcher = &REST{}

Scheme Registration

Explicit Install() not init():

func Install(scheme *runtime.Scheme) {
    utilruntime.Must(v1alpha1.AddToScheme(scheme))
    utilruntime.Must(scheme.SetVersionPriority(v1alpha1.SchemeGroupVersion))
}

Scaffolding Scripts

Validation

Run scripts/validate-types.sh to check:

• •TypeMeta and ObjectMeta present
• •Spec and Status separation
• •List type has Items
• •Deepcopy markers present

Related Files

• •types.md — Type definitions
• •storage.md — Storage patterns
• •validation.md — Validation patterns
• •server-config.md — Server setup