controllerruntime

README

Kubernetes controller-runtime Project

The Kubernetes controller-runtime Project is a set of go libraries for building Controllers.

Documentation:

• Package overview
• Basic controller using builder
• Creating a manager
• Creating a controller
• Example main.go

Versioning, Maintenance, and Compatibility

The full documentation can be found at VERSIONING.md, but TL;DR:

Users:

• We follow Semantic Versioning (semver)
• Use releases with your dependency management to ensure that you get compatible code
• The master branch contains all the latest code, some of which may break compatibility (so "normal" go get is not reccomended)

Contributors:

• All code PR must be labeled with 🐛 (patch fixes), ✨ (backwards-compatible features), or ⚠ (breaking changes)
• Breaking changes will find their way into the next major release, other changes will go into an semi-immediate patch or minor release
• For a quick PR template suggesting the right information, use one of these PR templates:
  • Breaking Changes/Features
  • Backwards-Compatible Features
  • Bug fixes
  • Documentation Changes
  • Test/Build/Other Changes

Community, discussion, contribution, and support

Learn how to engage with the Kubernetes community on the community page.

controller-runtime is a subproject of the kubebuilder project in sig apimachinery.

You can reach the maintainers of this project at:

• Slack channel: #kubebuilder
• Google Group: kubebuilder@googlegroups.com

Contributing

Contributions are greatly appreciated. The maintainers actively manage the issues list, and try to highlight issues suitable for newcomers. The project follows the typical GitHub pull request model. See CONTRIBUTING.md for more details. Before starting any work, please either comment on an existing issue, or file a new one.

Code of conduct

Participation in the Kubernetes community is governed by the Kubernetes Code of Conduct.

Documentation

Overview

Package controllerruntime alias' common functions and types to improve discoverability and reduce the number of imports for simple Controllers.

Example

This example creates a simple application Controller that is configured for ReplicaSets and Pods.

* Create a new application for ReplicaSets that manages Pods owned by the ReplicaSet and calls into ReplicaSetReconciler.

* Start the application. TODO(pwittrock): Update this example when we have better dependency injection support

package main

import (
	"context"
	"fmt"
	"os"

	appsv1 "k8s.io/api/apps/v1"
	corev1 "k8s.io/api/core/v1"
	controllers "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/client"
)

// This example creates a simple application Controller that is configured for ReplicaSets and Pods.
//
// * Create a new application for ReplicaSets that manages Pods owned by the ReplicaSet and calls into
// ReplicaSetReconciler.
//
// * Start the application.
// TODO(pwittrock): Update this example when we have better dependency injection support
func main() {
	var log = controllers.Log.WithName("builder-examples")

	manager, err := controllers.NewManager(controllers.GetConfigOrDie(), controllers.Options{})
	if err != nil {
		log.Error(err, "could not create manager")
		os.Exit(1)
	}

	err = controllers.
		NewControllerManagedBy(manager). // Create the Controller
		For(&appsv1.ReplicaSet{}).       // ReplicaSet is the Application API
		Owns(&corev1.Pod{}).             // ReplicaSet owns Pods created by it
		Complete(&ReplicaSetReconciler{Client: manager.GetClient()})
	if err != nil {
		log.Error(err, "could not create controller")
		os.Exit(1)
	}

	if err := manager.Start(controllers.SetupSignalHandler()); err != nil {
		log.Error(err, "could not start manager")
		os.Exit(1)
	}
}

// ReplicaSetReconciler is a simple Controller example implementation.
type ReplicaSetReconciler struct {
	client.Client
}

// Implement the business logic:
// This function will be called when there is a change to a ReplicaSet or a Pod with an OwnerReference
// to a ReplicaSet.
//
// * Read the ReplicaSet
// * Read the Pods
// * Set a Label on the ReplicaSet with the Pod count
func (a *ReplicaSetReconciler) Reconcile(req controllers.Request) (controllers.Result, error) {
	// Read the ReplicaSet
	rs := &appsv1.ReplicaSet{}
	err := a.Get(context.TODO(), req.NamespacedName, rs)
	if err != nil {
		return controllers.Result{}, err
	}

	// List the Pods matching the PodTemplate Labels
	pods := &corev1.PodList{}
	err = a.List(context.TODO(), client.InNamespace(req.Namespace).MatchingLabels(rs.Spec.Template.Labels), pods)
	if err != nil {
		return controllers.Result{}, err
	}

	// Update the ReplicaSet
	rs.Labels["pod-count"] = fmt.Sprintf("%v", len(pods.Items))
	err = a.Update(context.TODO(), rs)
	if err != nil {
		return controllers.Result{}, err
	}

	return controllers.Result{}, nil
}

Index

• Variables
• type Builder
• type GroupResource
• type GroupVersion
• type Manager
• type ObjectMeta
• type Options
• type Request
• type Result
• type SchemeBuilder
• type TypeMeta

Examples

• Package

Variables

var (
	// GetConfigOrDie creates a *rest.Config for talking to a Kubernetes apiserver.
	// If --kubeconfig is set, will use the kubeconfig file at that location.  Otherwise will assume running
	// in cluster and use the cluster provided kubeconfig.
	//
	// Will log an error and exit if there is an error creating the rest.Config.
	GetConfigOrDie = config.GetConfigOrDie

	// GetConfig creates a *rest.Config for talking to a Kubernetes apiserver.
	// If --kubeconfig is set, will use the kubeconfig file at that location.  Otherwise will assume running
	// in cluster and use the cluster provided kubeconfig.
	//
	// Config precedence
	//
	// * --kubeconfig flag pointing at a file
	//
	// * KUBECONFIG environment variable pointing at a file
	//
	// * In-cluster config if running in cluster
	//
	// * $HOME/.kube/config if exists
	GetConfig = config.GetConfig

	// NewControllerManagedBy returns a new controller builder that will be started by the provided Manager
	NewControllerManagedBy = builder.ControllerManagedBy

	// NewManager returns a new Manager for creating Controllers.
	NewManager = manager.New

	// CreateOrUpdate creates or updates the given object obj in the Kubernetes
	// cluster. The object's desired state should be reconciled with the existing
	// state using the passed in ReconcileFn. obj must be a struct pointer so that
	// obj can be updated with the content returned by the Server.
	//
	// It returns the executed operation and an error.
	CreateOrUpdate = controllerutil.CreateOrUpdate

	// SetControllerReference sets owner as a Controller OwnerReference on owned.
	// This is used for garbage collection of the owned object and for
	// reconciling the owner object on changes to owned (with a Watch + EnqueueRequestForOwner).
	// Since only one OwnerReference can be a controller, it returns an error if
	// there is another OwnerReference with Controller flag set.
	SetControllerReference = controllerutil.SetControllerReference

	// SetupSignalHandler registered for SIGTERM and SIGINT. A stop channel is returned
	// which is closed on one of these signals. If a second signal is caught, the program
	// is terminated with exit code 1.
	SetupSignalHandler = signals.SetupSignalHandler

	// Log is the base logger used by controller-runtime.  It delegates
	// to another logr.Logger.  You *must* call SetLogger to
	// get any actual logging.
	Log = log.Log

	// SetLogger sets a concrete logging implementation for all deferred Loggers.
	SetLogger = log.SetLogger

	// ZapLogger is a Logger implementation.
	// If development is true, a Zap development config will be used
	// (stacktraces on warnings, no sampling), otherwise a Zap production
	// config will be used (stacktraces on errors, sampling).
	ZapLogger = log.ZapLogger
)

Types

type Builder

type Builder = builder.Builder

Builder builds an Application ControllerManagedBy (e.g. Operator) and returns a manager.Manager to start it.

type GroupResource

type GroupResource = schema.GroupResource

GroupResource specifies a Group and a Resource, but does not force a version. This is useful for identifying concepts during lookup stages without having partially valid types

type GroupVersion

type GroupVersion = schema.GroupVersion

GroupVersion contains the "group" and the "version", which uniquely identifies the API.

type Manager

type Manager = manager.Manager

Manager initializes shared dependencies such as Caches and Clients, and provides them to Runnables. A Manager is required to create Controllers.

type ObjectMeta

type ObjectMeta = metav1.ObjectMeta

ObjectMeta is metadata that all persisted resources must have, which includes all objects users must create.

type Options

type Options = manager.Options

Options are the arguments for creating a new Manager

type Request

type Request = reconcile.Request

Request contains the information necessary to reconcile a Kubernetes object. This includes the information to uniquely identify the object - its Name and Namespace. It does NOT contain information about any specific Event or the object contents itself.

type Result

type Result = reconcile.Result

Result contains the result of a Reconciler invocation.

type SchemeBuilder

type SchemeBuilder = scheme.Builder

Builder builds a new Scheme for mapping go types to Kubernetes GroupVersionKinds.

type TypeMeta

type TypeMeta = metav1.TypeMeta

TypeMeta describes an individual object in an API response or request with strings representing the type of the object and its API schema version. Structures that are versioned or persisted should inline TypeMeta.

+k8s:deepcopy-gen=false