controller

Documentation

Overview

Package controller provides types and functions for building Controllers. Controllers implement Kubernetes APIs.

Creation

To create a new Controller, first create a manager.Manager and pass it to the controller.New function. The Controller MUST be started by calling Manager.Start.

Index

• type Controller
  • func New(name string, mgr manager.Manager, options Options) (Controller, error)
  • func NewUnmanaged(name string, mgr manager.Manager, options Options) (Controller, error)
• type Options

Examples

• Controller
• Controller (Unstructured)
• New
• NewUnmanaged

Types

type Controller

type Controller interface {
	// Reconciler is called to reconcile an object by Namespace/Name
	reconcile.Reconciler

	// Watch takes events provided by a Source and uses the EventHandler to
	// enqueue reconcile.Requests in response to the events.
	//
	// Watch may be provided one or more Predicates to filter events before
	// they are given to the EventHandler.  Events will be passed to the
	// EventHandler if all provided Predicates evaluate to true.
	Watch(src source.Source, eventhandler handler.EventHandler, predicates ...predicate.Predicate) error

	// Start starts the controller.  Start blocks until the context is closed or a
	// controller has an error starting.
	Start(ctx context.Context) error
}

Controller implements a Kubernetes API. A Controller manages a work queue fed reconcile.Requests from source.Sources. Work is performed through the reconcile.Reconciler for each enqueued item. Work typically is reads and writes Kubernetes objects to make the system state match the state specified in the object Spec.

Example

This example starts a new Controller named "pod-controller" to Watch Pods and call a no-op Reconciler.

package main

import (
	"context"
	"os"

	corev1 "k8s.io/api/core/v1"
	"sigs.k8s.io/controller-runtime/pkg/controller"
	"sigs.k8s.io/controller-runtime/pkg/handler"

	logf "sigs.k8s.io/controller-runtime/pkg/log"
	"sigs.k8s.io/controller-runtime/pkg/manager"
	"sigs.k8s.io/controller-runtime/pkg/manager/signals"
	"sigs.k8s.io/controller-runtime/pkg/reconcile"
	"sigs.k8s.io/controller-runtime/pkg/source"
)

var (
	mgr manager.Manager

	log = logf.Log.WithName("controller-examples")
)

func main() {
	// mgr is a manager.Manager

	// Create a new Controller that will call the provided Reconciler function in response
	// to events.
	c, err := controller.New("pod-controller", mgr, controller.Options{
		Reconciler: reconcile.Func(func(context.Context, reconcile.Request) (reconcile.Result, error) {
			// Your business logic to implement the API by creating, updating, deleting objects goes here.
			return reconcile.Result{}, nil
		}),
	})
	if err != nil {
		log.Error(err, "unable to create pod-controller")
		os.Exit(1)
	}

	// Watch for Pod create / update / delete events and call Reconcile
	err = c.Watch(&source.Kind{Type: &corev1.Pod{}}, &handler.EnqueueRequestForObject{})
	if err != nil {
		log.Error(err, "unable to watch pods")
		os.Exit(1)
	}

	// Start the Controller through the manager.
	if err := mgr.Start(signals.SetupSignalHandler()); err != nil {
		log.Error(err, "unable to continue running manager")
		os.Exit(1)
	}
}

Example (Unstructured)

This example starts a new Controller named "pod-controller" to Watch Pods with the unstructured object and call a no-op Reconciler.

package main

import (
	"context"
	"os"

	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/apimachinery/pkg/runtime/schema"
	"sigs.k8s.io/controller-runtime/pkg/controller"
	"sigs.k8s.io/controller-runtime/pkg/handler"

	logf "sigs.k8s.io/controller-runtime/pkg/log"
	"sigs.k8s.io/controller-runtime/pkg/manager"
	"sigs.k8s.io/controller-runtime/pkg/manager/signals"
	"sigs.k8s.io/controller-runtime/pkg/reconcile"
	"sigs.k8s.io/controller-runtime/pkg/source"
)

var (
	mgr manager.Manager

	log = logf.Log.WithName("controller-examples")
)

func main() {
	// mgr is a manager.Manager

	// Create a new Controller that will call the provided Reconciler function in response
	// to events.
	c, err := controller.New("pod-controller", mgr, controller.Options{
		Reconciler: reconcile.Func(func(context.Context, reconcile.Request) (reconcile.Result, error) {
			// Your business logic to implement the API by creating, updating, deleting objects goes here.
			return reconcile.Result{}, nil
		}),
	})
	if err != nil {
		log.Error(err, "unable to create pod-controller")
		os.Exit(1)
	}

	u := &unstructured.Unstructured{}
	u.SetGroupVersionKind(schema.GroupVersionKind{
		Kind:    "Pod",
		Group:   "",
		Version: "v1",
	})
	// Watch for Pod create / update / delete events and call Reconcile
	err = c.Watch(&source.Kind{Type: u}, &handler.EnqueueRequestForObject{})
	if err != nil {
		log.Error(err, "unable to watch pods")
		os.Exit(1)
	}

	// Start the Controller through the manager.
	if err := mgr.Start(signals.SetupSignalHandler()); err != nil {
		log.Error(err, "unable to continue running manager")
		os.Exit(1)
	}
}

func New

func New(name string, mgr manager.Manager, options Options) (Controller, error)

New returns a new Controller registered with the Manager. The Manager will ensure that shared Caches have been synced before the Controller is Started.

Example

This example creates a new Controller named "pod-controller" with a no-op reconcile function. The manager.Manager will be used to Start the Controller, and will provide it a shared Cache and Client.

package main

import (
	"context"
	"os"

	"sigs.k8s.io/controller-runtime/pkg/controller"

	logf "sigs.k8s.io/controller-runtime/pkg/log"
	"sigs.k8s.io/controller-runtime/pkg/manager"
	"sigs.k8s.io/controller-runtime/pkg/reconcile"
)

var (
	mgr manager.Manager

	log = logf.Log.WithName("controller-examples")
)

func main() {
	_, err := controller.New("pod-controller", mgr, controller.Options{
		Reconciler: reconcile.Func(func(context.Context, reconcile.Request) (reconcile.Result, error) {
			// Your business logic to implement the API by creating, updating, deleting objects goes here.
			return reconcile.Result{}, nil
		}),
	})
	if err != nil {
		log.Error(err, "unable to create pod-controller")
		os.Exit(1)
	}
}

func NewUnmanaged

func NewUnmanaged(name string, mgr manager.Manager, options Options) (Controller, error)

NewUnmanaged returns a new controller without adding it to the manager. The caller is responsible for starting the returned controller.

Example

This example creates a new controller named "pod-controller" to watch Pods and call a no-op reconciler. The controller is not added to the provided manager, and must thus be started and stopped by the caller.

package main

import (
	"context"
	"os"

	corev1 "k8s.io/api/core/v1"
	"sigs.k8s.io/controller-runtime/pkg/controller"
	"sigs.k8s.io/controller-runtime/pkg/handler"

	logf "sigs.k8s.io/controller-runtime/pkg/log"
	"sigs.k8s.io/controller-runtime/pkg/manager"
	"sigs.k8s.io/controller-runtime/pkg/reconcile"
	"sigs.k8s.io/controller-runtime/pkg/source"
)

var (
	mgr manager.Manager

	log = logf.Log.WithName("controller-examples")
)

func main() {
	// mgr is a manager.Manager

	// Configure creates a new controller but does not add it to the supplied
	// manager.
	c, err := controller.NewUnmanaged("pod-controller", mgr, controller.Options{
		Reconciler: reconcile.Func(func(context.Context, reconcile.Request) (reconcile.Result, error) {
			return reconcile.Result{}, nil
		}),
	})
	if err != nil {
		log.Error(err, "unable to create pod-controller")
		os.Exit(1)
	}

	if err := c.Watch(&source.Kind{Type: &corev1.Pod{}}, &handler.EnqueueRequestForObject{}); err != nil {
		log.Error(err, "unable to watch pods")
		os.Exit(1)
	}

	ctx, cancel := context.WithCancel(context.Background())

	// Start our controller in a goroutine so that we do not block.
	go func() {
		// Block until our controller manager is elected leader. We presume our
		// entire process will terminate if we lose leadership, so we don't need
		// to handle that.
		<-mgr.Elected()

		// Start our controller. This will block until the context is
		// closed, or the controller returns an error.
		if err := c.Start(ctx); err != nil {
			log.Error(err, "cannot run experiment controller")
		}
	}()

	// Stop our controller.
	cancel()
}

type Options

type Options struct {
	// MaxConcurrentReconciles is the maximum number of concurrent Reconciles which can be run. Defaults to 1.
	MaxConcurrentReconciles int

	// Reconciler reconciles an object
	Reconciler reconcile.Reconciler

	// RateLimiter is used to limit how frequently requests may be queued.
	// Defaults to MaxOfRateLimiter which has both overall and per-item rate limiting.
	// The overall is a token bucket and the per-item is exponential.
	RateLimiter ratelimiter.RateLimiter

	// Log is the logger used for this controller and passed to each reconciliation
	// request via the context field.
	Log logr.Logger
}

Options are the arguments for creating a new Controller