build_controller.go

package build

import (
	"fmt"
	"strings"
	"sync"
	"time"

	"github.com/golang/glog"
	metrics "github.com/openshift/origin/pkg/build/metrics/prometheus"
	"k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	utilerrors "k8s.io/apimachinery/pkg/util/errors"
	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
	"k8s.io/apimachinery/pkg/util/validation/field"
	"k8s.io/apimachinery/pkg/util/wait"
	v1core "k8s.io/client-go/kubernetes/typed/core/v1"
	clientv1 "k8s.io/client-go/pkg/api/v1"
	"k8s.io/client-go/tools/cache"
	"k8s.io/client-go/tools/record"
	"k8s.io/client-go/util/workqueue"
	kapi "k8s.io/kubernetes/pkg/api"
	"k8s.io/kubernetes/pkg/api/v1"
	kexternalclientset "k8s.io/kubernetes/pkg/client/clientset_generated/clientset"
	kexternalcoreclient "k8s.io/kubernetes/pkg/client/clientset_generated/clientset/typed/core/v1"
	kclientset "k8s.io/kubernetes/pkg/client/clientset_generated/internalclientset"
	kexternalcoreinformers "k8s.io/kubernetes/pkg/client/informers/informers_generated/externalversions/core/v1"
	v1lister "k8s.io/kubernetes/pkg/client/listers/core/v1"

	"github.com/openshift/origin/pkg/api/meta"
	buildapi "github.com/openshift/origin/pkg/build/apis/build"
	"github.com/openshift/origin/pkg/build/apis/build/validation"
	buildclient "github.com/openshift/origin/pkg/build/client"
	builddefaults "github.com/openshift/origin/pkg/build/controller/build/defaults"
	buildoverrides "github.com/openshift/origin/pkg/build/controller/build/overrides"
	"github.com/openshift/origin/pkg/build/controller/common"
	"github.com/openshift/origin/pkg/build/controller/policy"
	"github.com/openshift/origin/pkg/build/controller/strategy"
	buildinformer "github.com/openshift/origin/pkg/build/generated/informers/internalversion/build/internalversion"
	buildinternalclient "github.com/openshift/origin/pkg/build/generated/internalclientset"
	buildlister "github.com/openshift/origin/pkg/build/generated/listers/build/internalversion"
	buildgenerator "github.com/openshift/origin/pkg/build/generator"
	buildutil "github.com/openshift/origin/pkg/build/util"
	"github.com/openshift/origin/pkg/cmd/server/bootstrappolicy"
	imageapi "github.com/openshift/origin/pkg/image/apis/image"
	imageinformers "github.com/openshift/origin/pkg/image/generated/informers/internalversion/image/internalversion"
	imagelister "github.com/openshift/origin/pkg/image/generated/listers/image/internalversion"
)

const (
	maxRetries = 15

	// maxExcerptLength is the maximum length of the LogSnippet on a build.
	maxExcerptLength = 5
)

// resourceTriggerQueue tracks a set of resource keys to trigger when another object changes.
type resourceTriggerQueue struct {
	lock  sync.Mutex
	queue map[string][]string
}

// newResourceTriggerQueue creates a resourceTriggerQueue.
func newResourceTriggerQueue() *resourceTriggerQueue {
	return &resourceTriggerQueue{
		queue: make(map[string][]string),
	}
}

// Add ensures resource will be returned the next time any of on are invoked
// on Pop().
func (q *resourceTriggerQueue) Add(resource string, on []string) {
	q.lock.Lock()
	defer q.lock.Unlock()
	for _, key := range on {
		q.queue[key] = append(q.queue[key], resource)
	}
}

func (q *resourceTriggerQueue) Remove(resource string, on []string) {
	q.lock.Lock()
	defer q.lock.Unlock()
	for _, key := range on {
		resources := q.queue[key]
		newResources := make([]string, 0, len(resources))
		for _, existing := range resources {
			if existing == resource {
				continue
			}
			newResources = append(newResources, existing)
		}
		q.queue[key] = newResources
	}
}

func (q *resourceTriggerQueue) Pop(key string) []string {
	q.lock.Lock()
	defer q.lock.Unlock()
	resources := q.queue[key]
	delete(q.queue, key)
	return resources
}

// BuildController watches builds and synchronizes them with their
// corresponding build pods. It is also responsible for resolving image
// stream references in the Build to docker images prior to invoking the pod.
// The build controller late binds image stream references so that users can
// create a build config before they create the image stream (or before
// an image is pushed to a tag) which allows actions to converge. It also
// allows multiple Build objects to directly reference images created by another
// Build, acting as a simple dependency graph for a logical multi-image build
// that reuses many individual Builds.
//
// Like other controllers that do "on behalf of" image resolution, the controller
// resolves the reference which allows users to see what image ID corresponds to a tag
// simply by requesting resolution. This is consistent with other image policy in the
// system (image tag references in deployments, triggers, and image policy). The only
// leaked image information is the ID which is considered acceptable. Secrets are also
// resolved, allowing a user in the same namespace to in theory infer the presence of
// a secret or make it usable by a build - but this is identical to our existing model
// where a service account determines access to secrets used in pods.
type BuildController struct {
	buildPatcher      buildclient.BuildPatcher
	buildLister       buildlister.BuildLister
	buildConfigGetter buildlister.BuildConfigLister
	buildDeleter      buildclient.BuildDeleter
	podClient         kexternalcoreclient.PodsGetter
	kubeClient        kclientset.Interface

	buildQueue       workqueue.RateLimitingInterface
	imageStreamQueue *resourceTriggerQueue
	buildConfigQueue workqueue.RateLimitingInterface

	buildStore       buildlister.BuildLister
	secretStore      v1lister.SecretLister
	podStore         v1lister.PodLister
	imageStreamStore imagelister.ImageStreamLister

	podInformer   cache.SharedIndexInformer
	buildInformer cache.SharedIndexInformer

	buildStoreSynced       func() bool
	podStoreSynced         func() bool
	secretStoreSynced      func() bool
	imageStreamStoreSynced func() bool

	runPolicies    []policy.RunPolicy
	createStrategy buildPodCreationStrategy
	buildDefaults  builddefaults.BuildDefaults
	buildOverrides buildoverrides.BuildOverrides

	recorder record.EventRecorder
}

// BuildControllerParams is the set of parameters needed to
// create a new BuildController
type BuildControllerParams struct {
	BuildInformer       buildinformer.BuildInformer
	BuildConfigInformer buildinformer.BuildConfigInformer
	ImageStreamInformer imageinformers.ImageStreamInformer
	PodInformer         kexternalcoreinformers.PodInformer
	SecretInformer      kexternalcoreinformers.SecretInformer
	KubeClientInternal  kclientset.Interface
	KubeClientExternal  kexternalclientset.Interface
	BuildClientInternal buildinternalclient.Interface
	DockerBuildStrategy *strategy.DockerBuildStrategy
	SourceBuildStrategy *strategy.SourceBuildStrategy
	CustomBuildStrategy *strategy.CustomBuildStrategy
	BuildDefaults       builddefaults.BuildDefaults
	BuildOverrides      buildoverrides.BuildOverrides
}

// NewBuildController creates a new BuildController.
func NewBuildController(params *BuildControllerParams) *BuildController {
	eventBroadcaster := record.NewBroadcaster()
	eventBroadcaster.StartRecordingToSink(&v1core.EventSinkImpl{Interface: v1core.New(params.KubeClientExternal.Core().RESTClient()).Events("")})

	buildClient := buildclient.NewClientBuildClient(params.BuildClientInternal)
	buildLister := params.BuildInformer.Lister()
	buildConfigGetter := params.BuildConfigInformer.Lister()
	c := &BuildController{
		buildPatcher:      buildClient,
		buildLister:       buildLister,
		buildConfigGetter: buildConfigGetter,
		buildDeleter:      buildClient,
		secretStore:       params.SecretInformer.Lister(),
		podClient:         params.KubeClientExternal.Core(),
		kubeClient:        params.KubeClientInternal,
		podInformer:       params.PodInformer.Informer(),
		podStore:          params.PodInformer.Lister(),
		buildInformer:     params.BuildInformer.Informer(),
		buildStore:        params.BuildInformer.Lister(),
		imageStreamStore:  params.ImageStreamInformer.Lister(),
		createStrategy: &typeBasedFactoryStrategy{
			dockerBuildStrategy: params.DockerBuildStrategy,
			sourceBuildStrategy: params.SourceBuildStrategy,
			customBuildStrategy: params.CustomBuildStrategy,
		},
		buildDefaults:  params.BuildDefaults,
		buildOverrides: params.BuildOverrides,

		buildQueue:       workqueue.NewRateLimitingQueue(workqueue.DefaultControllerRateLimiter()),
		imageStreamQueue: newResourceTriggerQueue(),
		buildConfigQueue: workqueue.NewRateLimitingQueue(workqueue.DefaultControllerRateLimiter()),

		recorder:    eventBroadcaster.NewRecorder(kapi.Scheme, clientv1.EventSource{Component: "build-controller"}),
		runPolicies: policy.GetAllRunPolicies(buildLister, buildClient),
	}

	c.podInformer.AddEventHandler(cache.ResourceEventHandlerFuncs{
		UpdateFunc: c.podUpdated,
		DeleteFunc: c.podDeleted,
	})
	c.buildInformer.AddEventHandler(cache.ResourceEventHandlerFuncs{
		AddFunc:    c.buildAdded,
		UpdateFunc: c.buildUpdated,
	})
	params.ImageStreamInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
		AddFunc:    c.imageStreamAdded,
		UpdateFunc: c.imageStreamUpdated,
	})

	c.buildStoreSynced = c.buildInformer.HasSynced
	c.podStoreSynced = c.podInformer.HasSynced
	c.secretStoreSynced = params.SecretInformer.Informer().HasSynced
	c.imageStreamStoreSynced = params.ImageStreamInformer.Informer().HasSynced

	return c
}

// Run begins watching and syncing.
func (bc *BuildController) Run(workers int, stopCh <-chan struct{}) {
	defer utilruntime.HandleCrash()
	defer bc.buildQueue.ShutDown()
	defer bc.buildConfigQueue.ShutDown()

	// Wait for the controller stores to sync before starting any work in this controller.
	if !cache.WaitForCacheSync(stopCh, bc.buildStoreSynced, bc.podStoreSynced, bc.secretStoreSynced, bc.imageStreamStoreSynced) {
		utilruntime.HandleError(fmt.Errorf("timed out waiting for caches to sync"))
		return
	}

	glog.Infof("Starting build controller")

	for i := 0; i < workers; i++ {
		go wait.Until(bc.buildWorker, time.Second, stopCh)
	}

	for i := 0; i < workers; i++ {
		go wait.Until(bc.buildConfigWorker, time.Second, stopCh)
	}

	metrics.IntializeMetricsCollector(bc.buildLister)

	<-stopCh
	glog.Infof("Shutting down build controller")
}

func (bc *BuildController) buildWorker() {
	for {
		if quit := bc.buildWork(); quit {
			return
		}
	}
}

// buildWork gets the next build from the buildQueue and invokes handleBuild on it
func (bc *BuildController) buildWork() bool {
	key, quit := bc.buildQueue.Get()
	if quit {
		return true
	}

	defer bc.buildQueue.Done(key)

	build, err := bc.getBuildByKey(key.(string))
	if err != nil {
		bc.handleBuildError(err, key)
		return false
	}
	if build == nil {
		return false
	}

	err = bc.handleBuild(build)
	bc.handleBuildError(err, key)
	return false
}

func (bc *BuildController) buildConfigWorker() {
	for {
		if quit := bc.buildConfigWork(); quit {
			return
		}
	}
}

// buildConfigWork gets the next build config from the buildConfigQueue and invokes handleBuildConfig on it
func (bc *BuildController) buildConfigWork() bool {
	key, quit := bc.buildConfigQueue.Get()
	if quit {
		return true
	}
	defer bc.buildConfigQueue.Done(key)

	namespace, name, err := parseBuildConfigKey(key.(string))
	if err != nil {
		utilruntime.HandleError(err)
		return false
	}

	err = bc.handleBuildConfig(namespace, name)
	bc.handleBuildConfigError(err, key)
	return false
}

func parseBuildConfigKey(key string) (string, string, error) {
	parts := strings.SplitN(key, "/", 2)
	if len(parts) != 2 {
		return "", "", fmt.Errorf("invalid build config key: %s", key)
	}
	return parts[0], parts[1], nil
}

// handleBuild retrieves the build's corresponding pod and calls the appropriate
// handle function based on the build's current state. Each handler returns a buildUpdate
// object that includes any updates that need to be made on the build.
func (bc *BuildController) handleBuild(build *buildapi.Build) error {
	if shouldIgnore(build) {
		return nil
	}

	glog.V(4).Infof("Handling build %s", buildDesc(build))

	pod, podErr := bc.podStore.Pods(build.Namespace).Get(buildapi.GetBuildPodName(build))

	// Technically the only error that is returned from retrieving the pod is the
	// NotFound error so this check should not be needed, but leaving here in case
	// that changes in the future.
	if podErr != nil && !errors.IsNotFound(podErr) {
		return podErr
	}

	var update *buildUpdate
	var err, updateErr error

	switch {
	case shouldCancel(build):
		update, err = bc.cancelBuild(build)
	case build.Status.Phase == buildapi.BuildPhaseNew:
		update, err = bc.handleNewBuild(build, pod)
	case build.Status.Phase == buildapi.BuildPhasePending,
		build.Status.Phase == buildapi.BuildPhaseRunning:
		update, err = bc.handleActiveBuild(build, pod)
	case buildutil.IsBuildComplete(build):
		update, err = bc.handleCompletedBuild(build, pod)
	}
	if update != nil && !update.isEmpty() {
		updateErr = bc.updateBuild(build, update, pod)
	}
	if err != nil {
		return err
	}
	if updateErr != nil {
		return updateErr
	}
	return nil
}

// shouldIgnore returns true if a build should be ignored by the controller.
// These include pipeline builds as well as builds that are in a terminal state.
// However if the build is either complete or failed and its completion timestamp
// has not been set, then it returns false so that the build's completion timestamp
// gets updated.
func shouldIgnore(build *buildapi.Build) bool {
	// If pipeline build, do nothing.
	// These builds are processed/updated/etc by the jenkins sync plugin
	if build.Spec.Strategy.JenkinsPipelineStrategy != nil {
		glog.V(4).Infof("Ignoring build %s with jenkins pipeline strategy", buildDesc(build))
		return true
	}

	// If a build is in a terminal state, ignore it; unless it is in a succeeded or failed
	// state and its completion time or logsnippet is not set, then we should at least attempt to set its
	// completion time and logsnippet if possible because the build pod may have put the build in
	// this state and it would have not set the completion timestamp or logsnippet data.
	if buildutil.IsBuildComplete(build) {
		switch build.Status.Phase {
		case buildapi.BuildPhaseComplete:
			if build.Status.CompletionTimestamp == nil {
				return false
			}
		case buildapi.BuildPhaseFailed:
			if build.Status.CompletionTimestamp == nil || len(build.Status.LogSnippet) == 0 {
				return false
			}
		}
		glog.V(4).Infof("Ignoring build %s in completed state", buildDesc(build))
		return true
	}

	return false
}

// shouldCancel returns true if a build is active and its cancellation flag is set
func shouldCancel(build *buildapi.Build) bool {
	return !buildutil.IsBuildComplete(build) && build.Status.Cancelled
}

// cancelBuild deletes a build pod and returns an update to mark the build as cancelled
func (bc *BuildController) cancelBuild(build *buildapi.Build) (*buildUpdate, error) {
	glog.V(4).Infof("Cancelling build %s", buildDesc(build))

	podName := buildapi.GetBuildPodName(build)
	err := bc.podClient.Pods(build.Namespace).Delete(podName, &metav1.DeleteOptions{})
	if err != nil && !errors.IsNotFound(err) {
		return nil, fmt.Errorf("could not delete build pod %s/%s to cancel build %s: %v", build.Namespace, podName, buildDesc(build), err)
	}

	return transitionToPhase(buildapi.BuildPhaseCancelled, buildapi.StatusReasonCancelledBuild, buildapi.StatusMessageCancelledBuild), nil
}

// handleNewBuild will check whether policy allows running the new build and if so, creates a pod
// for the build and returns an update to move it to the Pending phase
func (bc *BuildController) handleNewBuild(build *buildapi.Build, pod *v1.Pod) (*buildUpdate, error) {
	// If a pod was found, and it was created after the build was created, it
	// means that the build is active and its status should be updated
	if pod != nil {
		//TODO: Use a better way to determine whether the pod corresponds to the build (maybe using the owner field)
		if !pod.CreationTimestamp.Before(build.CreationTimestamp) {
			return bc.handleActiveBuild(build, pod)
		}
		// If a pod was created before the current build, move the build to error
		return transitionToPhase(buildapi.BuildPhaseError, buildapi.StatusReasonBuildPodExists, buildapi.StatusMessageBuildPodExists), nil
	}

	runPolicy := policy.ForBuild(build, bc.runPolicies)
	if runPolicy == nil {
		return nil, fmt.Errorf("unable to determine build policy for %s", buildDesc(build))
	}

	// The runPolicy decides whether to execute this build or not.
	if run, err := runPolicy.IsRunnable(build); err != nil || !run {
		return nil, err
	}

	return bc.createBuildPod(build)
}

// createPodSpec creates a pod spec for the given build, with all references already resolved.
func (bc *BuildController) createPodSpec(build *buildapi.Build) (*v1.Pod, error) {
	if build.Spec.Output.To != nil {
		build.Status.OutputDockerImageReference = build.Spec.Output.To.Name
	}

	// ensure the build object the pod sees starts with a clean set of reasons/messages,
	// rather than inheriting the potential "invalidoutputreference" message from the current
	// build state.  Otherwise when the pod attempts to update the build (e.g. with the git
	// revision information), it will re-assert the stale reason/message.
	build.Status.Reason = ""
	build.Status.Message = ""

	// Invoke the strategy to create a build pod.
	podSpec, err := bc.createStrategy.CreateBuildPod(build)
	if err != nil {
		if strategy.IsFatal(err) {
			return nil, &strategy.FatalError{Reason: fmt.Sprintf("failed to create a build pod spec for build %s/%s: %v", build.Namespace, build.Name, err)}
		}
		return nil, fmt.Errorf("failed to create a build pod spec for build %s/%s: %v", build.Namespace, build.Name, err)
	}
	if err := bc.buildDefaults.ApplyDefaults(podSpec); err != nil {
		return nil, fmt.Errorf("failed to apply build defaults for build %s/%s: %v", build.Namespace, build.Name, err)
	}
	if err := bc.buildOverrides.ApplyOverrides(podSpec); err != nil {
		return nil, fmt.Errorf("failed to apply build overrides for build %s/%s: %v", build.Namespace, build.Name, err)
	}

	// Handle resolving ValueFrom references in build environment variables
	if err := common.ResolveValueFrom(podSpec, bc.kubeClient); err != nil {
		return nil, err
	}
	return podSpec, nil
}

// resolveImageSecretAsReference returns a LocalObjectReference to a secret that should
// be able to push/pull at the image location.
// Note that we are using controller level permissions to resolve the secret,
// meaning users could theoretically define a build that references an imagestream they cannot
// see, and 1) get the docker image reference of that imagestream and 2) a reference to a secret
// associated with a service account that can push to that location.  However they still cannot view the secret,
// and ability to use a service account implies access to its secrets, so this is considered safe.
// Furthermore it's necessary to enable triggered builds since a triggered build is not "requested"
// by a particular user, so there are no user permissions to validate against in that case.
func (bc *BuildController) resolveImageSecretAsReference(build *buildapi.Build, imagename string) (*kapi.LocalObjectReference, error) {
	serviceAccount := build.Spec.ServiceAccount
	if len(serviceAccount) == 0 {
		serviceAccount = bootstrappolicy.BuilderServiceAccountName
	}
	builderSecrets, err := buildgenerator.FetchServiceAccountSecrets(bc.kubeClient.Core(), bc.kubeClient.Core(), build.Namespace, serviceAccount)
	if err != nil {
		return nil, fmt.Errorf("Error getting push/pull secrets for service account %s/%s: %v", build.Namespace, serviceAccount, err)
	}
	pushSecret := buildutil.FindDockerSecretAsReference(builderSecrets, imagename)
	if pushSecret == nil {
		glog.V(4).Infof("No secrets found for pushing or pulling image named %s for build %s/%s", imagename, build.Namespace, build.Name)
	}
	return pushSecret, nil
}

// resourceName creates a string that can be used to uniquely key the provided resource.
func resourceName(namespace, name string) string {
	return namespace + "/" + name
}

var (
	// errInvalidImageReferences is a marker error for when a build contains invalid object
	// reference names.
	errInvalidImageReferences = fmt.Errorf("one or more image references were invalid")
	// errNoIntegratedRegistry is a marker error for when the output image points to a registry
	// that cannot be resolved.
	errNoIntegratedRegistry = fmt.Errorf("the integrated registry is not configured")
)

// unresolvedImageStreamReferences finds all image stream references in the provided
// mutator that need to be resolved prior to the resource being accepted and returns
// them as an array of "namespace/name" strings. If any references are invalid, an error
// is returned.
func unresolvedImageStreamReferences(m meta.ImageReferenceMutator, defaultNamespace string) ([]string, error) {
	var streams []string
	fn := func(ref *kapi.ObjectReference) error {
		switch ref.Kind {
		case "ImageStreamImage":
			namespace := ref.Namespace
			if len(namespace) == 0 {
				namespace = defaultNamespace
			}
			name, _, ok := imageapi.SplitImageStreamImage(ref.Name)
			if !ok {
				return errInvalidImageReferences
			}
			streams = append(streams, resourceName(namespace, name))
		case "ImageStreamTag":
			namespace := ref.Namespace
			if len(namespace) == 0 {
				namespace = defaultNamespace
			}
			name, _, ok := imageapi.SplitImageStreamTag(ref.Name)
			if !ok {
				return errInvalidImageReferences
			}
			streams = append(streams, resourceName(namespace, name))
		}
		return nil
	}
	errs := m.Mutate(fn)
	if len(errs) > 0 {
		return nil, errInvalidImageReferences
	}
	return streams, nil
}

// resolveImageStreamLocation transforms the provided reference into a string pointing to the integrated registry,
// or returns an error.
func resolveImageStreamLocation(ref *kapi.ObjectReference, lister imagelister.ImageStreamLister, defaultNamespace string) (string, error) {
	namespace := ref.Namespace
	if len(namespace) == 0 {
		namespace = defaultNamespace
	}

	var (
		name string
		tag  string
	)
	switch ref.Kind {
	case "ImageStreamImage":
		var ok bool
		name, _, ok = imageapi.SplitImageStreamImage(ref.Name)
		if !ok {
			return "", errInvalidImageReferences
		}
		// for backwards compatibility, image stream images will be resolved to the :latest tag
		tag = imageapi.DefaultImageTag
	case "ImageStreamTag":
		var ok bool
		name, tag, ok = imageapi.SplitImageStreamTag(ref.Name)
		if !ok {
			return "", errInvalidImageReferences
		}
	case "ImageStream":
		name = ref.Name
	}

	stream, err := lister.ImageStreams(namespace).Get(name)
	if err != nil {
		if errors.IsNotFound(err) {
			return "", err
		}
		return "", fmt.Errorf("the referenced output image stream %s/%s could not be found: %v", namespace, name, err)
	}

	// TODO: this check will not work if the admin installs the registry without restarting the controller, because
	// only a relist from the API server will correct the empty value here (no watch events are sent)
	if len(stream.Status.DockerImageRepository) == 0 {
		return "", errNoIntegratedRegistry
	}

	repo, err := imageapi.ParseDockerImageReference(stream.Status.DockerImageRepository)
	if err != nil {
		return "", fmt.Errorf("the referenced output image stream does not represent a valid reference name: %v", err)
	}
	repo.ID = ""
	repo.Tag = tag
	return repo.Exact(), nil
}

func resolveImageStreamImage(ref *kapi.ObjectReference, lister imagelister.ImageStreamLister, defaultNamespace string) (*kapi.ObjectReference, error) {
	namespace := ref.Namespace
	if len(namespace) == 0 {
		namespace = defaultNamespace
	}
	name, imageID, ok := imageapi.SplitImageStreamImage(ref.Name)
	if !ok {
		return nil, errInvalidImageReferences
	}
	stream, err := lister.ImageStreams(namespace).Get(name)
	if err != nil {
		if errors.IsNotFound(err) {
			return nil, err
		}
		return nil, fmt.Errorf("the referenced image stream %s/%s could not be found: %v", namespace, name, err)
	}
	event, err := imageapi.ResolveImageID(stream, imageID)
	if err != nil {
		return nil, err
	}
	if len(event.DockerImageReference) == 0 {
		return nil, fmt.Errorf("the referenced image stream image %s/%s does not have a pull spec", namespace, ref.Name)
	}
	return &kapi.ObjectReference{Kind: "DockerImage", Name: event.DockerImageReference}, nil
}

func resolveImageStreamTag(ref *kapi.ObjectReference, lister imagelister.ImageStreamLister, defaultNamespace string) (*kapi.ObjectReference, error) {
	namespace := ref.Namespace
	if len(namespace) == 0 {
		namespace = defaultNamespace
	}
	name, tag, ok := imageapi.SplitImageStreamTag(ref.Name)
	if !ok {
		return nil, errInvalidImageReferences
	}
	stream, err := lister.ImageStreams(namespace).Get(name)
	if err != nil {
		if errors.IsNotFound(err) {
			return nil, err
		}
		return nil, fmt.Errorf("the referenced image stream %s/%s could not be found: %v", namespace, name, err)
	}
	if newRef, ok := imageapi.ResolveLatestTaggedImage(stream, tag); ok {
		return &kapi.ObjectReference{Kind: "DockerImage", Name: newRef}, nil
	}
	return nil, fmt.Errorf("the referenced image stream tag %s/%s does not exist", namespace, ref.Name)
}

// resolveOutputDockerImageReference updates the output spec to a docker image reference.
func (bc *BuildController) resolveOutputDockerImageReference(build *buildapi.Build) error {
	ref := build.Spec.Output.To
	if ref == nil || ref.Name == "" {
		return nil
	}

	switch ref.Kind {
	case "ImageStream", "ImageStreamTag":
		newRef, err := resolveImageStreamLocation(ref, bc.imageStreamStore, build.Namespace)
		if err != nil {
			return err
		}
		*ref = kapi.ObjectReference{Kind: "DockerImage", Name: newRef}
		return nil
	default:
		return nil
	}
}

// resolveImageReferences resolves references to Docker images computed from the build.Spec. It will update
// the output spec as well if it has not already been updated.
func (bc *BuildController) resolveImageReferences(build *buildapi.Build, update *buildUpdate) error {
	m := meta.NewBuildMutator(build)

	// get a list of all unresolved references to add to the cache
	streams, err := unresolvedImageStreamReferences(m, build.Namespace)
	if err != nil {
		return err
	}
	if len(streams) == 0 {
		glog.V(5).Infof("Build %s contains no unresolved image references", build.Name)
		return nil
	}

	// build references are level driven, so we queue here to ensure we get notified if
	// we are racing against updates in the image stream store
	buildKey := resourceName(build.Namespace, build.Name)
	bc.imageStreamQueue.Add(buildKey, streams)

	// resolve the output image reference
	if err := bc.resolveOutputDockerImageReference(build); err != nil {
		// If we cannot resolve the output reference, the output image stream
		// may not yet exist. The build should remain in the new state and show the
		// reason that it is still in the new state.
		update.setReason(buildapi.StatusReasonInvalidOutputReference)
		update.setMessage(buildapi.StatusMessageInvalidOutputRef)
		if err == errNoIntegratedRegistry {
			e := fmt.Errorf("an image stream cannot be used as build output because the integrated Docker registry is not configured")
			bc.recorder.Eventf(build, kapi.EventTypeWarning, "InvalidOutput", "Error starting build: %v", e)
		}
		return err
	}
	// resolve the remaining references
	errs := m.Mutate(func(ref *kapi.ObjectReference) error {
		switch ref.Kind {
		case "ImageStreamImage":
			newRef, err := resolveImageStreamImage(ref, bc.imageStreamStore, build.Namespace)
			if err != nil {
				return err
			}
			*ref = *newRef
		case "ImageStreamTag":
			newRef, err := resolveImageStreamTag(ref, bc.imageStreamStore, build.Namespace)
			if err != nil {
				return err
			}
			*ref = *newRef
		}
		return nil
	})

	if len(errs) > 0 {
		update.setReason(buildapi.StatusReasonInvalidImageReference)
		update.setMessage(buildapi.StatusMessageInvalidImageRef)
		return errs.ToAggregate()
	}
	// we have resolved all images, and will not need any further notifications
	bc.imageStreamQueue.Remove(buildKey, streams)
	return nil
}

// createBuildPod creates a new pod to run a build
func (bc *BuildController) createBuildPod(build *buildapi.Build) (*buildUpdate, error) {
	update := &buildUpdate{}

	// image reference resolution requires a copy of the build
	var err error
	build, err = buildutil.BuildDeepCopy(build)
	if err != nil {
		return nil, fmt.Errorf("unable to copy build %s: %v", buildDesc(build), err)
	}

	// Resolve all Docker image references to valid values.
	if err := bc.resolveImageReferences(build, update); err != nil {
		// if we're waiting for an image stream to exist, we will get an update via the
		// trigger, and thus don't need to be requeued.
		if hasError(err, errors.IsNotFound, field.NewErrorTypeMatcher(field.ErrorTypeNotFound)) {
			return update, nil
		}
		return update, err
	}

	// Set the pushSecret that will be needed by the build to push the image to the registry
	// at the end of the build.
	pushSecret := build.Spec.Output.PushSecret
	// Only look up a push secret if the user hasn't explicitly provided one.
	if build.Spec.Output.PushSecret == nil && build.Spec.Output.To != nil && len(build.Spec.Output.To.Name) > 0 {
		var err error
		pushSecret, err = bc.resolveImageSecretAsReference(build, build.Spec.Output.To.Name)
		if err != nil {
			update.setReason(buildapi.StatusReasonCannotRetrieveServiceAccount)
			update.setMessage(buildapi.StatusMessageCannotRetrieveServiceAccount)
			return update, err
		}
	}
	build.Spec.Output.PushSecret = pushSecret

	// Set the pullSecret that will be needed by the build to pull the base/builder image.
	var pullSecret *kapi.LocalObjectReference
	var imageName string
	switch {
	case build.Spec.Strategy.SourceStrategy != nil:
		pullSecret = build.Spec.Strategy.SourceStrategy.PullSecret
		imageName = build.Spec.Strategy.SourceStrategy.From.Name
	case build.Spec.Strategy.DockerStrategy != nil:
		pullSecret = build.Spec.Strategy.DockerStrategy.PullSecret
		if build.Spec.Strategy.DockerStrategy.From != nil {
			imageName = build.Spec.Strategy.DockerStrategy.From.Name
		}
	case build.Spec.Strategy.CustomStrategy != nil:
		pullSecret = build.Spec.Strategy.CustomStrategy.PullSecret
		imageName = build.Spec.Strategy.CustomStrategy.From.Name
	}
	// Only look up a pull secret if the user hasn't explicitly provided one and
	// we have a base/builder image (Docker builds may not have one).
	if pullSecret == nil && len(imageName) != 0 {
		var err error
		pullSecret, err = bc.resolveImageSecretAsReference(build, imageName)
		if err != nil {
			update.setReason(buildapi.StatusReasonCannotRetrieveServiceAccount)
			update.setMessage(buildapi.StatusMessageCannotRetrieveServiceAccount)
			return update, err
		}
		if pullSecret != nil {
			switch {
			case build.Spec.Strategy.SourceStrategy != nil:
				build.Spec.Strategy.SourceStrategy.PullSecret = pullSecret
			case build.Spec.Strategy.DockerStrategy != nil:
				build.Spec.Strategy.DockerStrategy.PullSecret = pullSecret
			case build.Spec.Strategy.CustomStrategy != nil:
				build.Spec.Strategy.CustomStrategy.PullSecret = pullSecret
			}
		}
	}

	// look up the secrets needed to pull any source input images.
	for i, s := range build.Spec.Source.Images {
		if s.PullSecret != nil {
			continue
		}
		imageInputPullSecret, err := bc.resolveImageSecretAsReference(build, s.From.Name)
		if err != nil {
			update.setReason(buildapi.StatusReasonCannotRetrieveServiceAccount)
			update.setMessage(buildapi.StatusMessageCannotRetrieveServiceAccount)
			return update, err
		}
		build.Spec.Source.Images[i].PullSecret = imageInputPullSecret
	}

	if build.Spec.Strategy.CustomStrategy != nil {
		buildgenerator.UpdateCustomImageEnv(build.Spec.Strategy.CustomStrategy, build.Spec.Strategy.CustomStrategy.From.Name)
	}

	// Create the build pod spec
	buildPod, err := bc.createPodSpec(build)
	if err != nil {
		switch err.(type) {
		case common.ErrEnvVarResolver:
			update = transitionToPhase(buildapi.BuildPhaseError, buildapi.StatusReasonUnresolvableEnvironmentVariable, fmt.Sprintf("%v, %v", buildapi.StatusMessageUnresolvableEnvironmentVariable, err.Error()))
		default:
			update.setReason(buildapi.StatusReasonCannotCreateBuildPodSpec)
			update.setMessage(buildapi.StatusMessageCannotCreateBuildPodSpec)

		}
		// If an error occurred when creating the pod spec, it likely means
		// that the build is something we don't understand. For example, it could
		// have a strategy that we don't recognize. It will remain in New state
		// and be updated with the reason that it is still in New

		// The error will be logged, but will not be returned to the caller
		// to be retried. The reason is that there's really no external factor
		// that could cause the pod creation to fail; therefore no reason
		// to immediately retry processing the build.
		//
		// A scenario where this would happen is that we've introduced a
		// new build strategy in the master, but the old version of the controller
		// is still running. We don't want the old controller to move the
		// build to the error phase and we don't want it to keep actively retrying.
		utilruntime.HandleError(err)
		return update, nil
	}

	glog.V(4).Infof("Pod %s/%s for build %s is about to be created", build.Namespace, buildPod.Name, buildDesc(build))
	if _, err := bc.podClient.Pods(build.Namespace).Create(buildPod); err != nil {
		if errors.IsAlreadyExists(err) {
			bc.recorder.Eventf(build, kapi.EventTypeWarning, "FailedCreate", "Pod already exists: %s/%s", buildPod.Namespace, buildPod.Name)
			glog.V(4).Infof("Build pod %s/%s for build %s already exists", build.Namespace, buildPod.Name, buildDesc(build))

			// If the existing pod was created before this build, switch to the Error state.
			existingPod, err := bc.podClient.Pods(build.Namespace).Get(buildPod.Name, metav1.GetOptions{})
			if err == nil && existingPod.CreationTimestamp.Before(build.CreationTimestamp) {
				update = transitionToPhase(buildapi.BuildPhaseError, buildapi.StatusReasonBuildPodExists, buildapi.StatusMessageBuildPodExists)
				return update, nil
			}
			return nil, nil
		}
		// Log an event if the pod is not created (most likely due to quota denial).
		bc.recorder.Eventf(build, kapi.EventTypeWarning, "FailedCreate", "Error creating: %v", err)
		update.setReason(buildapi.StatusReasonCannotCreateBuildPod)
		update.setMessage(buildapi.StatusMessageCannotCreateBuildPod)
		return update, fmt.Errorf("failed to create build pod: %v", err)
	}
	glog.V(4).Infof("Created pod %s/%s for build %s", build.Namespace, buildPod.Name, buildDesc(build))
	update = transitionToPhase(buildapi.BuildPhasePending, "", "")

	if pushSecret != nil {
		update.setPushSecret(*pushSecret)
	}

	update.setPodNameAnnotation(buildPod.Name)
	if build.Spec.Output.To != nil {
		update.setOutputRef(build.Spec.Output.To.Name)
	}
	return update, nil
}

// handleActiveBuild handles a build in either pending or running state
func (bc *BuildController) handleActiveBuild(build *buildapi.Build, pod *v1.Pod) (*buildUpdate, error) {
	if pod == nil {
		pod = bc.findMissingPod(build)
		if pod == nil {
			glog.V(4).Infof("Failed to find the build pod for build %s. Moving it to Error state", buildDesc(build))
			return transitionToPhase(buildapi.BuildPhaseError, buildapi.StatusReasonBuildPodDeleted, buildapi.StatusMessageBuildPodDeleted), nil
		}
	}

	podPhase := pod.Status.Phase
	var update *buildUpdate
	// Pods don't report running until initcontainers are done, but from a build's perspective
	// the pod is running as soon as the first init container has run.
	if build.Status.Phase == buildapi.BuildPhasePending || build.Status.Phase == buildapi.BuildPhaseNew {
		for _, initContainer := range pod.Status.InitContainerStatuses {
			if initContainer.Name == strategy.GitCloneContainer && initContainer.State.Running != nil {
				podPhase = v1.PodRunning
			}
		}
	}
	switch podPhase {
	case v1.PodPending:
		if build.Status.Phase != buildapi.BuildPhasePending {
			update = transitionToPhase(buildapi.BuildPhasePending, "", "")
		}
		if secret := build.Spec.Output.PushSecret; secret != nil && build.Status.Reason != buildapi.StatusReasonMissingPushSecret {
			if _, err := bc.secretStore.Secrets(build.Namespace).Get(secret.Name); err != nil && errors.IsNotFound(err) {
				glog.V(4).Infof("Setting reason for pending build to %q due to missing secret for %s", build.Status.Reason, buildDesc(build))
				update = transitionToPhase(buildapi.BuildPhasePending, buildapi.StatusReasonMissingPushSecret, buildapi.StatusMessageMissingPushSecret)
			}
		}
	case v1.PodRunning:
		if build.Status.Phase != buildapi.BuildPhaseRunning {
			update = transitionToPhase(buildapi.BuildPhaseRunning, "", "")
			if pod.Status.StartTime != nil {
				update.setStartTime(*pod.Status.StartTime)
			}
		}
	case v1.PodSucceeded:
		if build.Status.Phase != buildapi.BuildPhaseComplete {
			update = transitionToPhase(buildapi.BuildPhaseComplete, "", "")
		}
		if len(pod.Status.ContainerStatuses) == 0 {
			// no containers in the pod means something went terribly wrong, so the build
			// should be set to an error state
			glog.V(2).Infof("Setting build %s to error state because its pod has no containers", buildDesc(build))
			update = transitionToPhase(buildapi.BuildPhaseError, buildapi.StatusReasonNoBuildContainerStatus, buildapi.StatusMessageNoBuildContainerStatus)
		} else {
			for _, info := range pod.Status.ContainerStatuses {
				if info.State.Terminated != nil && info.State.Terminated.ExitCode != 0 {
					glog.V(2).Infof("Setting build %s to error state because a container in its pod has non-zero exit code", buildDesc(build))
					update = transitionToPhase(buildapi.BuildPhaseError, buildapi.StatusReasonFailedContainer, buildapi.StatusMessageFailedContainer)
					break
				}
			}
		}
	case v1.PodFailed:
		if build.Status.Phase != buildapi.BuildPhaseFailed {
			// If a DeletionTimestamp has been set, it means that the pod will
			// soon be deleted. The build should be transitioned to the Error phase.
			if pod.DeletionTimestamp != nil {
				update = transitionToPhase(buildapi.BuildPhaseError, buildapi.StatusReasonBuildPodDeleted, buildapi.StatusMessageBuildPodDeleted)
			} else {
				update = transitionToPhase(buildapi.BuildPhaseFailed, buildapi.StatusReasonGenericBuildFailed, buildapi.StatusMessageGenericBuildFailed)
			}
		}
	}
	return update, nil
}

// handleCompletedBuild will only be called on builds that are already in a terminal phase.  It is used to setup the
// completion timestamp and failure logsnippet as needed.
func (bc *BuildController) handleCompletedBuild(build *buildapi.Build, pod *v1.Pod) (*buildUpdate, error) {

	update := &buildUpdate{}
	setBuildCompletionData(build, pod, update)

	return update, nil
}

// updateBuild is the single place where any update to a build is done in the build controller.
// It will check that the update is valid, peform any necessary processing such as calling HandleBuildCompletion,
// and apply the buildUpdate object as a patch.
func (bc *BuildController) updateBuild(build *buildapi.Build, update *buildUpdate, pod *v1.Pod) error {

	stateTransition := false
	// Check whether we are transitioning to a different build phase
	if update.phase != nil && (*update.phase) != build.Status.Phase {
		stateTransition = true
	} else if build.Status.Phase == buildapi.BuildPhaseFailed && update.completionTime != nil {
		// Treat a failed->failed update as a state transition when the completionTime is getting
		// updated. This will cause an event to be emitted and completion processing to trigger.
		// We get into this state when the pod updates the phase through the build/details subresource.
		// The phase, reason, and message are set, but no event has been emitted about the failure,
		// and the policy has not been given a chance to start the next build if one is waiting to
		// start.
		update.setPhase(buildapi.BuildPhaseFailed)
		stateTransition = true
	}

	if stateTransition {
		// Make sure that the transition is valid
		if !isValidTransition(build.Status.Phase, *update.phase) {
			return fmt.Errorf("invalid phase transition %s -> %s", buildDesc(build), *update.phase)
		}

		// Log that we are updating build status
		reasonText := ""
		if update.reason != nil && *update.reason != "" {
			reasonText = fmt.Sprintf(" ( %s )", *update.reason)
		}

		// Update build completion timestamp if transitioning to a terminal phase
		if buildutil.IsTerminalPhase(*update.phase) {
			setBuildCompletionData(build, pod, update)
		}
		glog.V(4).Infof("Updating build %s -> %s%s", buildDesc(build), *update.phase, reasonText)
	}

	// Ensure that a pod name annotation has been set on the build if a pod is available
	if update.podNameAnnotation == nil && !common.HasBuildPodNameAnnotation(build) && pod != nil {
		update.setPodNameAnnotation(pod.Name)
	}

	patchedBuild, err := bc.patchBuild(build, update)
	if err != nil {
		return err
	}

	// Emit events and handle build completion if transitioned to a terminal phase
	if stateTransition {
		switch *update.phase {
		case buildapi.BuildPhaseRunning:
			bc.recorder.Eventf(patchedBuild, kapi.EventTypeNormal, buildapi.BuildStartedEventReason, fmt.Sprintf(buildapi.BuildStartedEventMessage, patchedBuild.Namespace, patchedBuild.Name))
		case buildapi.BuildPhaseCancelled:
			bc.recorder.Eventf(patchedBuild, kapi.EventTypeNormal, buildapi.BuildCancelledEventReason, fmt.Sprintf(buildapi.BuildCancelledEventMessage, patchedBuild.Namespace, patchedBuild.Name))
		case buildapi.BuildPhaseComplete:
			bc.recorder.Eventf(patchedBuild, kapi.EventTypeNormal, buildapi.BuildCompletedEventReason, fmt.Sprintf(buildapi.BuildCompletedEventMessage, patchedBuild.Namespace, patchedBuild.Name))
		case buildapi.BuildPhaseError,
			buildapi.BuildPhaseFailed:
			bc.recorder.Eventf(patchedBuild, kapi.EventTypeNormal, buildapi.BuildFailedEventReason, fmt.Sprintf(buildapi.BuildFailedEventMessage, patchedBuild.Namespace, patchedBuild.Name))
		}
		if buildutil.IsTerminalPhase(*update.phase) {
			bc.handleBuildCompletion(patchedBuild)
		}
	}
	return nil
}

func (bc *BuildController) handleBuildCompletion(build *buildapi.Build) {
	bcName := buildutil.ConfigNameForBuild(build)
	bc.enqueueBuildConfig(build.Namespace, bcName)
	if err := common.HandleBuildPruning(bcName, build.Namespace, bc.buildLister, bc.buildConfigGetter, bc.buildDeleter); err != nil {
		utilruntime.HandleError(fmt.Errorf("failed to prune old builds %s/%s: %v", build.Namespace, build.Name, err))
	}
}

func (bc *BuildController) enqueueBuildConfig(ns, name string) {
	key := resourceName(ns, name)
	bc.buildConfigQueue.Add(key)
}

func (bc *BuildController) handleBuildConfig(bcNamespace string, bcName string) error {
	glog.V(4).Infof("Handing build config %s/%s", bcNamespace, bcName)
	nextBuilds, hasRunningBuilds, err := policy.GetNextConfigBuild(bc.buildLister, bcNamespace, bcName)
	if err != nil {
		glog.V(2).Infof("Error getting next builds for %s/%s: %v", bcNamespace, bcName, err)
		return err
	}
	glog.V(5).Infof("Build config %s/%s: has %d next builds, is running builds: %v", bcNamespace, bcName, len(nextBuilds), hasRunningBuilds)
	if len(nextBuilds) == 0 && hasRunningBuilds {
		glog.V(4).Infof("Build config %s/%s has running builds, will retry", bcNamespace, bcName)
		return fmt.Errorf("build config %s/%s has running builds and cannot run more builds", bcNamespace, bcName)
	}

	// Enqueue any builds to build next
	for _, build := range nextBuilds {
		glog.V(5).Infof("Queueing next build for build config %s/%s: %s", bcNamespace, bcName, build.Name)
		bc.enqueueBuild(build)
	}
	return nil
}

// patchBuild generates a patch for the given build and buildUpdate
// and applies that patch using the REST client
func (bc *BuildController) patchBuild(build *buildapi.Build, update *buildUpdate) (*buildapi.Build, error) {
	// Create a patch using the buildUpdate object
	updatedBuild, err := buildutil.BuildDeepCopy(build)
	if err != nil {
		return nil, fmt.Errorf("cannot create a deep copy of build %s: %v", buildDesc(build), err)
	}
	update.apply(updatedBuild)

	patch, err := validation.CreateBuildPatch(build, updatedBuild)
	if err != nil {
		return nil, fmt.Errorf("failed to create a build patch: %v", err)
	}

	glog.V(5).Infof("Patching build %s with %v", buildDesc(build), update)
	return bc.buildPatcher.Patch(build.Namespace, build.Name, patch)
}

// findMissingPod uses the REST client directly to determine if a pod exists or not.
// It is called when a corresponding pod for a build is not found in the cache.
func (bc *BuildController) findMissingPod(build *buildapi.Build) *v1.Pod {
	// Make one last attempt to fetch the pod using the REST client
	pod, err := bc.podClient.Pods(build.Namespace).Get(buildapi.GetBuildPodName(build), metav1.GetOptions{})
	if err == nil {
		glog.V(2).Infof("Found missing pod for build %s by using direct client.", buildDesc(build))
		return pod
	}
	return nil
}

// getBuildByKey looks up a build by key in the buildInformer cache
func (bc *BuildController) getBuildByKey(key string) (*buildapi.Build, error) {
	obj, exists, err := bc.buildInformer.GetIndexer().GetByKey(key)
	if err != nil {
		glog.V(2).Infof("Unable to retrieve build %q from store: %v", key, err)
		return nil, err
	}
	if !exists {
		glog.V(2).Infof("Build %q has been deleted", key)
		return nil, nil
	}

	return obj.(*buildapi.Build), nil
}

// podUpdated gets called by the pod informer event handler whenever a pod
// is updated or there is a relist of pods
func (bc *BuildController) podUpdated(old, cur interface{}) {
	// A periodic relist will send update events for all known pods.
	curPod := cur.(*v1.Pod)
	oldPod := old.(*v1.Pod)
	// The old and new ResourceVersion will be the same in a relist of pods.
	// Here we ignore pod relists because we already listen to build relists.
	if curPod.ResourceVersion == oldPod.ResourceVersion {
		return
	}
	if isBuildPod(curPod) {
		bc.enqueueBuildForPod(curPod)
	}
}

// podDeleted gets called by the pod informer event handler whenever a pod
// is deleted
func (bc *BuildController) podDeleted(obj interface{}) {
	pod, ok := obj.(*v1.Pod)
	if !ok {
		tombstone, ok := obj.(cache.DeletedFinalStateUnknown)
		if !ok {
			utilruntime.HandleError(fmt.Errorf("couldn't get object from tombstone: %+v", obj))
			return
		}
		pod, ok = tombstone.Obj.(*v1.Pod)
		if !ok {
			utilruntime.HandleError(fmt.Errorf("tombstone contained object that is not a pod: %+v", obj))
			return
		}
	}
	if isBuildPod(pod) {
		bc.enqueueBuildForPod(pod)
	}
}

// buildAdded is called by the build informer event handler whenever a build
// is created
func (bc *BuildController) buildAdded(obj interface{}) {
	build := obj.(*buildapi.Build)
	bc.enqueueBuild(build)
}

// buildUpdated is called by the build informer event handler whenever a build
// is updated or there is a relist of builds
func (bc *BuildController) buildUpdated(old, cur interface{}) {
	build := cur.(*buildapi.Build)
	bc.enqueueBuild(build)
}

// enqueueBuild adds the given build to the buildQueue.
func (bc *BuildController) enqueueBuild(build *buildapi.Build) {
	key := resourceName(build.Namespace, build.Name)
	bc.buildQueue.Add(key)
}

// enqueueBuildForPod adds the build corresponding to the given pod to the controller
// buildQueue. If a build is not found for the pod, then an error is logged.
func (bc *BuildController) enqueueBuildForPod(pod *v1.Pod) {
	bc.buildQueue.Add(resourceName(pod.Namespace, buildutil.GetBuildName(pod)))
}

// imageStreamAdded queues any builds that have registered themselves for this image stream.
// Because builds are level driven when resolving images, we are not concerned with duplicate
// build events.
func (bc *BuildController) imageStreamAdded(obj interface{}) {
	stream := obj.(*imageapi.ImageStream)
	for _, buildKey := range bc.imageStreamQueue.Pop(resourceName(stream.Namespace, stream.Name)) {
		bc.buildQueue.Add(buildKey)
	}
}

// imageStreamUpdated queues any builds that have registered themselves for the image stream.
func (bc *BuildController) imageStreamUpdated(old, cur interface{}) {
	bc.imageStreamAdded(cur)
}

// handleBuildError is called by the main work loop to check the return of calling handleBuild.
// If an error occurred, then the key is re-added to the buildQueue unless it has been retried too many
// times.
func (bc *BuildController) handleBuildError(err error, key interface{}) {
	if err == nil {
		bc.buildQueue.Forget(key)
		return
	}

	if strategy.IsFatal(err) {
		glog.V(2).Infof("Will not retry fatal error for key %v: %v", key, err)
		bc.buildQueue.Forget(key)
		return
	}

	if bc.buildQueue.NumRequeues(key) < maxRetries {
		glog.V(4).Infof("Retrying key %v: %v", key, err)
		bc.buildQueue.AddRateLimited(key)
		return
	}

	glog.V(2).Infof("Giving up retrying %v: %v", key, err)
	bc.buildQueue.Forget(key)
}

// handleBuildConfigError is called by the buildConfig work loop to check the return of calling handleBuildConfig.
// If an error occurred, then the key is re-added to the buildConfigQueue unless it has been retried too many
// times.
func (bc *BuildController) handleBuildConfigError(err error, key interface{}) {
	if err == nil {
		bc.buildConfigQueue.Forget(key)
		return
	}

	if bc.buildConfigQueue.NumRequeues(key) < maxRetries {
		glog.V(4).Infof("Retrying key %v: %v", key, err)
		bc.buildConfigQueue.AddRateLimited(key)
		return
	}

	glog.V(2).Infof("Giving up retrying %v: %v", key, err)
	bc.buildConfigQueue.Forget(key)
}

// isBuildPod returns true if the given pod is a build pod
func isBuildPod(pod *v1.Pod) bool {
	return len(buildutil.GetBuildName(pod)) > 0
}

// buildDesc is a utility to format the namespace/name and phase of a build
// for errors and logging
func buildDesc(build *buildapi.Build) string {
	return fmt.Sprintf("%s/%s (%s)", build.Namespace, build.Name, build.Status.Phase)
}

// transitionToPhase returns a buildUpdate object to transition a build to a new
// phase with the given reason and message
func transitionToPhase(phase buildapi.BuildPhase, reason buildapi.StatusReason, message string) *buildUpdate {
	update := &buildUpdate{}
	update.setPhase(phase)
	update.setReason(reason)
	update.setMessage(message)
	return update
}

// isValidTransition returns true if the given phase transition is valid
func isValidTransition(from, to buildapi.BuildPhase) bool {
	if from == to {
		return true
	}

	switch {
	case buildutil.IsTerminalPhase(from):
		return false
	case from == buildapi.BuildPhasePending:
		switch to {
		case buildapi.BuildPhaseNew:
			return false
		}
	case from == buildapi.BuildPhaseRunning:
		switch to {
		case buildapi.BuildPhaseNew,
			buildapi.BuildPhasePending:
			return false
		}
	}

	return true
}

// setBuildCompletionData sets the build completion time and duration as well as the start time
// if not already set on the given buildUpdate object.  It also sets the log tail data
// if applicable.
func setBuildCompletionData(build *buildapi.Build, pod *v1.Pod, update *buildUpdate) {
	now := metav1.Now()

	startTime := build.Status.StartTimestamp
	if startTime == nil {
		if pod != nil {
			startTime = pod.Status.StartTime
		}

		if startTime == nil {
			startTime = &now
		}
		update.setStartTime(*startTime)
	}
	if build.Status.CompletionTimestamp == nil {
		update.setCompletionTime(now)
		update.setDuration(now.Rfc3339Copy().Time.Sub(startTime.Rfc3339Copy().Time))
	}

	if build.Status.Phase == buildapi.BuildPhaseFailed && len(build.Status.LogSnippet) == 0 &&
		pod != nil && len(pod.Status.ContainerStatuses) != 0 && pod.Status.ContainerStatuses[0].State.Terminated != nil {
		msg := pod.Status.ContainerStatuses[0].State.Terminated.Message
		if len(msg) != 0 {
			parts := strings.Split(strings.TrimRight(msg, "\n"), "\n")

			excerptLength := maxExcerptLength
			if len(parts) < maxExcerptLength {
				excerptLength = len(parts)
			}
			excerpt := parts[len(parts)-excerptLength:]
			for i, line := range excerpt {
				if len(line) > 120 {
					excerpt[i] = line[:58] + "..." + line[len(line)-59:]
				}
			}
			msg = strings.Join(excerpt, "\n")
			update.setLogSnippet(msg)
		}
	}

}

// hasError returns true if any error (aggregate or no) matches any of the
// provided functions.
func hasError(err error, fns ...utilerrors.Matcher) bool {
	if err == nil {
		return false
	}
	if agg, ok := err.(utilerrors.Aggregate); ok {
		for _, err := range agg.Errors() {
			if hasError(err, fns...) {
				return true
			}
		}
		return false
	}
	for _, fn := range fns {
		if fn(err) {
			return true
		}
	}
	return false
}