Added Selector Generation to Job.

Added selector generation to Job's
strategy.Validate, right before validation.
Can't do in defaulting since UID is not known.

Added a validation to Job to ensure that the generated
labels and selector are correct when generation was requested.
This happens right after generation, but validation is in a better
place to return an error.

Adds "manualSelector" field to batch/v1 Job to control selector generation.
Adds same field to extensions/__internal.  Conversion between those two
is automatic.

Adds "autoSelector" field to extensions/v1beta1 Job.  Used for storing batch/v1 Jobs
    - Default for v1 is to do generation.
    - Default for v1beta1 is to not do it.
    - In both cases, unset == false == do the default thing.

Release notes:
Added batch/v1 group, which contains just Job, and which is the next
version of extensions/v1beta1 Job.

The changes from the previous version are:
- Users no longer need to ensure labels on their pod template are unique to the enclosing
  job (but may add labels as needed for categorization).
- In v1beta1, job.spec.selector was defaulted from pod labels, with the user responsible for uniqueness.
  In v1, a unique label is generated and added to the pod template, and used as the selector (other
  labels added by user stay on pod template, but need not be used by selector).
- a new field called "manualSelector" field exists to control whether the new behavior is used,
  versus a more error-prone but more flexible "manual" (not generated) seletor.  Most users
  will not need to use this field and should leave it unset.

Users who are creating extensions.Job go objects and then posting them using the go client
will see a change in the default behavior.  They need to either stop providing a selector (relying on
selector generation) or else specify "spec.manualSelector" until they are ready to do the former.

examples/examples_test.go

@@ -32,7 +32,9 @@ import (
 	"k8s.io/kubernetes/pkg/apis/extensions"
 	expvalidation "k8s.io/kubernetes/pkg/apis/extensions/validation"
 	"k8s.io/kubernetes/pkg/capabilities"
+	"k8s.io/kubernetes/pkg/registry/job"
 	"k8s.io/kubernetes/pkg/runtime"
+	"k8s.io/kubernetes/pkg/types"
 	"k8s.io/kubernetes/pkg/util/validation/field"
 	"k8s.io/kubernetes/pkg/util/yaml"
 	schedulerapi "k8s.io/kubernetes/plugin/pkg/scheduler/api"
@@ -111,7 +113,10 @@ func validateObject(obj runtime.Object) (errors field.ErrorList) {
 		if t.Namespace == "" {
 			t.Namespace = api.NamespaceDefault
 		}
-		errors = expvalidation.ValidateJob(t)
+		// Job needs generateSelector called before validation, and job.Validate does this.
+		// See: https://github.com/kubernetes/kubernetes/issues/20951#issuecomment-187787040
+		t.ObjectMeta.UID = types.UID("fakeuid")
+		errors = job.Strategy.Validate(nil, t)
 	case *extensions.Ingress:
 		if t.Namespace == "" {
 			t.Namespace = api.NamespaceDefault

pkg/api/testing/fuzzer.go

@@ -162,6 +162,11 @@ func FuzzerFor(t *testing.T, version unversioned.GroupVersion, src rand.Source)
 			parallelism := int(c.Rand.Int31())
 			j.Completions = &completions
 			j.Parallelism = &parallelism
+			if c.Rand.Int31()%2 == 0 {
+				j.ManualSelector = newBool(true)
+			} else {
+				j.ManualSelector = nil
+			}
 		},
 		func(j *api.List, c fuzz.Continue) {
 			c.FuzzNoCustom(j) // fuzz self without calling this function again
@@ -411,3 +416,9 @@ func FuzzerFor(t *testing.T, version unversioned.GroupVersion, src rand.Source)
 	)
 	return f
 }
+
+func newBool(val bool) *bool {
+	p := new(bool)
+	*p = val
+	return p
+}

pkg/apis/batch/v1/defaults.go

@@ -23,18 +23,6 @@ import (
 func addDefaultingFuncs(scheme *runtime.Scheme) {
 	scheme.AddDefaultingFuncs(
 		func(obj *Job) {
-			labels := obj.Spec.Template.Labels
-			// TODO: support templates defined elsewhere when we support them in the API
-			if labels != nil {
-				if obj.Spec.Selector == nil {
-					obj.Spec.Selector = &LabelSelector{
-						MatchLabels: labels,
-					}
-				}
-				if len(obj.Labels) == 0 {
-					obj.Labels = labels
-				}
-			}
 			// For a non-parallel job, you can leave both `.spec.completions` and
 			// `.spec.parallelism` unset.  When both are unset, both are defaulted to 1.
 			if obj.Spec.Completions == nil && obj.Spec.Parallelism == nil {

pkg/apis/batch/v1/types.go

@@ -63,6 +63,7 @@ type JobSpec struct {
 	// pod signals the success of all pods, and allows parallelism to have any positive
 	// value.  Setting to 1 means that parallelism is limited to 1 and the success of that
 	// pod signals the success of the job.
+	// More info: http://releases.k8s.io/HEAD/docs/user-guide/jobs.md
 	Completions *int32 `json:"completions,omitempty"`
 
 	// Optional duration in seconds relative to the startTime that the job may be active
@@ -70,9 +71,22 @@ type JobSpec struct {
 	ActiveDeadlineSeconds *int64 `json:"activeDeadlineSeconds,omitempty"`
 
 	// Selector is a label query over pods that should match the pod count.
+	// Normally, the system sets this field for you.
 	// More info: http://releases.k8s.io/HEAD/docs/user-guide/labels.md#label-selectors
 	Selector *LabelSelector `json:"selector,omitempty"`
 
+	// ManualSelector controls generation of pod labels and pod selectors.
+	// Leave `manualSelector` unset unless you are certain what you are doing.
+	// When false or unset, the system pick labels unique to this job
+	// and appends those labels to the pod template.  When true,
+	// the user is responsible for picking unique labels and specifying
+	// the selector.  Failure to pick a unique label may cause this
+	// and other jobs to not function correctly.  However, You may see
+	// `manualSelector=true` in jobs that were created with the old `extensions/v1beta1`
+	// API.
+	// More info: http://releases.k8s.io/HEAD/docs/design/selector-generation.md
+	ManualSelector *bool `json:"manualSelector,omitempty"`
+
 	// Template is the object that describes the pod that will be created when
 	// executing a job.
 	// More info: http://releases.k8s.io/HEAD/docs/user-guide/jobs.md

pkg/apis/extensions/types.go

@@ -535,7 +535,10 @@ type JobSpec struct {
 	Parallelism *int `json:"parallelism,omitempty"`
 
 	// Completions specifies the desired number of successfully finished pods the
-	// job should be run with.  When unset, any pod exiting signals the job to complete.
+	// job should be run with.  Setting to nil means that the success of any
+	// pod signals the success of all pods, and allows parallelism to have any positive
+	// value.  Setting to 1 means that parallelism is limited to 1 and the success of that
+	// pod signals the success of the job.
 	Completions *int `json:"completions,omitempty"`
 
 	// Optional duration in seconds relative to the startTime that the job may be active
@@ -543,8 +546,20 @@ type JobSpec struct {
 	ActiveDeadlineSeconds *int64 `json:"activeDeadlineSeconds,omitempty"`
 
 	// Selector is a label query over pods that should match the pod count.
+	// Normally, the system sets this field for you.
 	Selector *unversioned.LabelSelector `json:"selector,omitempty"`
 
+	// ManualSelector controls generation of pod labels and pod selectors.
+	// Leave `manualSelector` unset unless you are certain what you are doing.
+	// When false or unset, the system pick labels unique to this job
+	// and appends those labels to the pod template.  When true,
+	// the user is responsible for picking unique labels and specifying
+	// the selector.  Failure to pick a unique label may cause this
+	// and other jobs to not function correctly.  However, You may see
+	// `manualSelector=true` in jobs that were created with the old `extensions/v1beta1`
+	// API.
+	ManualSelector *bool `json:"manualSelector,omitempty"`
+
 	// Template is the object that describes the pod that will be created when
 	// executing a job.
 	Template api.PodTemplateSpec `json:"template"`

pkg/apis/extensions/v1beta1/types.go

@@ -543,6 +543,7 @@ type JobSpec struct {
 	// pod signals the success of all pods, and allows parallelism to have any positive
 	// value.  Setting to 1 means that parallelism is limited to 1 and the success of that
 	// pod signals the success of the job.
+	// More info: http://releases.k8s.io/HEAD/docs/user-guide/jobs.md
 	Completions *int32 `json:"completions,omitempty"`
 
 	// Optional duration in seconds relative to the startTime that the job may be active
@@ -550,9 +551,17 @@ type JobSpec struct {
 	ActiveDeadlineSeconds *int64 `json:"activeDeadlineSeconds,omitempty"`
 
 	// Selector is a label query over pods that should match the pod count.
+	// Normally, the system sets this field for you.
 	// More info: http://releases.k8s.io/HEAD/docs/user-guide/labels.md#label-selectors
 	Selector *LabelSelector `json:"selector,omitempty"`
 
+	// AutoSelector controls generation of pod labels and pod selectors.
+	// It was not present in the original extensions/v1beta1 Job definition, but exists
+	// to allow conversion from batch/v1 Jobs, where it corresponds to, but has the opposite
+	// meaning as, ManualSelector.
+	// More info: http://releases.k8s.io/HEAD/docs/design/selector-generation.md
+	AutoSelector *bool `json:"autoSelector,omitempty"`
+
 	// Template is the object that describes the pod that will be created when
 	// executing a job.
 	// More info: http://releases.k8s.io/HEAD/docs/user-guide/jobs.md

pkg/apis/extensions/validation/validation.go

@@ -379,9 +379,62 @@ func ValidateThirdPartyResourceData(obj *extensions.ThirdPartyResourceData) fiel
 	return allErrs
 }
 
+// TODO: generalize for other controller objects that will follow the same pattern, such as ReplicaSet and DaemonSet, and
+// move to new location.  Replace extensions.Job with an interface.
+//
+// ValidateGeneratedSelector validates that the generated selector on a controller object match the controller object
+// metadata, and the labels on the pod template are as generated.
+func ValidateGeneratedSelector(obj *extensions.Job) field.ErrorList {
+	allErrs := field.ErrorList{}
+	if obj.Spec.ManualSelector != nil && *obj.Spec.ManualSelector {
+		return allErrs
+	}
+
+	if obj.Spec.Selector == nil {
+		return allErrs // This case should already have been checked in caller.  No need for more errors.
+	}
+
+	// If somehow uid was unset then we would get "controller-uid=" as the selector
+	// which is bad.
+	if obj.ObjectMeta.UID == "" {
+		allErrs = append(allErrs, field.Required(field.NewPath("metadata").Child("uid"), ""))
+	}
+
+	// If somehow uid was unset then we would get "controller-uid=" as the selector
+	// which is bad.
+	if obj.ObjectMeta.UID == "" {
+		allErrs = append(allErrs, field.Required(field.NewPath("metadata").Child("uid"), ""))
+	}
+
+	// If selector generation was requested, then expected labels must be
+	// present on pod template, and much match job's uid and name.  The
+	// generated (not-manual) selectors/labels ensure no overlap with other
+	// controllers.  The manual mode allows orphaning, adoption,
+	// backward-compatibility, and experimentation with new
+	// labeling/selection schemes.  Automatic selector generation should
+	// have placed certain labels on the pod, but this could have failed if
+	// the user added coflicting labels.  Validate that the expected
+	// generated ones are there.
+
+	allErrs = append(allErrs, apivalidation.ValidateHasLabel(obj.Spec.Template.ObjectMeta, field.NewPath("spec").Child("template").Child("metadata"), "controller-uid", string(obj.UID))...)
+	allErrs = append(allErrs, apivalidation.ValidateHasLabel(obj.Spec.Template.ObjectMeta, field.NewPath("spec").Child("template").Child("metadata"), "job-name", string(obj.Name))...)
+	expectedLabels := make(map[string]string)
+	expectedLabels["controller-uid"] = string(obj.UID)
+	expectedLabels["job-name"] = string(obj.Name)
+	// Whether manually or automatically generated, the selector of the job must match the pods it will produce.
+	if selector, err := unversioned.LabelSelectorAsSelector(obj.Spec.Selector); err == nil {
+		if !selector.Matches(labels.Set(expectedLabels)) {
+			allErrs = append(allErrs, field.Invalid(field.NewPath("spec").Child("selector"), obj.Spec.Selector, "`selector` not auto-generated"))
+		}
+	}
+
+	return allErrs
+}
+
 func ValidateJob(job *extensions.Job) field.ErrorList {
 	// Jobs and rcs have the same name validation
 	allErrs := apivalidation.ValidateObjectMeta(&job.ObjectMeta, true, apivalidation.ValidateReplicationControllerName, field.NewPath("metadata"))
+	allErrs = append(allErrs, ValidateGeneratedSelector(job)...)
 	allErrs = append(allErrs, ValidateJobSpec(&job.Spec, field.NewPath("spec"))...)
 	return allErrs
 }
@@ -404,6 +457,7 @@ func ValidateJobSpec(spec *extensions.JobSpec, fldPath *field.Path) field.ErrorL
 		allErrs = append(allErrs, unversionedvalidation.ValidateLabelSelector(spec.Selector, fldPath.Child("selector"))...)
 	}
 
+	// Whether manually or automatically generated, the selector of the job must match the pods it will produce.
 	if selector, err := unversioned.LabelSelectorAsSelector(spec.Selector); err == nil {
 		labels := labels.Set(spec.Template.Labels)
 		if !selector.Matches(labels) {

pkg/apis/extensions/validation/validation_test.go

@@ -25,6 +25,7 @@ import (
 	"k8s.io/kubernetes/pkg/api/unversioned"
 	"k8s.io/kubernetes/pkg/apis/extensions"
 	"k8s.io/kubernetes/pkg/controller/podautoscaler"
+	"k8s.io/kubernetes/pkg/types"
 	"k8s.io/kubernetes/pkg/util/intstr"
 )
 
@@ -975,12 +976,15 @@ func TestValidateDeploymentRollback(t *testing.T) {
 }
 
 func TestValidateJob(t *testing.T) {
-	validSelector := &unversioned.LabelSelector{
+	validManualSelector := &unversioned.LabelSelector{
 		MatchLabels: map[string]string{"a": "b"},
 	}
-	validPodTemplateSpec := api.PodTemplateSpec{
+	validGeneratedSelector := &unversioned.LabelSelector{
+		MatchLabels: map[string]string{"collection-uid": "1a2b3c"},
+	}
+	validPodTemplateSpecForManual := api.PodTemplateSpec{
 		ObjectMeta: api.ObjectMeta{
-			Labels: validSelector.MatchLabels,
+			Labels: validManualSelector.MatchLabels,
 		},
 		Spec: api.PodSpec{
 			RestartPolicy: api.RestartPolicyOnFailure,
@@ -988,21 +992,45 @@ func TestValidateJob(t *testing.T) {
 			Containers:    []api.Container{{Name: "abc", Image: "image", ImagePullPolicy: "IfNotPresent"}},
 		},
 	}
-	successCases := []extensions.Job{
-		{
+	validPodTemplateSpecForGenerated := api.PodTemplateSpec{
+		ObjectMeta: api.ObjectMeta{
+			Labels: validGeneratedSelector.MatchLabels,
+		},
+		Spec: api.PodSpec{
+			RestartPolicy: api.RestartPolicyOnFailure,
+			DNSPolicy:     api.DNSClusterFirst,
+			Containers:    []api.Container{{Name: "abc", Image: "image", ImagePullPolicy: "IfNotPresent"}},
+		},
+	}
+	successCases := map[string]extensions.Job{
+		"manual selector": {
 			ObjectMeta: api.ObjectMeta{
 				Name:      "myjob",
 				Namespace: api.NamespaceDefault,
+				UID:       types.UID("1a2b3c"),
 			},
 			Spec: extensions.JobSpec{
-				Selector: validSelector,
-				Template: validPodTemplateSpec,
+				Selector:       validManualSelector,
+				ManualSelector: newBool(true),
+				Template:       validPodTemplateSpecForManual,
+			},
+		},
+		"generated selector": {
+			ObjectMeta: api.ObjectMeta{
+				Name:      "myjob",
+				Namespace: api.NamespaceDefault,
+				UID:       types.UID("1a2b3c"),
+			},
+			Spec: extensions.JobSpec{
+				Selector:       validGeneratedSelector,
+				ManualSelector: newBool(true),
+				Template:       validPodTemplateSpecForGenerated,
 			},
 		},
 	}
-	for _, successCase := range successCases {
-		if errs := ValidateJob(&successCase); len(errs) != 0 {
-			t.Errorf("expected success: %v", errs)
+	for k, v := range successCases {
+		if errs := ValidateJob(&v); len(errs) != 0 {
+			t.Errorf("expected success for %s: %v", k, errs)
 		}
 	}
 	negative := -1
@@ -1012,51 +1040,59 @@ func TestValidateJob(t *testing.T) {
 			ObjectMeta: api.ObjectMeta{
 				Name:      "myjob",
 				Namespace: api.NamespaceDefault,
+				UID:       types.UID("1a2b3c"),
 			},
 			Spec: extensions.JobSpec{
-				Parallelism: &negative,
-				Selector:    validSelector,
-				Template:    validPodTemplateSpec,
+				Parallelism:    &negative,
+				ManualSelector: newBool(true),
+				Template:       validPodTemplateSpecForGenerated,
 			},
 		},
 		"spec.completions:must be greater than or equal to 0": {
 			ObjectMeta: api.ObjectMeta{
 				Name:      "myjob",
 				Namespace: api.NamespaceDefault,
+				UID:       types.UID("1a2b3c"),
 			},
 			Spec: extensions.JobSpec{
-				Completions: &negative,
-				Selector:    validSelector,
-				Template:    validPodTemplateSpec,
+				Completions:    &negative,
+				Selector:       validManualSelector,
+				ManualSelector: newBool(true),
+				Template:       validPodTemplateSpecForGenerated,
 			},
 		},
 		"spec.activeDeadlineSeconds:must be greater than or equal to 0": {
 			ObjectMeta: api.ObjectMeta{
 				Name:      "myjob",
 				Namespace: api.NamespaceDefault,
+				UID:       types.UID("1a2b3c"),
 			},
 			Spec: extensions.JobSpec{
 				ActiveDeadlineSeconds: &negative64,
-				Selector:              validSelector,
-				Template:              validPodTemplateSpec,
+				Selector:              validManualSelector,
+				ManualSelector:        newBool(true),
+				Template:              validPodTemplateSpecForGenerated,
 			},
 		},
 		"spec.selector:Required value": {
 			ObjectMeta: api.ObjectMeta{
 				Name:      "myjob",
 				Namespace: api.NamespaceDefault,
+				UID:       types.UID("1a2b3c"),
 			},
 			Spec: extensions.JobSpec{
-				Template: validPodTemplateSpec,
+				Template: validPodTemplateSpecForGenerated,
 			},
 		},
 		"spec.template.metadata.labels: Invalid value: {\"y\":\"z\"}: `selector` does not match template `labels`": {
 			ObjectMeta: api.ObjectMeta{
 				Name:      "myjob",
 				Namespace: api.NamespaceDefault,
+				UID:       types.UID("1a2b3c"),
 			},
 			Spec: extensions.JobSpec{
-				Selector: validSelector,
+				Selector:       validManualSelector,
+				ManualSelector: newBool(true),
 				Template: api.PodTemplateSpec{
 					ObjectMeta: api.ObjectMeta{
 						Labels: map[string]string{"y": "z"},
@@ -1069,16 +1105,39 @@ func TestValidateJob(t *testing.T) {
 				},
 			},
 		},
+		"spec.template.metadata.labels: Invalid value: {\"controller-uid\":\"4d5e6f\"}: `selector` does not match template `labels`": {
+			ObjectMeta: api.ObjectMeta{
+				Name:      "myjob",
+				Namespace: api.NamespaceDefault,
+				UID:       types.UID("1a2b3c"),
+			},
+			Spec: extensions.JobSpec{
+				Selector:       validManualSelector,
+				ManualSelector: newBool(true),
+				Template: api.PodTemplateSpec{
+					ObjectMeta: api.ObjectMeta{
+						Labels: map[string]string{"controller-uid": "4d5e6f"},
+					},
+					Spec: api.PodSpec{
+						RestartPolicy: api.RestartPolicyOnFailure,
+						DNSPolicy:     api.DNSClusterFirst,
+						Containers:    []api.Container{{Name: "abc", Image: "image", ImagePullPolicy: "IfNotPresent"}},
+					},
+				},
+			},
+		},
 		"spec.template.spec.restartPolicy: Unsupported value": {
 			ObjectMeta: api.ObjectMeta{
 				Name:      "myjob",
 				Namespace: api.NamespaceDefault,
+				UID:       types.UID("1a2b3c"),
 			},
 			Spec: extensions.JobSpec{
-				Selector: validSelector,
+				Selector:       validManualSelector,
+				ManualSelector: newBool(true),
 				Template: api.PodTemplateSpec{
 					ObjectMeta: api.ObjectMeta{
-						Labels: validSelector.MatchLabels,
+						Labels: validManualSelector.MatchLabels,
 					},
 					Spec: api.PodSpec{
 						RestartPolicy: api.RestartPolicyAlways,
@@ -2070,3 +2129,9 @@ func TestValidatePodSecurityPolicy(t *testing.T) {
 		}
 	}
 }
+
+func newBool(val bool) *bool {
+	p := new(bool)
+	*p = val
+	return p
+}

pkg/kubectl/run.go

@@ -269,6 +269,7 @@ func (JobV1Beta1) Generate(genericParams map[string]interface{}) (runtime.Object
 			Selector: &unversioned.LabelSelector{
 				MatchLabels: labels,
 			},
+			ManualSelector: newBool(true),
 			Template: api.PodTemplateSpec{
 				ObjectMeta: api.ObjectMeta{
 					Labels: labels,
@@ -607,3 +608,9 @@ func parseEnvs(envArray []string) ([]api.EnvVar, error) {
 	}
 	return envs, nil
 }
+
+func newBool(val bool) *bool {
+	p := new(bool)
+	*p = val
+	return p
+}

pkg/kubectl/run_test.go

@@ -749,6 +749,7 @@ func TestGenerateJob(t *testing.T) {
 					Selector: &unversioned.LabelSelector{
 						MatchLabels: map[string]string{"foo": "bar", "baz": "blah"},
 					},
+					ManualSelector: newBool(true),
 					Template: api.PodTemplateSpec{
 						ObjectMeta: api.ObjectMeta{
 							Labels: map[string]string{"foo": "bar", "baz": "blah"},

pkg/registry/job/etcd/etcd_test.go

@@ -53,6 +53,7 @@ func validNewJob() *extensions.Job {
 			Selector: &unversioned.LabelSelector{
 				MatchLabels: map[string]string{"a": "b"},
 			},
+			ManualSelector: newBool(true),
 			Template: api.PodTemplateSpec{
 				ObjectMeta: api.ObjectMeta{
 					Labels: map[string]string{"a": "b"},
@@ -165,3 +166,9 @@ func TestWatch(t *testing.T) {
 }
 
 // TODO: test update /status
+
+func newBool(val bool) *bool {
+	p := new(bool)
+	*p = val
+	return p
+}

pkg/registry/job/strategy.go

@@ -21,6 +21,7 @@ import (
 	"strconv"
 
 	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/api/unversioned"
 	"k8s.io/kubernetes/pkg/apis/extensions"
 	"k8s.io/kubernetes/pkg/apis/extensions/validation"
 	"k8s.io/kubernetes/pkg/fields"
@@ -60,9 +61,63 @@ func (jobStrategy) PrepareForUpdate(obj, old runtime.Object) {
 // Validate validates a new job.
 func (jobStrategy) Validate(ctx api.Context, obj runtime.Object) field.ErrorList {
 	job := obj.(*extensions.Job)
+	// TODO: move UID generation earlier and do this in defaulting logic?
+	if job.Spec.ManualSelector == nil || *job.Spec.ManualSelector == false {
+		generateSelector(job)
+	}
 	return validation.ValidateJob(job)
 }
 
+// generateSelector adds a selector to a job and labels to its template
+// which can be used to uniquely identify the pods created by that job,
+// if the user has requested this behavior.
+func generateSelector(obj *extensions.Job) {
+	if obj.Spec.Template.Labels == nil {
+		obj.Spec.Template.Labels = make(map[string]string)
+	}
+	// The job-name label is unique except in cases that are expected to be
+	// quite uncommon, and is more user friendly than uid.  So, we add it as
+	// a label.
+	_, found := obj.Spec.Template.Labels["job-name"]
+	if found {
+		// User asked us to not automatically generate a selector and labels,
+		// but set a possibly conflicting value.  If there is a conflict,
+		// we will reject in validation.
+	} else {
+		obj.Spec.Template.Labels["job-name"] = string(obj.ObjectMeta.Name)
+	}
+	// The controller-uid label makes the pods that belong to this job
+	// only match this job.
+	_, found = obj.Spec.Template.Labels["controller-uid"]
+	if found {
+		// User asked us to automatically generate a selector and labels,
+		// but set a possibly conflicting value.  If there is a conflict,
+		// we will reject in validation.
+	} else {
+		obj.Spec.Template.Labels["controller-uid"] = string(obj.ObjectMeta.UID)
+	}
+	// Select the controller-uid label.  This is sufficient for uniqueness.
+	if obj.Spec.Selector == nil {
+		obj.Spec.Selector = &unversioned.LabelSelector{}
+	}
+	if obj.Spec.Selector.MatchLabels == nil {
+		obj.Spec.Selector.MatchLabels = make(map[string]string)
+	}
+	if _, found := obj.Spec.Selector.MatchLabels["controller-uid"]; !found {
+		obj.Spec.Selector.MatchLabels["controller-uid"] = string(obj.ObjectMeta.UID)
+	}
+	// If the user specified matchLabel controller-uid=$WRONGUID, then it should fail
+	// in validation, either because the selector does not match the pod template
+	// (controller-uid=$WRONGUID does not match controller-uid=$UID, which we applied
+	// above, or we will reject in validation because the template has the wrong
+	// labels.
+}
+
+// TODO: generalize generateSelector so it can work for other controller
+// objects such as ReplicaSet.  Can use pkg/api/meta to generically get the
+// UID, but need some way to generically access the selector and pod labels
+// fields.
+
 // Canonicalize normalizes the object after validation.
 func (jobStrategy) Canonicalize(obj runtime.Object) {
 }

pkg/registry/job/strategy_test.go

@@ -17,6 +17,7 @@ limitations under the License.
 package job
 
 import (
+	"reflect"
 	"testing"
 
 	"k8s.io/kubernetes/pkg/api"
@@ -25,8 +26,15 @@ import (
 	"k8s.io/kubernetes/pkg/api/unversioned"
 	"k8s.io/kubernetes/pkg/apis/extensions"
 	"k8s.io/kubernetes/pkg/labels"
+	"k8s.io/kubernetes/pkg/types"
 )
 
+func newBool(a bool) *bool {
+	r := new(bool)
+	*r = a
+	return r
+}
+
 func TestJobStrategy(t *testing.T) {
 	ctx := api.NewDefaultContext()
 	if !Strategy.NamespaceScoped() {
@@ -55,8 +63,9 @@ func TestJobStrategy(t *testing.T) {
 			Namespace: api.NamespaceDefault,
 		},
 		Spec: extensions.JobSpec{
-			Selector: validSelector,
-			Template: validPodTemplateSpec,
+			Selector:       validSelector,
+			Template:       validPodTemplateSpec,
+			ManualSelector: newBool(true),
 		},
 		Status: extensions.JobStatus{
 			Active: 11,
@@ -93,6 +102,56 @@ func TestJobStrategy(t *testing.T) {
 	}
 }
 
+func TestJobStrategyWithGeneration(t *testing.T) {
+	ctx := api.NewDefaultContext()
+
+	theUID := types.UID("1a2b3c4d5e6f7g8h9i0k")
+
+	validPodTemplateSpec := api.PodTemplateSpec{
+		Spec: api.PodSpec{
+			RestartPolicy: api.RestartPolicyOnFailure,
+			DNSPolicy:     api.DNSClusterFirst,
+			Containers:    []api.Container{{Name: "abc", Image: "image", ImagePullPolicy: "IfNotPresent"}},
+		},
+	}
+	job := &extensions.Job{
+		ObjectMeta: api.ObjectMeta{
+			Name:      "myjob2",
+			Namespace: api.NamespaceDefault,
+			UID:       theUID,
+		},
+		Spec: extensions.JobSpec{
+			Selector: nil,
+			Template: validPodTemplateSpec,
+		},
+	}
+
+	Strategy.PrepareForCreate(job)
+	errs := Strategy.Validate(ctx, job)
+	if len(errs) != 0 {
+		t.Errorf("Unexpected error validating %v", errs)
+	}
+
+	// Validate the stuff that validation should have validated.
+	if job.Spec.Selector == nil {
+		t.Errorf("Selector not generated")
+	}
+	expectedLabels := make(map[string]string)
+	expectedLabels["controller-uid"] = string(theUID)
+	if !reflect.DeepEqual(job.Spec.Selector.MatchLabels, expectedLabels) {
+		t.Errorf("Expected label selector not generated")
+	}
+	if job.Spec.Template.ObjectMeta.Labels == nil {
+		t.Errorf("Expected template labels not generated")
+	}
+	if v, ok := job.Spec.Template.ObjectMeta.Labels["job-name"]; !ok || v != "myjob2" {
+		t.Errorf("Expected template labels not present")
+	}
+	if v, ok := job.Spec.Template.ObjectMeta.Labels["controller-uid"]; !ok || v != string(theUID) {
+		t.Errorf("Expected template labels not present: ok: %v, v: %v", ok, v)
+	}
+}
+
 func TestJobStatusStrategy(t *testing.T) {
 	ctx := api.NewDefaultContext()
 	if !StatusStrategy.NamespaceScoped() {

test/e2e/job.go

@@ -204,8 +204,9 @@ func newTestJob(behavior, name string, rPol api.RestartPolicy, parallelism, comp
 			Name: name,
 		},
 		Spec: extensions.JobSpec{
-			Parallelism: &parallelism,
-			Completions: &completions,
+			Parallelism:    &parallelism,
+			Completions:    &completions,
+			ManualSelector: newBool(true),
 			Template: api.PodTemplateSpec{
 				ObjectMeta: api.ObjectMeta{
 					Labels: map[string]string{jobSelectorKey: name},
@@ -312,3 +313,9 @@ func waitForJobFail(c *client.Client, ns, jobName string) error {
 		return false, nil
 	})
 }
+
+func newBool(val bool) *bool {
+	p := new(bool)
+	*p = val
+	return p
+}

test/integration/master_test.go

@@ -204,26 +204,15 @@ var jobV1 string = `
     "kind": "Job",
     "apiVersion": "batch/v1",
     "metadata": {
-        "name": "pi",
-        "labels": {
-            "app": "pi"
-        }
+        "name": "pi"
     },
     "spec": {
         "parallelism": 1,
         "completions": 1,
-        "selector": {
-            "matchLabels": {
-                "app": "pi"
-            }
-        },
         "template": {
             "metadata": {
                 "name": "pi",
-                "creationTimestamp": null,
-                "labels": {
-                    "app": "pi"
-                }
+                "creationTimestamp": null
             },
             "spec": {
                 "containers": [