Validate longest pod name for jobset will not exceed 63 chars

api/jobset/v1alpha2/jobset_webhook.go

@@ -17,6 +17,7 @@ import (
 	"errors"
 	"fmt"
 	"math"
+	"strconv"
 
 	apivalidation "k8s.io/apimachinery/pkg/api/validation"
 	"k8s.io/apimachinery/pkg/runtime"
@@ -105,10 +106,21 @@ func (js *JobSet) ValidateCreate() (admission.Warnings, error) {
 		}
 		// Check that the generated job names for this replicated job will be DNS 1035 compliant.
 		// Use the largest job index as it will have the longest name.
-		testJobName := placement.GenJobName(js.Name, rjob.Name, int(rjob.Replicas-1))
-		for _, errMessage := range validation.IsDNS1035Label(testJobName) {
+		longestJobName := placement.GenJobName(js.Name, rjob.Name, int(rjob.Replicas-1))
+		for _, errMessage := range validation.IsDNS1035Label(longestJobName) {
 			allErrs = append(allErrs, fmt.Errorf(errMessage))
 		}
+		// Check that the generated pod names for the replicated job is DNS 1035 compliant.
+		isIndexedJob := rjob.Template.Spec.CompletionMode != nil && *rjob.Template.Spec.CompletionMode == batchv1.IndexedCompletion
+		if isIndexedJob && rjob.Template.Spec.Completions != nil {
+			maxJobIndex := strconv.Itoa(int(rjob.Replicas - 1))
+			maxPodIndex := strconv.Itoa(int(*rjob.Template.Spec.Completions - 1))
+			// Add 5 char suffix to the deterministic part of the pod name to validate the full pod name is compliant.
+			longestPodName := placement.GenPodName(js.Name, rjob.Name, maxJobIndex, maxPodIndex) + "-abcde"
+			for _, errMessage := range validation.IsDNS1035Label(longestPodName) {
+				allErrs = append(allErrs, fmt.Errorf(errMessage))
+			}
+		}
 	}
 	for _, rjobName := range js.Spec.SuccessPolicy.TargetReplicatedJobs {
 		if !collections.Contains(validReplicatedJobs, rjobName) {

api/jobset/v1alpha2/jobset_webhook_test.go

@@ -510,6 +510,33 @@ func TestValidateCreate(t *testing.T) {
 				fmt.Errorf("must be no more than 63 characters"),
 			),
 		},
+		{
+			name: "jobset name will result in a pod name being too long",
+			js: &JobSet{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: strings.Repeat("a", 56),
+				},
+				Spec: JobSetSpec{
+					ReplicatedJobs: []ReplicatedJob{
+						{
+							Name:     "rj",
+							Replicas: 1,
+							Template: batchv1.JobTemplateSpec{
+								Spec: batchv1.JobSpec{
+									CompletionMode: ptr.To(batchv1.IndexedCompletion),
+									Completions:    ptr.To(int32(1)),
+									Parallelism:    ptr.To(int32(1)),
+								},
+							},
+						},
+					},
+					SuccessPolicy: &SuccessPolicy{},
+				},
+			},
+			want: errors.Join(
+				fmt.Errorf("must be no more than 63 characters"),
+			),
+		},
 	}
 
 	for _, tc := range testCases {

pkg/util/placement/placement.go

@@ -15,10 +15,10 @@ func GenJobName(jsName, rjobName string, jobIndex int) string {
 	return fmt.Sprintf("%s-%s-%d", jsName, rjobName, jobIndex)
 }
 
-// GenLeaderPodName returns the name of the leader pod (pod with completion index 0)
-// for a given job in a jobset.
-func GenLeaderPodName(jobSet, replicatedJob, jobIndex string) string {
-	return fmt.Sprintf("%s-%s-%s-0", jobSet, replicatedJob, jobIndex)
+// GenPodName returns the pod name for the given JobSet name, ReplicatedJob name,
+// Job index, and Pod index.
+func GenPodName(jobSet, replicatedJob, jobIndex, podIndex string) string {
+	return fmt.Sprintf("%s-%s-%s-%s", jobSet, replicatedJob, jobIndex, podIndex)
 }
 
 // IsLeaderPod returns true if the given pod is a leader pod (job completion index of 0),

pkg/webhooks/pod_admission_webhook.go

@@ -107,7 +107,7 @@ func (p *podWebhook) leaderPodForFollower(ctx context.Context, pod *corev1.Pod)
 	return leaderPod, nil
 }
 
-// GenLeaderPodName accepts the name of a pod that is part of a jobset as input, and
+// genLeaderPodName accepts the name of a pod that is part of a jobset as input, and
 // returns the name of the pod with completion index 0 in the same child job.
 func genLeaderPodName(pod *corev1.Pod) (string, error) {
 	// Pod name format: <jobset>-<replicatedJob>-<jobIndex>-<podIndex>-<randomSuffix>
@@ -123,5 +123,6 @@ func genLeaderPodName(pod *corev1.Pod) (string, error) {
 	if !ok {
 		return "", fmt.Errorf("pod missing label: %s", jobset.JobIndexKey)
 	}
-	return placement.GenLeaderPodName(jobSet, replicatedJob, jobIndex), nil
+	leaderPodName := placement.GenPodName(jobSet, replicatedJob, jobIndex, "0")
+	return leaderPodName, nil
 }

pkg/webhooks/pod_admission_webhook_test.go

@@ -10,7 +10,7 @@ import (
 	jobset "sigs.k8s.io/jobset/api/jobset/v1alpha2"
 )
 
-func TestGenLeaderPodName(t *testing.T) {
+func TestLeaderPodName(t *testing.T) {
 	cases := []struct {
 		desc    string
 		pod     *corev1.Pod