feat: allow for stable cron names

The cron id is too long to store in the cronjob, so we generate a short identifier and look that up each time on deploy to ensure stability across time.

plugins/scheduler-k3s/k8s.go

@@ -165,6 +165,34 @@ func (k KubernetesClient) GetPod(ctx context.Context, input GetPodInput) (v1.Pod
 	return *pod, err
 }
 
+// ListCronJobsInput contains all the information needed to list Kubernetes cron jobs
+type ListCronJobsInput struct {
+	// LabelSelector is the Kubernetes label selector
+	LabelSelector string
+
+	// Namespace is the Kubernetes namespace
+	Namespace string
+}
+
+// ListCronJobs lists Kubernetes cron jobs
+func (k KubernetesClient) ListCronJobs(ctx context.Context, input ListCronJobsInput) ([]batchv1.CronJob, error) {
+	listOptions := metav1.ListOptions{}
+	if input.LabelSelector != "" {
+		listOptions.LabelSelector = input.LabelSelector
+	}
+
+	cronJobs, err := k.Client.BatchV1().CronJobs(input.Namespace).List(ctx, listOptions)
+	if err != nil {
+		return []batchv1.CronJob{}, err
+	}
+
+	if cronJobs == nil {
+		return []batchv1.CronJob{}, errors.New("cron jobs is nil")
+	}
+
+	return cronJobs.Items, err
+}
+
 // ListDeploymentsInput contains all the information needed to list Kubernetes deployments
 type ListDeploymentsInput struct {
 	// Namespace is the Kubernetes namespace

plugins/scheduler-k3s/template.go

@@ -76,6 +76,7 @@ type Job struct {
 	DeploymentID     int64
 	Entrypoint       string
 	Env              map[string]string
+	ID               string
 	Image            string
 	ImagePullSecrets string
 	ImageSourceType  string
@@ -84,6 +85,7 @@ type Job struct {
 	Namespace        string
 	ProcessType      string
 	Schedule         string
+	Suffix           string
 	RemoveContainer  bool
 	WorkingDir       string
 }
@@ -172,11 +174,13 @@ func templateKubernetesCronJob(input Job) (batchv1.CronJob, error) {
 	labels := map[string]string{
 		"dokku.com/app-name":         input.AppName,
 		"dokku.com/app-process-type": fmt.Sprintf("%s-%s", input.AppName, input.ProcessType),
+		"dokku.com/cron-id":          input.ID,
 		"dokku.com/process-type":     input.ProcessType,
 	}
 	annotations := map[string]string{
 		"dokku.com/app-name":      input.AppName,
 		"dokku.com/builder-type":  input.ImageSourceType,
+		"dokku.com/cron-id":       input.ID,
 		"dokku.com/deployment-id": "DEPLOYMENT_ID_QUOTED",
 		"dokku.com/managed":       "true",
 		"dokku.com/process-type":  input.ProcessType,
@@ -195,12 +199,23 @@ func templateKubernetesCronJob(input Job) (batchv1.CronJob, error) {
 		})
 	}
 
+	suffix := input.Suffix
+	if suffix == "" {
+		n := 5
+		b := make([]byte, n)
+		if _, err := rand.Read(b); err != nil {
+			panic(err)
+		}
+		suffix = strings.ToLower(fmt.Sprintf("%X", b))
+	}
+	annotations["dokku.com/job-suffix"] = suffix
+
 	job := batchv1.CronJob{
 		ObjectMeta: metav1.ObjectMeta{
-			GenerateName: fmt.Sprintf("%s-%s-", input.AppName, input.ProcessType),
-			Namespace:    input.Namespace,
-			Labels:       labels,
-			Annotations:  annotations,
+			Name:        fmt.Sprintf("%s-%s-%s", input.AppName, input.ProcessType, suffix),
+			Namespace:   input.Namespace,
+			Labels:      labels,
+			Annotations: annotations,
 		},
 		Spec: batchv1.CronJobSpec{
 			ConcurrencyPolicy:          batchv1.AllowConcurrent,
@@ -535,12 +550,16 @@ func templateKubernetesJob(input Job) (batchv1.Job, error) {
 		})
 	}
 
-	n := 5
-	b := make([]byte, n)
-	if _, err := rand.Read(b); err != nil {
-		panic(err)
+	suffix := input.Suffix
+	if suffix == "" {
+		n := 5
+		b := make([]byte, n)
+		if _, err := rand.Read(b); err != nil {
+			panic(err)
+		}
+		suffix = strings.ToLower(fmt.Sprintf("%X", b))
 	}
-	suffix := strings.ToLower(fmt.Sprintf("%X", b))
+	annotations["dokku.com/job-suffix"] = suffix
 
 	job := batchv1.Job{
 		ObjectMeta: metav1.ObjectMeta{

plugins/scheduler-k3s/triggers.go

@@ -276,7 +276,32 @@ data:
 	if err != nil {
 		return fmt.Errorf("Error fetching cron entries: %w", err)
 	}
+
+	clientset, err := NewKubernetesClient()
+	if err != nil {
+		return fmt.Errorf("Error creating kubernetes client: %w", err)
+	}
+
+	cronJobs, err := clientset.ListCronJobs(ctx, ListCronJobsInput{
+		LabelSelector: fmt.Sprintf("dokku.com/app-name=%s", appName),
+		Namespace:     namespace,
+	})
+	if err != nil {
+		return fmt.Errorf("Error listing cron jobs: %w", err)
+	}
+
 	for _, cronEntry := range cronEntries {
+		suffix := ""
+		for _, cronJob := range cronJobs {
+			if cronJob.Labels["dokku.com/cron-id"] == cronEntry.ID {
+				var ok bool
+				suffix, ok = cronJob.Annotations["dokku.com/job-suffix"]
+				if !ok {
+					suffix = ""
+				}
+			}
+		}
+
 		words, err := shellquote.Split(cronEntry.Command)
 		if err != nil {
 			return fmt.Errorf("Error parsing cron command: %w", err)
@@ -285,12 +310,14 @@ data:
 			AppName:          appName,
 			Command:          words,
 			Env:              map[string]string{},
+			ID:               cronEntry.ID,
 			Image:            image,
 			ImagePullSecrets: imagePullSecrets,
 			ImageSourceType:  imageSourceType,
 			Namespace:        namespace,
-			ProcessType:      cronEntry.ID,
+			ProcessType:      "cron",
 			Schedule:         cronEntry.Schedule,
+			Suffix:           suffix,
 			WorkingDir:       workingDir,
 		})
 		if err != nil {
@@ -916,8 +943,6 @@ func TriggerSchedulerRun(scheduler string, appName string, envCount int, args []
 			ProcessType: processType,
 			SelectedPod: selectedPod,
 		})
-
-		return nil
 	default:
 		return fmt.Errorf("Unable to attach as the pod is in an unknown state: %s", selectedPod.Status.Phase)
 	}