Use finalizers to avoid losing delete events and to ensure full resource cleanup (#941)

* Add Finalizer functions to Cluster; add/remove finalizer on Create/Delete events
* Check if clusters have a deletion timestamp and we missed that event. Run Delete() and remove finalizer when done.
* Fix nil handling when using Service from map; Remove Service, Endpoint entries from their maps - just like with Secrets
* Add handling of ResourceNotFound to all delete functions (Service, Endpoint, LogicalBackup CronJob, PDB and Secret) - this is not a real error when deleting things
* Emit events when there are issues deleting resources to the user is informed
* Depend the removal of the Finalizer on all resources being deleted successfully first. Otherwise the next sync run should let us try again
* Add config option to enable finalizers
* Removed dangling whitespace at EOL
* config.EnableFinalizers is a bool pointer

---------

Co-authored-by: Felix Kunde <felix-kunde@gmx.de>

Author: frittentheke

charts/postgres-operator/crds/operatorconfigurations.yaml

@@ -205,6 +205,9 @@ spec:
                   enable_cross_namespace_secret:
                     type: boolean
                     default: false
+                  enable_finalizers:
+                    type: boolean
+                    default: false
                   enable_init_containers:
                     type: boolean
                     default: true

charts/postgres-operator/values.yaml

@@ -123,6 +123,10 @@ configKubernetes:
 
   # allow user secrets in other namespaces than the Postgres cluster
   enable_cross_namespace_secret: false
+  # use finalizers to ensure all managed resources are deleted prior to the postgresql CR
+  # this avoids stale resources in case the operator misses a delete event or is not running
+  # during deletion
+  enable_finalizers: false
   # enables initContainers to run actions before Spilo is started
   enable_init_containers: true
   # toggles pod anti affinity on the Postgres pods
@@ -166,7 +170,7 @@ configKubernetes:
   # defines the template for PDB (Pod Disruption Budget) names
   pdb_name_format: "postgres-{cluster}-pdb"
   # specify the PVC retention policy when scaling down and/or deleting
-  persistent_volume_claim_retention_policy: 
+  persistent_volume_claim_retention_policy:
     when_deleted: "retain"
     when_scaled: "retain"
   # switches pod anti affinity type to `preferredDuringSchedulingIgnoredDuringExecution`

pkg/apis/acid.zalan.do/v1/operator_configuration_type.go

@@ -104,6 +104,7 @@ type KubernetesMetaConfiguration struct {
 	PersistentVolumeClaimRetentionPolicy     map[string]string   `json:"persistent_volume_claim_retention_policy,omitempty"`
 	EnableReadinessProbe                     bool                `json:"enable_readiness_probe,omitempty"`
 	EnableCrossNamespaceSecret               bool                `json:"enable_cross_namespace_secret,omitempty"`
+	EnableFinalizers                         *bool               `json:"enable_finalizers,omitempty"`
 }
 
 // PostgresPodResourcesDefaults defines the spec of default resources

pkg/cluster/cluster.go

@@ -13,6 +13,7 @@ import (
 	"sync"
 	"time"
 
+	jsonpatch "github.com/evanphx/json-patch"
 	"github.com/sirupsen/logrus"
 	acidv1 "github.com/zalando/postgres-operator/pkg/apis/acid.zalan.do/v1"
 
@@ -44,6 +45,7 @@ var (
 	databaseNameRegexp    = regexp.MustCompile("^[a-zA-Z_][a-zA-Z0-9_]*$")
 	userRegexp            = regexp.MustCompile(`^[a-z0-9]([-_a-z0-9]*[a-z0-9])?(\.[a-z0-9]([-_a-z0-9]*[a-z0-9])?)*$`)
 	patroniObjectSuffixes = []string{"leader", "config", "sync", "failover"}
+	finalizerName         = "postgres-operator.acid.zalan.do"
 )
 
 // Config contains operator-wide clients and configuration used from a cluster. TODO: remove struct duplication.
@@ -260,6 +262,12 @@ func (c *Cluster) Create() (err error) {
 	}()
 
 	c.KubeClient.SetPostgresCRDStatus(c.clusterName(), acidv1.ClusterStatusCreating)
+	if c.OpConfig.EnableFinalizers != nil && *c.OpConfig.EnableFinalizers {
+		c.logger.Info("Adding finalizer.")
+		if err = c.AddFinalizer(); err != nil {
+			return fmt.Errorf("could not add Finalizer: %v", err)
+		}
+	}
 	c.eventRecorder.Event(c.GetReference(), v1.EventTypeNormal, "Create", "Started creation of new cluster resources")
 
 	for _, role := range []PostgresRole{Master, Replica} {
@@ -763,6 +771,98 @@ func (c *Cluster) compareServices(old, new *v1.Service) (bool, string) {
 	return true, ""
 }
 
+// AddFinalizer patches the postgresql CR to add our finalizer.
+func (c *Cluster) AddFinalizer() error {
+	if c.HasFinalizer() {
+		c.logger.Debugf("Finalizer %s already exists.", finalizerName)
+		return nil
+	}
+
+	currentSpec := c.DeepCopy()
+	newSpec := c.DeepCopy()
+	newSpec.ObjectMeta.SetFinalizers(append(newSpec.ObjectMeta.Finalizers, finalizerName))
+	patchBytes, err := getPatchBytes(currentSpec, newSpec)
+	if err != nil {
+		return fmt.Errorf("Unable to produce patch to add finalizer: %v", err)
+	}
+
+	updatedSpec, err := c.KubeClient.AcidV1ClientSet.AcidV1().Postgresqls(c.clusterNamespace()).Patch(
+		context.TODO(), c.Name, types.MergePatchType, patchBytes, metav1.PatchOptions{})
+	if err != nil {
+		return fmt.Errorf("Could not add finalizer: %v", err)
+	}
+
+	// update the spec, maintaining the new resourceVersion.
+	c.setSpec(updatedSpec)
+	return nil
+}
+
+// RemoveFinalizer patches postgresql CR to remove finalizer.
+func (c *Cluster) RemoveFinalizer() error {
+	if !c.HasFinalizer() {
+		c.logger.Debugf("No finalizer %s exists to remove.", finalizerName)
+		return nil
+	}
+	currentSpec := c.DeepCopy()
+	newSpec := c.DeepCopy()
+	newSpec.ObjectMeta.SetFinalizers(removeString(newSpec.ObjectMeta.Finalizers, finalizerName))
+	patchBytes, err := getPatchBytes(currentSpec, newSpec)
+	if err != nil {
+		return fmt.Errorf("Unable to produce patch to remove finalizer: %v", err)
+	}
+
+	updatedSpec, err := c.KubeClient.AcidV1ClientSet.AcidV1().Postgresqls(c.clusterNamespace()).Patch(
+		context.TODO(), c.Name, types.MergePatchType, patchBytes, metav1.PatchOptions{})
+	if err != nil {
+		return fmt.Errorf("Could not remove finalizer: %v", err)
+	}
+
+	// update the spec, maintaining the new resourceVersion.
+	c.setSpec(updatedSpec)
+
+	return nil
+}
+
+// HasFinalizer checks if our finalizer is currently set or not
+func (c *Cluster) HasFinalizer() bool {
+	for _, finalizer := range c.ObjectMeta.Finalizers {
+		if finalizer == finalizerName {
+			return true
+		}
+	}
+	return false
+}
+
+// Iterate through slice and remove certain string, then return cleaned slice
+func removeString(slice []string, s string) (result []string) {
+	for _, item := range slice {
+		if item == s {
+			continue
+		}
+		result = append(result, item)
+	}
+	return result
+}
+
+// getPatchBytes will produce a JSONpatch between the two parameters of type acidv1.Postgresql
+func getPatchBytes(oldSpec, newSpec *acidv1.Postgresql) ([]byte, error) {
+	oldData, err := json.Marshal(oldSpec)
+	if err != nil {
+		return nil, fmt.Errorf("failed to Marshal oldSpec for postgresql %s/%s: %v", oldSpec.Namespace, oldSpec.Name, err)
+	}
+
+	newData, err := json.Marshal(newSpec)
+	if err != nil {
+		return nil, fmt.Errorf("failed to Marshal newSpec for postgresql %s/%s: %v", newSpec.Namespace, newSpec.Name, err)
+	}
+
+	patchBytes, err := jsonpatch.CreateMergePatch(oldData, newData)
+	if err != nil {
+		return nil, fmt.Errorf("failed to CreateMergePatch for postgresl %s/%s: %v", oldSpec.Namespace, oldSpec.Name, err)
+	}
+	return patchBytes, nil
+}
+
 // Update changes Kubernetes objects according to the new specification. Unlike the sync case, the missing object
 // (i.e. service) is treated as an error
 // logical backup cron jobs are an exception: a user-initiated Update can enable a logical backup job
@@ -1005,59 +1105,88 @@ func syncResources(a, b *v1.ResourceRequirements) bool {
 // DCS, reuses the master's endpoint to store the leader related metadata. If we remove the endpoint
 // before the pods, it will be re-created by the current master pod and will remain, obstructing the
 // creation of the new cluster with the same name. Therefore, the endpoints should be deleted last.
-func (c *Cluster) Delete() {
+func (c *Cluster) Delete() error {
 	c.mu.Lock()
 	defer c.mu.Unlock()
-	c.eventRecorder.Event(c.GetReference(), v1.EventTypeNormal, "Delete", "Started deletion of new cluster resources")
+	c.eventRecorder.Event(c.GetReference(), v1.EventTypeNormal, "Delete", "Started deletion of cluster resources")
 
 	if err := c.deleteStreams(); err != nil {
 		c.logger.Warningf("could not delete event streams: %v", err)
+		c.eventRecorder.Eventf(c.GetReference(), v1.EventTypeWarning, "Delete", "Could not delete event streams: %v", err)
 	}
+	var anyErrors = false
 
 	// delete the backup job before the stateful set of the cluster to prevent connections to non-existing pods
 	// deleting the cron job also removes pods and batch jobs it created
 	if err := c.deleteLogicalBackupJob(); err != nil {
+		anyErrors = true
 		c.logger.Warningf("could not remove the logical backup k8s cron job; %v", err)
+		c.eventRecorder.Eventf(c.GetReference(), v1.EventTypeWarning, "Delete", "Could not remove the logical backup k8s cron job; %v", err)
 	}
 
 	if err := c.deleteStatefulSet(); err != nil {
+		anyErrors = true
 		c.logger.Warningf("could not delete statefulset: %v", err)
+		c.eventRecorder.Eventf(c.GetReference(), v1.EventTypeWarning, "Delete", "Could not delete statefulset: %v", err)
 	}
 
 	if err := c.deleteSecrets(); err != nil {
+		anyErrors = true
 		c.logger.Warningf("could not delete secrets: %v", err)
+		c.eventRecorder.Eventf(c.GetReference(), v1.EventTypeWarning, "Delete", "Could not delete secrets: %v", err)
 	}
 
 	if err := c.deletePodDisruptionBudget(); err != nil {
+		anyErrors = true
 		c.logger.Warningf("could not delete pod disruption budget: %v", err)
+		c.eventRecorder.Eventf(c.GetReference(), v1.EventTypeWarning, "Delete", "Could not delete pod disruption budget: %v", err)
 	}
 
 	for _, role := range []PostgresRole{Master, Replica} {
 
 		if !c.patroniKubernetesUseConfigMaps() {
 			if err := c.deleteEndpoint(role); err != nil {
+				anyErrors = true
 				c.logger.Warningf("could not delete %s endpoint: %v", role, err)
+				c.eventRecorder.Eventf(c.GetReference(), v1.EventTypeWarning, "Delete", "Could not delete %s endpoint: %v", role, err)
 			}
 		}
 
 		if err := c.deleteService(role); err != nil {
+			anyErrors = true
 			c.logger.Warningf("could not delete %s service: %v", role, err)
+			c.eventRecorder.Eventf(c.GetReference(), v1.EventTypeWarning, "Delete", "Could not delete %s service: %v", role, err)
 		}
 	}
 
 	if err := c.deletePatroniClusterObjects(); err != nil {
+		anyErrors = true
 		c.logger.Warningf("could not remove leftover patroni objects; %v", err)
+		c.eventRecorder.Eventf(c.GetReference(), v1.EventTypeWarning, "Delete", "Could not remove leftover patroni objects; %v", err)
 	}
 
 	// Delete connection pooler objects anyway, even if it's not mentioned in the
 	// manifest, just to not keep orphaned components in case if something went
 	// wrong
 	for _, role := range [2]PostgresRole{Master, Replica} {
 		if err := c.deleteConnectionPooler(role); err != nil {
+			anyErrors = true
 			c.logger.Warningf("could not remove connection pooler: %v", err)
+			c.eventRecorder.Eventf(c.GetReference(), v1.EventTypeWarning, "Delete", "Could not remove connection pooler: %v", err)
 		}
 	}
 
+	// If we are done deleting our various resources we remove the finalizer to let K8S finally delete the Postgres CR
+	if anyErrors {
+		c.eventRecorder.Event(c.GetReference(), v1.EventTypeWarning, "Delete", "Some resources could be successfully deleted yet")
+		return fmt.Errorf("some error(s) occured when deleting resources, NOT removing finalizer yet")
+	}
+	if err := c.RemoveFinalizer(); err != nil {
+		return fmt.Errorf("Done cleaning up, but error when trying to remove our finalizer: %v", err)
+	}
+
+	c.logger.Info("Done cleaning up our resources, removed finalizer.")
+	return nil
 }
 
 // NeedsRepair returns true if the cluster should be included in the repair scan (based on its in-memory status).

pkg/cluster/resources.go

@@ -247,9 +247,12 @@ func (c *Cluster) deleteStatefulSet() error {
 	}
 
 	err := c.KubeClient.StatefulSets(c.Statefulset.Namespace).Delete(context.TODO(), c.Statefulset.Name, c.deleteOptions)
-	if err != nil {
+	if k8sutil.ResourceNotFound(err) {
+		c.logger.Debugf("StatefulSet was already deleted")
+	} else if err != nil {
 		return err
 	}
+
 	c.logger.Infof("statefulset %q has been deleted", util.NameFromMeta(c.Statefulset.ObjectMeta))
 	c.Statefulset = nil
 
@@ -336,18 +339,21 @@ func (c *Cluster) updateService(role PostgresRole, oldService *v1.Service, newSe
 func (c *Cluster) deleteService(role PostgresRole) error {
 	c.logger.Debugf("deleting service %s", role)
 
-	service, ok := c.Services[role]
-	if !ok {
+	if c.Services[role] == nil {
 		c.logger.Debugf("No service for %s role was found, nothing to delete", role)
 		return nil
 	}
 
-	if err := c.KubeClient.Services(service.Namespace).Delete(context.TODO(), service.Name, c.deleteOptions); err != nil {
-		return err
+	if err := c.KubeClient.Services(c.Services[role].Namespace).Delete(context.TODO(), c.Services[role].Name, c.deleteOptions); err != nil {
+		if k8sutil.ResourceNotFound(err) {
+			c.logger.Debugf("Service was already deleted")
+		} else if err != nil {
+			return err
+		}
 	}
 
-	c.logger.Infof("%s service %q has been deleted", role, util.NameFromMeta(service.ObjectMeta))
-	c.Services[role] = nil
+	c.logger.Infof("%s service %q has been deleted", role, util.NameFromMeta(c.Services[role].ObjectMeta))
+	delete(c.Services, role)
 
 	return nil
 }
@@ -448,9 +454,12 @@ func (c *Cluster) deletePodDisruptionBudget() error {
 	err := c.KubeClient.
 		PodDisruptionBudgets(c.PodDisruptionBudget.Namespace).
 		Delete(context.TODO(), c.PodDisruptionBudget.Name, c.deleteOptions)
-	if err != nil {
-		return fmt.Errorf("could not delete pod disruption budget: %v", err)
+	if k8sutil.ResourceNotFound(err) {
+		c.logger.Debugf("PodDisruptionBudget was already deleted")
+	} else if err != nil {
+		return fmt.Errorf("could not delete PodDisruptionBudget: %v", err)
 	}
+
 	c.logger.Infof("pod disruption budget %q has been deleted", util.NameFromMeta(c.PodDisruptionBudget.ObjectMeta))
 	c.PodDisruptionBudget = nil
 
@@ -479,14 +488,16 @@ func (c *Cluster) deleteEndpoint(role PostgresRole) error {
 		return fmt.Errorf("there is no %s endpoint in the cluster", role)
 	}
 
-	if err := c.KubeClient.Endpoints(c.Endpoints[role].Namespace).Delete(
-		context.TODO(), c.Endpoints[role].Name, c.deleteOptions); err != nil {
-		return fmt.Errorf("could not delete endpoint: %v", err)
+	if err := c.KubeClient.Endpoints(c.Endpoints[role].Namespace).Delete(context.TODO(), c.Endpoints[role].Name, c.deleteOptions); err != nil {
+		if k8sutil.ResourceNotFound(err) {
+			c.logger.Debugf("Endpoint was already deleted")
+		} else if err != nil {
+			return fmt.Errorf("could not delete endpoint: %v", err)
+		}
 	}
 
 	c.logger.Infof("endpoint %q has been deleted", util.NameFromMeta(c.Endpoints[role].ObjectMeta))
-
-	c.Endpoints[role] = nil
+	delete(c.Endpoints, role)
 
 	return nil
 }
@@ -514,7 +525,9 @@ func (c *Cluster) deleteSecret(uid types.UID, secret v1.Secret) error {
 	secretName := util.NameFromMeta(secret.ObjectMeta)
 	c.logger.Debugf("deleting secret %q", secretName)
 	err := c.KubeClient.Secrets(secret.Namespace).Delete(context.TODO(), secret.Name, c.deleteOptions)
-	if err != nil {
+	if k8sutil.ResourceNotFound(err) {
+		c.logger.Debugf("Secret was already deleted")
+	} else if err != nil {
 		return fmt.Errorf("could not delete secret %q: %v", secretName, err)
 	}
 	c.logger.Infof("secret %q has been deleted", secretName)
@@ -573,7 +586,14 @@ func (c *Cluster) deleteLogicalBackupJob() error {
 
 	c.logger.Info("removing the logical backup job")
 
-	return c.KubeClient.CronJobsGetter.CronJobs(c.Namespace).Delete(context.TODO(), c.getLogicalBackupJobName(), c.deleteOptions)
+	err := c.KubeClient.CronJobsGetter.CronJobs(c.Namespace).Delete(context.TODO(), c.getLogicalBackupJobName(), c.deleteOptions)
+	if k8sutil.ResourceNotFound(err) {
+		c.logger.Debugf("LogicalBackup CronJob was already deleted")
+	} else if err != nil {
+		return err
+	}
+
+	return nil
 }
 
 // GetServiceMaster returns cluster's kubernetes master Service

pkg/controller/operator_config.go

@@ -91,6 +91,7 @@ func (c *Controller) importConfigurationFromCRD(fromCRD *acidv1.OperatorConfigur
 	result.SecretNameTemplate = fromCRD.Kubernetes.SecretNameTemplate
 	result.OAuthTokenSecretName = fromCRD.Kubernetes.OAuthTokenSecretName
 	result.EnableCrossNamespaceSecret = fromCRD.Kubernetes.EnableCrossNamespaceSecret
+	result.EnableFinalizers = util.CoalesceBool(fromCRD.Kubernetes.EnableFinalizers, util.False())
 
 	result.InfrastructureRolesSecretName = fromCRD.Kubernetes.InfrastructureRolesSecretName
 	if fromCRD.Kubernetes.InfrastructureRolesDefs != nil {