Remove emptyDir volume support

The operator was using emptyDir storage if the user didn't specify a
StorageClass to be used. Given that the `emptyDir` storage is ephimeral and
meant to be used only when bootstrapping a development environment, we decided
that this wasn't a safe default.

We now require the user to specify a size requirement and, if the StorageClass
is empty, we let k8s use the default storage class of the cluster.

Co-authored-by: Leonardo Cecchi <leonardo.cecchi@2ndquadrant.it>
Co-authored-by: Marco Nenciarini <marco.nenciarini@2ndquadrant.it>

NEWS

@@ -1,6 +1,12 @@
 Cloud Native PostgreSQL  - History of user-visible changes
 Copyright (C) 2019-2020 2ndQuadrant Italia SRL. Exclusively licensed to 2ndQuadrant Limited.
 
+Version 0.3.0 - TODO
+
+- Remove EmptyDir storage support
+- Remove "unusable" annotation support, now PVC can just be removed followed
+  by a deletion of the corresponding Pod
+
 Version 0.2.0 - 11 Aug 2020
 
 - PostgreSQL 10 and 11 are now supported, in addition to PostgreSQL 12

README.md

@@ -5,16 +5,27 @@
 workloads on Kubernetes, particularly optimised for Private Cloud environments
 with Local Persistent Volumes (PV).
 
-## Quickstart for local testing (TODO)
+## Quickstart for local testing of a git branch
 
-Temporary information on how to test PG Operator using private images on Quay.io:
+If you want to deploy a cluster using the operator from your current git branch,
+you can use the following commands:
 
 ```bash
 kind create cluster --name pg
+kubectl create namespace postgresql-operator-system
+kubectl create secret docker-registry \
+    -n postgresql-operator-system \
+    postgresql-operator-pull-secret \
+    --docker-server=internal.2ndq.io \
+    --docker-username=$GITLAB_TOKEN_USERNAME \
+    --docker-password=$GITLAB_TOKEN_PASSWORD
 make deploy CONTROLLER_IMG=internal.2ndq.io/k8s/cloud-native-postgresql:$(git symbolic-ref --short HEAD | tr / _)
-kubectl apply -f docs/src/samples/cluster-emptydir.yaml
+kubectl apply -f docs/src/samples/cluster-example.yaml
 ```
 
+Replace `$GITLAB_TOKEN_USERNAME` and `$GITLAB_TOKEN_PASSWORD` with one with the permission to pull
+from the gitlab docker registry.
+
 # How to upgrade the list of licenses
 
 To generate or update the `licenses` folder run the following command:

api/v1alpha1/cluster_types.go

@@ -64,7 +64,7 @@ type ClusterSpec struct {
 
 	// Configuration of the storage of the instances
 	// +optional
-	StorageConfiguration *StorageConfiguration `json:"storage,omitempty"`
+	StorageConfiguration StorageConfiguration `json:"storage,omitempty"`
 
 	// The time in seconds that is allowed for a PostgreSQL instance to
 	// successfully start up (default 30)
@@ -191,12 +191,13 @@ type ApplicationConfiguration struct {
 type StorageConfiguration struct {
 	// StorageClass to use for database data (PGDATA). Applied after
 	// evaluating the PVC template, if available.
+	// If not specified, generated PVCs will be satisfied by the
+	// default storage class
 	// +optional
 	StorageClass *string `json:"storageClass"`
 
 	// Size of the storage. Required if not already specified in the PVC template.
-	// +optional
-	Size *resource.Quantity `json:"size"`
+	Size resource.Quantity `json:"size"`
 
 	// Template to be used to generate the Persistent Volume Claim
 	// +optional
@@ -387,12 +388,6 @@ func (cluster *Cluster) GetServiceReadWriteName() string {
 	return fmt.Sprintf("%v%v", cluster.Name, ServiceReadWriteSuffix)
 }
 
-// IsUsingPersistentStorage check if this cluster will use persistent storage
-// or not
-func (cluster *Cluster) IsUsingPersistentStorage() bool {
-	return cluster.Spec.StorageConfiguration != nil
-}
-
 // GetMaxStartDelay get the amount of time of startDelay config option
 func (cluster *Cluster) GetMaxStartDelay() int32 {
 	if cluster.Spec.MaxStartDelay > 0 {

api/v1alpha1/cluster_types_test.go

@@ -49,25 +49,6 @@ var _ = Describe("PostgreSQL services name", func() {
 	})
 })
 
-var _ = Describe("Detect persistent storage", func() {
-	It("by defaults work with emptyDir storage", func() {
-		var cluster = Cluster{}
-		Expect(cluster.IsUsingPersistentStorage()).To(BeFalse())
-	})
-
-	It("consider the presence of storage configuration", func() {
-		var storageClassName = "default-storage-class"
-		var cluster = Cluster{
-			Spec: ClusterSpec{
-				StorageConfiguration: &StorageConfiguration{
-					StorageClass: &storageClassName,
-				},
-			},
-		}
-		Expect(cluster.IsUsingPersistentStorage()).To(BeTrue())
-	})
-})
-
 var _ = Describe("Primary update strategy", func() {
 	It("defaults to switchover", func() {
 		emptyCluster := Cluster{}

config/crd/bases/postgresql.k8s.2ndq.io_clusters.yaml

@@ -388,8 +388,11 @@ spec:
                   x-kubernetes-int-or-string: true
                 storageClass:
                   description: StorageClass to use for database data (PGDATA). Applied
-                    after evaluating the PVC template, if available.
+                    after evaluating the PVC template, if available. If not specified,
+                    generated PVCs will be satisfied by the default storage class
                   type: string
+              required:
+              - size
               type: object
           required:
           - applicationConfiguration

controllers/cluster_create.go

@@ -347,14 +347,12 @@ func (r *ClusterReconciler) createPrimaryInstance(
 		return err
 	}
 
-	if cluster.IsUsingPersistentStorage() {
-		pvcSpec := specs.CreatePVC(*cluster.Spec.StorageConfiguration, cluster.Name, cluster.Namespace, nodeSerial)
-		utils.SetAsOwnedBy(&pvcSpec.ObjectMeta, cluster.ObjectMeta, cluster.TypeMeta)
-		specs.SetOperatorVersion(&pvcSpec.ObjectMeta, versions.Version)
-		if err = r.Create(ctx, pvcSpec); err != nil && !apierrs.IsAlreadyExists(err) {
-			log.Error(err, "Unable to create a PVC for this node", "nodeSerial", nodeSerial)
-			return err
-		}
+	pvcSpec := specs.CreatePVC(cluster.Spec.StorageConfiguration, cluster.Name, cluster.Namespace, nodeSerial)
+	utils.SetAsOwnedBy(&pvcSpec.ObjectMeta, cluster.ObjectMeta, cluster.TypeMeta)
+	specs.SetOperatorVersion(&pvcSpec.ObjectMeta, versions.Version)
+	if err = r.Create(ctx, pvcSpec); err != nil && !apierrs.IsAlreadyExists(err) {
+		log.Error(err, "Unable to create a PVC for this node", "nodeSerial", nodeSerial)
+		return err
 	}
 
 	return nil
@@ -395,14 +393,12 @@ func (r *ClusterReconciler) joinReplicaInstance(
 		return err
 	}
 
-	if cluster.IsUsingPersistentStorage() {
-		pvcSpec := specs.CreatePVC(*cluster.Spec.StorageConfiguration, cluster.Name, cluster.Namespace, nodeSerial)
-		utils.SetAsOwnedBy(&pvcSpec.ObjectMeta, cluster.ObjectMeta, cluster.TypeMeta)
-		specs.SetOperatorVersion(&pvcSpec.ObjectMeta, versions.Version)
-		if err = r.Create(ctx, pvcSpec); err != nil && !apierrs.IsAlreadyExists(err) {
-			log.Error(err, "Unable to create a PVC for this node", "nodeSerial", nodeSerial)
-			return err
-		}
+	pvcSpec := specs.CreatePVC(cluster.Spec.StorageConfiguration, cluster.Name, cluster.Namespace, nodeSerial)
+	utils.SetAsOwnedBy(&pvcSpec.ObjectMeta, cluster.ObjectMeta, cluster.TypeMeta)
+	specs.SetOperatorVersion(&pvcSpec.ObjectMeta, versions.Version)
+	if err = r.Create(ctx, pvcSpec); err != nil && !apierrs.IsAlreadyExists(err) {
+		log.Error(err, "Unable to create a PVC for this node", "nodeSerial", nodeSerial)
+		return err
 	}
 
 	return nil

controllers/cluster_scale.go

@@ -41,10 +41,6 @@ func (r *ClusterReconciler) scaleDownCluster(
 		return err
 	}
 
-	if !cluster.IsUsingPersistentStorage() {
-		return nil
-	}
-
 	// Let's drop the PVC too
 	pvc := v1.PersistentVolumeClaim{
 		ObjectMeta: metav1.ObjectMeta{

controllers/cluster_status.go

@@ -64,9 +64,7 @@ func (r *ClusterReconciler) updateResourceStatus(
 	filteredPods := utils.FilterActivePods(childPods.Items)
 
 	// Fill the list of dangling PVCs
-	if cluster.IsUsingPersistentStorage() {
-		cluster.Status.DanglingPVC = specs.DetectDanglingPVCs(filteredPods, childPVCs.Items)
-	}
+	cluster.Status.DanglingPVC = specs.DetectDanglingPVCs(filteredPods, childPVCs.Items)
 
 	// Count pods
 	cluster.Status.Instances = int32(len(filteredPods))

docs/src/expose_pg_services.md

@@ -4,7 +4,7 @@ NGINX Ingress Controller.
 
 If you followed the [QuickStart](/quickstart), you should have by now
 a database that can be accessed inside the cluster via the
-`cluster-emptydir-rw` (primary) and `cluster-emptydir-r` (read-only)
+`cluster-example-rw` (primary) and `cluster-example-r` (read-only)
 services in the `default` namespace. Both services use port `5432`.
 
 Let's assume that you want to make the primary instance accessible from external
@@ -49,7 +49,7 @@ metadata:
   name: tcp-services
   namespace: ingress-nginx
 data:
-  5432: default/cluster-emptydir-rw:5432
+  5432: default/cluster-example-rw:5432
 ```
 
 Then, if you've installed NGINX Ingress Controller as suggested in their
@@ -111,7 +111,7 @@ connections on port 5432 of the Ingress:
 
 ```sh
 kubectl patch configmap tcp-services -n kube-system \
-  --patch '{"data":{"5432":"default/cluster-emptydir-rw:5432"}}'
+  --patch '{"data":{"5432":"default/cluster-example-rw:5432"}}'
 ```
 
 You can then patch the deployment to allow access on port 5432.

docs/src/quickstart.md

@@ -89,15 +89,16 @@ kubectl get deploy -n postgresql-operator-system postgresql-operator-controller-
 As with any other deployment in Kubernetes, in order to deploy a PostgreSQL cluster
 you need to apply a configuration file that defines your desired `Cluster`.
 
-The [`cluster-emptydir.yaml`](samples/cluster-emptydir.yaml) sample file
-defines a simple `Cluster` with an `emptyDir` local volume:
+The [`cluster-example.yaml`](samples/cluster-example.yaml) sample file
+defines a simple `Cluster` using the default storage class to allocate
+disk space:
 
 ```yaml
-# Example of PostgreSQL cluster using emptyDir volumes
+# Example of PostgreSQL cluster
 apiVersion: postgresql.k8s.2ndq.io/v1alpha1
 kind: Cluster
 metadata:
-  name: cluster-emptydir
+  name: cluster-example
 spec:
   instances: 3
 
@@ -137,9 +138,13 @@ spec:
       # Require md5 authentication elsewhere
       - host all all all md5
       - host replication all all md5
+
+  # Require 1Gi of space
+  storage:
+    size: 1Gi
 ```
 
-This will create a `Cluster` called `cluster-emptydir` with a PostgreSQL
+This will create a `Cluster` called `cluster-example` with a PostgreSQL
 primary, two replicas, and a database called `app` owned by the `app` PostgreSQL user.
 
 !!! Note "There's more"
@@ -149,7 +154,7 @@ primary, two replicas, and a database called `app` owned by the `app` PostgreSQL
 In order to create the 3-node PostgreSQL cluster, you need to run the following command:
 
 ```sh
-kubectl apply -f cluster-emptydir.yaml
+kubectl apply -f cluster-example.yaml
 ```
 
 You can check that the pods are being created with the `get pods` command:

docs/src/rolling_update.md

@@ -25,14 +25,8 @@ Every version of the operator comes with a default PostgreSQL image version.
 If a cluster doesn't have `imageName` specified, the operator will upgrade
 it to match its default.
 
-If you are using persistent storage, which is a requirement for
-a production environment, the upgrade keeps the Cloud Native PostgreSQL
-identity and do not reclone the data.
-
-If you are using emptyDir based storage, which is meaningful only for
-a development environment, the operator cannot preserve the node
-data directory and must create new nodes and part those with
-the old version.
+The upgrade keeps the Cloud Native PostgreSQL identity and do not
+reclone the data.
 
 During the rolling update procedure, the services endpoints move to reflect
 the status of the cluster, so the applications ignore the node that

docs/src/samples.md

@@ -1,7 +1,7 @@
 In this section you can find some examples of configuration files to setup your PostgreSQL `Cluster`.
 
-* [`cluster-emptydir.yaml`](samples/cluster-emptydir.yaml):
-   basic example of `Cluster` that uses `emptyDir` local storage. For demonstration and experimentation purposes
+* [`cluster-example.yaml`](samples/cluster-example.yaml):
+   basic example of `Cluster` that uses the default storage class. For demonstration and experimentation purposes
    on a personal Kubernetes cluster with Minikube or Kind as described in the ["Quickstart"](quickstart.md).
 * [`cluster-storage-class.yaml`](samples/cluster-storage-class.yaml):
    basic example of `Cluster` that uses a specified storage class.

docs/src/samples/cluster-emptydir.yaml → docs/src/samples/cluster-example.yaml

@@ -1,8 +1,8 @@
-# Example of PostgreSQL cluster using emptyDir volumes
+# Example of PostgreSQL cluster
 apiVersion: postgresql.k8s.2ndq.io/v1alpha1
 kind: Cluster
 metadata:
-  name: cluster-emptydir
+  name: cluster-example
 spec:
   instances: 3
 
@@ -42,3 +42,7 @@ spec:
       # Require md5 authentication elsewhere
       - host all all all md5
       - host replication all all md5
+
+  # Require 1Gi of space
+  storage:
+    size: 1Gi

docs/src/samples/cluster-expose-service.yaml

@@ -5,7 +5,7 @@ metadata:
   name: tcp-services
   namespace: ingress-nginx
 data:
-  5432: default/cluster-emptydir-lead-primary:5432
+  5432: default/cluster-example-lead-primary:5432
 
 ---
 apiVersion: v1

pkg/specs/pods.go

@@ -167,8 +167,12 @@ func createImagePullSecrets(cluster v1alpha1.Cluster) []corev1.LocalObjectRefere
 func createPostgresVolumes(cluster v1alpha1.Cluster, podName string) []corev1.Volume {
 	return []corev1.Volume{
 		{
-			Name:         "pgdata",
-			VolumeSource: createVolumeSource(cluster, podName),
+			Name: "pgdata",
+			VolumeSource: corev1.VolumeSource{
+				PersistentVolumeClaim: &corev1.PersistentVolumeClaimVolumeSource{
+					ClaimName: podName,
+				},
+			},
 		},
 		{
 			Name: "config",
@@ -205,25 +209,6 @@ func createPostgresVolumes(cluster v1alpha1.Cluster, podName string) []corev1.Vo
 	}
 }
 
-// createVolumeSource create the VolumeSource environment that is used
-// when starting a container
-func createVolumeSource(cluster v1alpha1.Cluster, podName string) corev1.VolumeSource {
-	var pgDataVolumeSource corev1.VolumeSource
-	if cluster.IsUsingPersistentStorage() {
-		pgDataVolumeSource = corev1.VolumeSource{
-			PersistentVolumeClaim: &corev1.PersistentVolumeClaimVolumeSource{
-				ClaimName: podName,
-			},
-		}
-	} else {
-		pgDataVolumeSource = corev1.VolumeSource{
-			EmptyDir: &corev1.EmptyDirVolumeSource{},
-		}
-	}
-
-	return pgDataVolumeSource
-}
-
 // createPostgresContainers create the PostgreSQL containers that are
 // used for every instance
 func createPostgresContainers(

pkg/specs/pvcs.go

@@ -45,13 +45,11 @@ func CreatePVC(
 		result.Spec.StorageClassName = storageConfiguration.StorageClass
 	}
 
-	// If the customer specified a storage requirement, let's use it
-	if storageConfiguration.Size != nil {
-		result.Spec.Resources = corev1.ResourceRequirements{
-			Requests: corev1.ResourceList{
-				"storage": *storageConfiguration.Size,
-			},
-		}
+	// Insert the storage requirement
+	result.Spec.Resources = corev1.ResourceRequirements{
+		Requests: corev1.ResourceList{
+			"storage": storageConfiguration.Size,
+		},
 	}
 
 	if len(result.Spec.AccessModes) == 0 {