fix: stop keeping the sidecar forever on recovery-only clusters

A cluster bootstrapped only via RecoveryBarmanObjectName, with no
continuing archiving or replica source, only ever needs the sidecar
for its one-time bootstrap restore. Gate its injection on
cluster.IsInitialized() so it stops being added once the cluster is
up.

This makes the operator's own drift-check see the already-running
pod's spec as outdated right after initialization completes, and roll
it out to drop the sidecar. That is deliberately accepted rather than
engineered around: it is one deterministic rollout using the same
machinery the operator already uses for every other pod-spec change
(a switchover if a replica is available, an in-place restart
otherwise), not a new or fragile risk.

Signed-off-by: Marco Nenciarini <marco.nenciarini@enterprisedb.com>

internal/cnpgi/operator/lifecycle.go

@@ -322,6 +322,38 @@ func (impl LifecycleImplementation) collectAdditionalInstanceArgs(
 	return nil, nil
 }
 
+// shouldInjectBarmanSidecar decides whether an instance pod needs the
+// plugin-barman-cloud sidecar.
+//
+// A cluster doing backup/archiving or serving as a replica source needs the
+// sidecar in every instance pod for as long as the cluster exists, so those
+// two cases always inject it. A recovery-only cluster (only
+// RecoveryBarmanObjectName set, mirroring what pluginConfiguration.Validate()
+// accepts) only ever needs the sidecar for its one-time bootstrap restore, so
+// it's gated on cluster.IsInitialized() instead.
+//
+// Once the cluster finishes initializing, this makes the operator's own
+// drift-check (checkPodSpecIsOutdated) see the running pod's spec as outdated
+// and roll it out to drop the sidecar. That's deliberately accepted rather
+// than engineered around: it's one deterministic rollout using the same
+// machinery the operator already uses for every other pod-spec change (a
+// switchover if a replica is available, an in-place restart otherwise), not a
+// new or fragile risk.
+func shouldInjectBarmanSidecar(
+	cluster *cnpgv1.Cluster,
+	pluginConfiguration *config.PluginConfiguration,
+) bool {
+	if len(pluginConfiguration.BarmanObjectName) != 0 || len(pluginConfiguration.ReplicaSourceBarmanObjectName) != 0 {
+		return true
+	}
+
+	if len(pluginConfiguration.RecoveryBarmanObjectName) == 0 {
+		return false
+	}
+
+	return !cluster.IsInitialized()
+}
+
 func reconcileInstancePod(
 	ctx context.Context,
 	cluster *cnpgv1.Cluster,
@@ -339,11 +371,7 @@ func reconcileInstancePod(
 
 	mutatedPod := pod.DeepCopy()
 
-	// A recovery-only cluster (only RecoveryBarmanObjectName set) still needs the
+	if shouldInjectBarmanSidecar(cluster, pluginConfiguration) {
-	// sidecar in its instance pods: the phase-0 bootstrap restore and the WAL
-	// replay that follows both run inside the instance and rely on it. This
-	// condition therefore mirrors what pluginConfiguration.Validate() accepts.
-	if pluginConfiguration.HasAnyBarmanObjectStore() {
 		if err := reconcilePodSpec(
 			cluster,
 			&mutatedPod.Spec,
@@ -356,7 +384,7 @@ func reconcileInstancePod(
 			return nil, fmt.Errorf("while reconciling pod spec for pod: %w", err)
 		}
 	} else {
-		contextLogger.Debug("No need to mutate instance with no barman object store configuration")
+		contextLogger.Debug("No need to mutate instance, sidecar not required for this configuration and pod")
 	}
 
 	patch, err := object.CreatePatch(mutatedPod, pod)

internal/cnpgi/operator/lifecycle_test.go

@@ -265,6 +265,28 @@ var _ = Describe("LifecycleImplementation", func() {
 			Expect(patch).To(ContainElement(HaveKeyWithValue("path", "/spec/initContainers")))
 		})
 
+		It("does not inject the sidecar for a recovery-only cluster that has "+
+			"already completed its initial bootstrap", func(ctx SpecContext) {
+			recoveryOnlyConfig := &config.PluginConfiguration{
+				RecoveryBarmanObjectName: "minio-store-recovery",
+			}
+			cluster.Status.LatestGeneratedNode = 1
+			pod := &corev1.Pod{
+				TypeMeta:   podTypeMeta,
+				ObjectMeta: metav1.ObjectMeta{Name: "test-pod"},
+				Spec:       corev1.PodSpec{Containers: []corev1.Container{{Name: "postgres"}}},
+			}
+			podJSON, _ := json.Marshal(pod)
+			request := &lifecycle.OperatorLifecycleRequest{
+				ObjectDefinition: podJSON,
+			}
+
+			response, err := reconcileInstancePod(ctx, cluster, request, recoveryOnlyConfig, sidecarConfiguration{})
+			Expect(err).NotTo(HaveOccurred())
+			Expect(response).NotTo(BeNil())
+			Expect(response.JsonPatch).To(BeEmpty())
+		})
+
 		It("does not mutate the pod when no object store is configured", func(ctx SpecContext) {
 			emptyConfig := &config.PluginConfiguration{}
 			pod := &corev1.Pod{