Apply 'app' and 'version' labels to Server Pods (#119)

Applies 'app' and 'version' labels to Server Pods. This is a fairly
common Kubernetes standard, and also allows better tracing in Kiali for
Istio mesh network visualization.

Reference: https://linear.app/prefect/issue/PLA-410/istio-investigate-ambient-mode#comment-3ade7c6c

Related to PLA-410

api/v1/prefectserver_types.go

@@ -237,6 +237,8 @@ type PrefectServer struct {
 func (s *PrefectServer) ServerLabels() map[string]string {
 	labels := map[string]string{
 		"prefect.io/server": s.Name,
+		"app":               "prefect-server",
+		"version":           s.getVersion(),
 	}
 	for k, v := range s.Spec.DeploymentLabels {
 		labels[k] = v
@@ -339,3 +341,14 @@ type PrefectServerList struct {
 func init() {
 	SchemeBuilder.Register(&PrefectServer{}, &PrefectServerList{})
 }
+
+// getVersion returns the version of Prefect.
+// The `.spec.version` field is optional, so if it is
+// not configured, we return the default version.
+func (s *PrefectServer) getVersion() string {
+	if s.Spec.Version != nil && *s.Spec.Version != "" {
+		return *s.Spec.Version
+	}
+
+	return DEFAULT_PREFECT_VERSION
+}

internal/controller/prefectserver_controller_test.go

@@ -119,13 +119,15 @@ var _ = Describe("PrefectServer controller", func() {
 		})
 
 		It("should allow specifying a Prefect version", func() {
+			version := "3.3.3.3.3.3.3.3"
+			expectedImage := fmt.Sprintf("prefecthq/prefect:%s-python3.12", version)
 			prefectserver = &prefectiov1.PrefectServer{
 				ObjectMeta: metav1.ObjectMeta{
 					Namespace: namespaceName,
 					Name:      "prefect-on-anything",
 				},
 				Spec: prefectiov1.PrefectServerSpec{
-					Version: ptr.To("3.3.3.3.3.3.3.3"),
+					Version: &version,
 				},
 			}
 			Expect(k8sClient.Create(ctx, prefectserver)).To(Succeed())
@@ -153,7 +155,9 @@ var _ = Describe("PrefectServer controller", func() {
 
 			Expect(deployment.Spec.Template.Spec.Containers).To(HaveLen(1))
 			container := deployment.Spec.Template.Spec.Containers[0]
-			Expect(container.Image).To(Equal("prefecthq/prefect:3.3.3.3.3.3.3.3-python3.12"))
+			Expect(container.Image).To(Equal(expectedImage))
+			Expect(deployment.Spec.Selector.MatchLabels).To(HaveKeyWithValue("version", version))
+			Expect(deployment.Spec.Template.ObjectMeta.Labels).To(HaveKeyWithValue("version", version))
 		})
 
 		Context("when creating any server", func() {
@@ -269,11 +273,15 @@ var _ = Describe("PrefectServer controller", func() {
 				It("should have appropriate labels", func() {
 					Expect(deployment.Spec.Selector.MatchLabels).To(Equal(map[string]string{
 						"prefect.io/server": "prefect-on-anything",
+						"app":               "prefect-server",
+						"version":           prefectiov1.DEFAULT_PREFECT_VERSION,
 						"some":              "additional-label",
 						"another":           "extra-label",
 					}))
 					Expect(deployment.Spec.Template.Labels).To(Equal(map[string]string{
 						"prefect.io/server": "prefect-on-anything",
+						"app":               "prefect-server",
+						"version":           prefectiov1.DEFAULT_PREFECT_VERSION,
 						"some":              "additional-label",
 						"another":           "extra-label",
 					}))