fix: retain non-nginx canary annotations. Fixes: #1070 (#3806)

fix: retain nginx canary annotations

Signed-off-by: Jahvon Dockery <jdockery@cargurus.com>

rollout/trafficrouting/nginx/nginx.go

@@ -325,6 +325,7 @@ func (r *Reconciler) SetWeightPerIngress(desiredWeight int32, ingresses []string
 		}
 
 		// Make patches
+		desiredCanaryIngress.SetAnnotations(getDesiredAnnotations(canaryIngress, desiredCanaryIngress))
 		patch, modified, err := ingressutil.BuildIngressPatch(canaryIngress.Mode(), canaryIngress,
 			desiredCanaryIngress, ingressutil.WithAnnotations(), ingressutil.WithLabels(), ingressutil.WithSpec())
 
@@ -371,3 +372,16 @@ func (r *Reconciler) SetMirrorRoute(setMirrorRoute *v1alpha1.SetMirrorRoute) err
 func (r *Reconciler) RemoveManagedRoutes() error {
 	return nil
 }
+
+func getDesiredAnnotations(current, desired *ingressutil.Ingress) map[string]string {
+	// Merge existing annotations into the desired Ingress (giving precedence to the desired values)
+	// This is necessary because the desired Ingress may not have all annotations previously added
+	// by other controllers (e.g. Rancher)
+	desiredAnnotations := desired.GetAnnotations()
+	for k, v := range current.GetAnnotations() {
+		if _, ok := desiredAnnotations[k]; !ok {
+			desiredAnnotations[k] = v
+		}
+	}
+	return desiredAnnotations
+}

rollout/trafficrouting/nginx/nginx_test.go

@@ -614,6 +614,37 @@ func TestCanaryIngressAdditionalAnnotationsNewIngress(t *testing.T) {
 	}
 }
 
+func TestCanaryIngressRetainCurrentAnnotations(t *testing.T) {
+	tests := generateMultiIngressTestData()
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			for _, ing := range test.ingresses {
+				r := Reconciler{
+					cfg: ReconcilerConfig{
+						Rollout: fakeRollout(stableService, canaryService, test.singleIngress, test.multiIngress),
+					},
+				}
+				stable := networkingIngress(StableIngress, 80, stableService)
+				stableIngress := ingressutil.NewIngress(stable)
+				canary := networkingIngress(ingressutil.GetCanaryIngressName(r.cfg.Rollout.GetName(), ing), 80, canaryService)
+				canary.SetAnnotations(map[string]string{
+					"nginx.ingress.kubernetes.io/canary":    "false",
+					"annotation-prefix.some.group/some-key": "some-value",
+				})
+				canaryIngress := ingressutil.NewIngress(canary)
+
+				desiredCanaryIngress, err := r.canaryIngress(stableIngress, ingressutil.GetCanaryIngressName(r.cfg.Rollout.GetName(), ing), 15)
+				assert.Nil(t, err, "No error returned when calling canaryIngress")
+
+				annotations := getDesiredAnnotations(canaryIngress, desiredCanaryIngress)
+				assert.Equal(t, "true", annotations["nginx.ingress.kubernetes.io/canary"], "canary annotation set to true")
+				assert.Equal(t, "15", annotations["nginx.ingress.kubernetes.io/canary-weight"], "canary-weight annotation set to expected value")
+				assert.Equal(t, "some-value", annotations["annotation-prefix.some.group/some-key"], "existing canary annotation is retained")
+			}
+		})
+	}
+}
+
 func TestCanaryIngressMaxWeightInTrafficRouting(t *testing.T) {
 	maxWeights := []*int32{nil, pointer.Int32(1000)}
 	for _, maxWeight := range maxWeights {