monitoring: allow overriding monitoring labels

The templates for the mgr-generated ServiceMonitor and PrometheusRule objects included the labels
prometheus and team, making it impossible to override them as user.

This adds a new method `OverwriteApplyToObjectMeta` to
pkg/apis/ceph.rook.io/v1.Labels, which, contrary to the existing
`ApplyToObjectMeta` method, overwrites existing labels.

Closes: https://github.com/rook/rook/issues/8502
Signed-off-by: Mara Sophie Grosch <littlefox@lf-net.org>

pkg/apis/ceph.rook.io/v1/labels.go

@@ -88,6 +88,16 @@ func (a Labels) ApplyToObjectMeta(t *metav1.ObjectMeta) {
 	}
 }
 
+// OverwriteApplyToObjectMeta adds labels to object meta, overwriting keys that are already defined.
+func (a Labels) OverwriteApplyToObjectMeta(t *metav1.ObjectMeta) {
+	if t.Labels == nil {
+		t.Labels = map[string]string{}
+	}
+	for k, v := range a {
+		t.Labels[k] = v
+	}
+}
+
 // Merge returns a Labels which results from merging the attributes of the
 // original Labels with the attributes of the supplied one. The supplied
 // Labels attributes will override the original ones if defined.

pkg/apis/ceph.rook.io/v1/labels_test.go

@@ -153,6 +153,60 @@ func TestLabelsApply(t *testing.T) {
 	}
 }
 
+func TestLabelsOverwriteApply(t *testing.T) {
+	tcs := []struct {
+		name     string
+		target   *metav1.ObjectMeta
+		input    Labels
+		expected Labels
+	}{
+		{
+			name:   "it should be able to update meta with no label",
+			target: &metav1.ObjectMeta{},
+			input: Labels{
+				"foo": "bar",
+			},
+			expected: Labels{
+				"foo": "bar",
+			},
+		},
+		{
+			name: "it should keep the original labels when new labels are set",
+			target: &metav1.ObjectMeta{
+				Labels: Labels{
+					"foo": "bar",
+				},
+			},
+			input: Labels{
+				"hello": "world",
+			},
+			expected: Labels{
+				"foo":   "bar",
+				"hello": "world",
+			},
+		},
+		{
+			name: "it should overwrite the existing keys",
+			target: &metav1.ObjectMeta{
+				Labels: Labels{
+					"foo": "bar",
+				},
+			},
+			input: Labels{
+				"foo": "baz",
+			},
+			expected: Labels{
+				"foo": "baz",
+			},
+		},
+	}
+
+	for _, tc := range tcs {
+		tc.input.OverwriteApplyToObjectMeta(tc.target)
+		assert.Equal(t, map[string]string(tc.expected), tc.target.Labels)
+	}
+}
+
 func TestLabelsMerge(t *testing.T) {
 	testLabelsPart1 := Labels{
 		"foo":   "bar",

pkg/operator/ceph/cluster/mgr/mgr.go

@@ -465,7 +465,7 @@ func (c *Cluster) EnableServiceMonitor(activeDaemon string) error {
 	}
 	serviceMonitor.SetName(AppName)
 	serviceMonitor.SetNamespace(c.clusterInfo.Namespace)
-	cephv1.GetMonitoringLabels(c.spec.Labels).ApplyToObjectMeta(&serviceMonitor.ObjectMeta)
+	cephv1.GetMonitoringLabels(c.spec.Labels).OverwriteApplyToObjectMeta(&serviceMonitor.ObjectMeta)
 
 	if c.spec.External.Enable {
 		serviceMonitor.Spec.Endpoints[0].Port = controller.ServiceExternalMetricName
@@ -501,7 +501,7 @@ func (c *Cluster) DeployPrometheusRule(name, namespace string) error {
 	if err != nil {
 		return errors.Wrapf(err, "failed to set owner reference to prometheus rule %q", prometheusRule.Name)
 	}
-	cephv1.GetMonitoringLabels(c.spec.Labels).ApplyToObjectMeta(&prometheusRule.ObjectMeta)
+	cephv1.GetMonitoringLabels(c.spec.Labels).OverwriteApplyToObjectMeta(&prometheusRule.ObjectMeta)
 	if _, err := k8sutil.CreateOrUpdatePrometheusRule(prometheusRule); err != nil {
 		return errors.Wrap(err, "prometheus rule could not be deployed")
 	}

pkg/operator/k8sutil/prometheus_test.go

@@ -32,6 +32,7 @@ func TestGetServiceMonitor(t *testing.T) {
 	assert.Nil(t, err)
 	assert.Equal(t, "rook-ceph-mgr", servicemonitor.GetName())
 	assert.Equal(t, "rook-ceph", servicemonitor.GetNamespace())
+	assert.NotNil(t, servicemonitor.GetLabels())
 	assert.NotNil(t, servicemonitor.Spec.NamespaceSelector.MatchNames)
 	assert.NotNil(t, servicemonitor.Spec.Endpoints)
 }