CLOUDP-60686: Create HaveEqualSpec function and tests (#32)

Author: chatton

go.mod

@@ -16,6 +16,7 @@ require (
 	k8s.io/client-go v12.0.0+incompatible
 	sigs.k8s.io/controller-runtime v0.4.0
 	sigs.k8s.io/yaml v1.1.0
+	github.com/imdario/mergo v0.3.8
 )
 
 // TODO: These replace statements need to be completely removed. These exist as the operator-sdk currently requires

pkg/kube/statefulset/statefulset.go

@@ -1,6 +1,9 @@
 package statefulset
 
 import (
+	"reflect"
+
+	"github.com/imdario/mergo"
 	appsv1 "k8s.io/api/apps/v1"
 	corev1 "k8s.io/api/core/v1"
 )
@@ -78,3 +81,13 @@ func IsReady(sts appsv1.StatefulSet) bool {
 	allReady := replicas == sts.Status.ReadyReplicas
 	return allUpdated && allReady
 }
+
+// HaveEqualSpec accepts a StatefulSet builtSts, and a second existingSts, and compares
+// the Spec of both inputs but only comparing the fields that were specified in builtSts
+func HaveEqualSpec(builtSts appsv1.StatefulSet, existingSts appsv1.StatefulSet) (bool, error) {
+	stsToMerge := *existingSts.DeepCopyObject().(*appsv1.StatefulSet)
+	if err := mergo.Merge(&stsToMerge, builtSts, mergo.WithOverride); err != nil {
+		return false, err
+	}
+	return reflect.DeepEqual(stsToMerge.Spec, existingSts.Spec), nil
+}

pkg/kube/statefulset/statefulset_test.go

@@ -146,7 +146,8 @@ func defaultStatefulSetBuilder() *Builder {
 		SetName(TestName).
 		SetNamespace(TestNamespace).
 		SetServiceName(fmt.Sprintf("%s-svc", TestName)).
-		SetLabels(map[string]string{})
+		SetLabels(map[string]string{}).
+		SetUpdateStrategy(appsv1.RollingUpdateStatefulSetStrategyType)
 }
 
 func podTemplateWithContainers(containers []corev1.Container) corev1.PodTemplateSpec {
@@ -203,3 +204,73 @@ func TestCreateVolumeMountWithMultipleOptions(t *testing.T) {
 	assert.Equal(t, mount.SubPath, "our-subpath")
 	assert.True(t, mount.ReadOnly)
 }
+
+func TestHaveEqualSpec(t *testing.T) {
+	t.Run("Identical StatefulSet", func(t *testing.T) {
+		builtSts, _ := defaultStatefulSetBuilder().Build()
+		existingSts, _ := defaultStatefulSetBuilder().Build()
+		areEqual, err := HaveEqualSpec(builtSts, existingSts)
+		assert.NoError(t, err)
+		assert.True(t, areEqual, "When both stateful sets are identical, these should be considered equivalent")
+	})
+	t.Run("Built StatefulSet is different from existing StatefulSet", func(t *testing.T) {
+		builtSts, _ := defaultStatefulSetBuilder().SetUpdateStrategy(appsv1.OnDeleteStatefulSetStrategyType).Build()
+		existingSts, _ := defaultStatefulSetBuilder().Build()
+		areEqual, err := HaveEqualSpec(builtSts, existingSts)
+		assert.NoError(t, err)
+		assert.False(t, areEqual, "We have specified a field that is different from the existing StatefulSet, so these should be considered different")
+	})
+	t.Run("Existing StatefulSet has values we don't specify", func(t *testing.T) {
+		builtSts, _ := defaultStatefulSetBuilder().Build()
+		existingSts, _ := defaultStatefulSetBuilder().Build()
+		revHistoryList := int32(30)
+		existingSts.Spec.RevisionHistoryLimit = &revHistoryList
+
+		areEqual, err := HaveEqualSpec(builtSts, existingSts)
+		assert.NoError(t, err)
+		assert.True(t, areEqual, "Specs should be considered equal even though the existing StatefulSet has fields we are not interested in")
+	})
+
+	t.Run("Metadata differences", func(t *testing.T) {
+		builtSts, _ := defaultStatefulSetBuilder().SetName("different-name").Build()
+		existingSts, _ := defaultStatefulSetBuilder().Build()
+		areEqual, err := HaveEqualSpec(builtSts, existingSts)
+		assert.NoError(t, err)
+		assert.True(t, areEqual, "Metadata differences should not be considered, we are just looking at spec")
+	})
+
+	t.Run("Change to PodSpecTemplate", func(t *testing.T) {
+		builtSts, _ := defaultStatefulSetBuilder().Build()
+		existingSts, _ := defaultStatefulSetBuilder().Build()
+		t.Run("Same Container added", func(t *testing.T) {
+			builtSts.Spec.Template.Spec.Containers = []corev1.Container{{Name: "container-1"}}
+			existingSts.Spec.Template.Spec.Containers = []corev1.Container{{Name: "container-1"}}
+			areEqual, err := HaveEqualSpec(builtSts, existingSts)
+			assert.NoError(t, err)
+			assert.True(t, areEqual, "Having the same container should be equal")
+		})
+
+		t.Run("Existing StatefulSet has init containers", func(t *testing.T) {
+			builtSts.Spec.Template.Spec.Containers = []corev1.Container{{Name: "container-1"}}
+			existingSts.Spec.Template.Spec.Containers = []corev1.Container{{Name: "container-1"}}
+			existingSts.Spec.Template.Spec.InitContainers = []corev1.Container{{Name: "container-1-init"}}
+			areEqual, err := HaveEqualSpec(builtSts, existingSts)
+			assert.NoError(t, err)
+			assert.True(t, areEqual, "The existing StatefulSet has a field we have not touched in the spec (initContainers), this should be ignored in spec comparison")
+		})
+		t.Run("Different Container added", func(t *testing.T) {
+			builtSts.Spec.Template.Spec.Containers = []corev1.Container{{Name: "container-2"}}
+			existingSts.Spec.Template.Spec.Containers = []corev1.Container{{Name: "container-3"}}
+			areEqual, err := HaveEqualSpec(builtSts, existingSts)
+			assert.NoError(t, err)
+			assert.False(t, areEqual, "Metadata differences should not be considered, we are just looking at spec")
+		})
+		t.Run("Image Change", func(t *testing.T) {
+			builtSts.Spec.Template.Spec.Containers = []corev1.Container{{Name: "container-1", Image: "image-1"}}
+			existingSts.Spec.Template.Spec.Containers = []corev1.Container{{Name: "container-1", Image: "image-2"}}
+			areEqual, err := HaveEqualSpec(builtSts, existingSts)
+			assert.NoError(t, err)
+			assert.False(t, areEqual, "A single different field in an element in a list should result in the specs being different")
+		})
+	})
+}