Merge pull request #63844 from tossmilestone/add-statefulset-strategy-desc

Automatic merge from submit-queue (batch tested with PRs 63871, 63927, 63966, 63957, 63844). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Add strategy description for 'kubectl describe sts' command

**What this PR does / why we need it**:
To display `UpdateStrategyType` and `RollingUpdateStrategy` information when execute `kubectl describe sts` command, the output likes:
```
Name:               web
Namespace:          default
CreationTimestamp:  Thu, 17 May 2018 10:21:19 +0800
Selector:           app=nginx
Labels:             app=nginx
Annotations:        <none>
Replicas:           3 desired | 1 total
Update Strategy:    RollingUpdate
  Partition:        2
Pods Status:        0 Running / 1 Waiting / 0 Succeeded / 0 Failed
Pod Template:
  Labels:  app=nginx
  Containers:
   nginx:
    Image:        k8s.gcr.io/nginx-slim:0.8
    Port:         80/TCP
    Host Port:    0/TCP
    Environment:  <none>
    Mounts:
      /usr/share/nginx/html from www (rw)
  Volumes:  <none>
Volume Claims:
  Name:          www
  StorageClass:  my-storage-class
  Labels:        <none>
  Annotations:   <none>
  Capacity:      1Gi
  Access Modes:  [ReadWriteOnce]
Events:
  Type    Reason            Age   From                    Message
  ----    ------            ----  ----                    -------
  Normal  SuccessfulCreate  10s   statefulset-controller  create Pod web-0 in StatefulSet web successful
```

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes None

**Special notes for your reviewer**:

**Release note**:

```release-note
Add 'UpdateStrategyType' and 'RollingUpdateStrategy' to 'kubectl describe sts' command output.
```

pkg/printers/internalversion/describe.go

@@ -2764,6 +2764,14 @@ func describeStatefulSet(ps *apps.StatefulSet, selector labels.Selector, events
 		printLabelsMultiline(w, "Labels", ps.Labels)
 		printAnnotationsMultiline(w, "Annotations", ps.Annotations)
 		w.Write(LEVEL_0, "Replicas:\t%d desired | %d total\n", ps.Spec.Replicas, ps.Status.Replicas)
+		w.Write(LEVEL_0, "Update Strategy:\t%s\n", ps.Spec.UpdateStrategy.Type)
+		if ps.Spec.UpdateStrategy.RollingUpdate != nil {
+			ru := ps.Spec.UpdateStrategy.RollingUpdate
+			if ru.Partition != 0 {
+				w.Write(LEVEL_1, "Partition:\t%d\n", ru.Partition)
+			}
+		}
+
 		w.Write(LEVEL_0, "Pods Status:\t%d Running / %d Waiting / %d Succeeded / %d Failed\n", running, waiting, succeeded, failed)
 		DescribePodTemplate(&ps.Spec.Template, w)
 		describeVolumeClaimTemplates(ps.Spec.VolumeClaimTemplates, w)

pkg/printers/internalversion/describe_test.go

@@ -33,6 +33,7 @@ import (
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/util/intstr"
 	versionedfake "k8s.io/client-go/kubernetes/fake"
+	"k8s.io/kubernetes/pkg/apis/apps"
 	"k8s.io/kubernetes/pkg/apis/autoscaling"
 	api "k8s.io/kubernetes/pkg/apis/core"
 	"k8s.io/kubernetes/pkg/apis/extensions"
@@ -2526,6 +2527,46 @@ func TestDescribeNode(t *testing.T) {
 
 }
 
+func TestDescribeStatefulSet(t *testing.T) {
+	fake := fake.NewSimpleClientset(&apps.StatefulSet{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:      "bar",
+			Namespace: "foo",
+		},
+		Spec: apps.StatefulSetSpec{
+			Replicas: 1,
+			Selector: &metav1.LabelSelector{},
+			Template: api.PodTemplateSpec{
+				Spec: api.PodSpec{
+					Containers: []api.Container{
+						{Image: "mytest-image:latest"},
+					},
+				},
+			},
+			UpdateStrategy: apps.StatefulSetUpdateStrategy{
+				Type: apps.RollingUpdateStatefulSetStrategyType,
+				RollingUpdate: &apps.RollingUpdateStatefulSetStrategy{
+					Partition: 2,
+				},
+			},
+		},
+	})
+	d := StatefulSetDescriber{fake}
+	out, err := d.Describe("foo", "bar", printers.DescriberSettings{ShowEvents: true})
+	if err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+	expectedOutputs := []string{
+		"bar", "foo", "Containers:", "mytest-image:latest", "Update Strategy", "RollingUpdate", "Partition",
+	}
+	for _, o := range expectedOutputs {
+		if !strings.Contains(out, o) {
+			t.Errorf("unexpected out: %s", out)
+			break
+		}
+	}
+}
+
 // boolPtr returns a pointer to a bool
 func boolPtr(b bool) *bool {
 	o := b