action: add update

[hasbro17]

Added action for update.

[hasbro17]

Test cases for Update:

func main() {
	samplePod := getSamplePod("Pod", "v1", "test-pod", "default")
	fmt.Printf("Pod template: \n%s\n\n", getFormattedJSON(samplePod))

	// Update non-existent pod
	logrus.Infof("Test case 1: Update a non-existent pod")
	pod := samplePod
	// Create pod
	err := action.Update(pod)
	if err != nil {
		logrus.Error(err)
	} else {
		logrus.Errorf("Updated non-existent pod")
		fmt.Printf("Updated Pod: \n%s\n\n", getFormattedJSON(pod))
	}

	// Update pod with correct resource version
	logrus.Infof("Test case 2: Update a pod with correct resource version")
	pod = samplePod
	err = action.Create(pod)
	if err != nil {
		logrus.Errorf("Failed to create pod")
		logrus.Fatal(err)
	} else {
		fmt.Printf("Created Pod: \n%s\n\n", getFormattedJSON(pod))
	}
	// Wait until pod is created and stops changing resource version
	time.Sleep(time.Second * 10)
	// Get the pod
	err = query.Get(pod)
	if err != nil {
		logrus.Errorf("Failed to get pod")
		logrus.Fatal(err)
	} else {
		fmt.Printf("Got Pod: \n%s\n\n", getFormattedJSON(pod))
	}
	// Update the pod's label
	ls := map[string]string{"app": "v1"}
	pod.ObjectMeta.Labels = ls
	err = action.Update(pod)
	if err != nil {
		logrus.Errorf("Failed to update pod's labels with correct resource version(%v)", pod.ResourceVersion)
		logrus.Fatal(err)
	} else {
		fmt.Printf("Updated Pod: \n%s\n\n", getFormattedJSON(pod))
	}

	// Update again with incorrect resource version
        logrus.Infof("Test case 3: Update with incorrect resource version")
	ls = map[string]string{"app": "v2"}
	pod.ObjectMeta.Labels = ls
	pod.ObjectMeta.ResourceVersion = "1"
	err = action.Update(pod)
	if err != nil {
		logrus.Errorf("Failed to update pod's labels with incorrect resource version(%v)", pod.ResourceVersion)
		logrus.Error(err)
	} else {
		logrus.Errorf("Updated pod with incorrect resource version")
		fmt.Printf("Updated Pod: \n%s\n\n", getFormattedJSON(pod))
	}
}

Test logs:

Pod template:
{
    "kind": "Pod",
    "apiVersion": "v1",
    "metadata": {
        "name": "test-pod",
        "namespace": "default",
        "creationTimestamp": null
    },
    "spec": {
        "containers": [
            {
                "name": "mypod",
                "image": "alpine",
                "command": [
                    "/bin/sh",
                    "-c",
                    "while true; do echo running; sleep 100; done"
                ],
                "resources": {}
            }
        ],
        "restartPolicy": "Never"
    },
    "status": {}
}

time="2018-03-26T19:56:37Z" level=info msg="Test case 1: Update a non-existent pod"
time="2018-03-26T19:56:37Z" level=error msg="pods \"test-pod\" not found"
time="2018-03-26T19:56:37Z" level=info msg="Test case 2: Update a pod with correct resource version"
Created Pod:
{
    "kind": "Pod",
    "apiVersion": "v1",
    "metadata": {
        "name": "test-pod",
        "namespace": "default",
        "selfLink": "/api/v1/namespaces/default/pods/test-pod",
        "uid": "cb41b361-312f-11e8-ba9f-0800274106a1",
        "resourceVersion": "185886",
        "creationTimestamp": "2018-03-26T19:56:37Z"
    },
...
}

Got Pod:
{
    "kind": "Pod",
    "apiVersion": "v1",
    "metadata": {
        "name": "test-pod",
        "namespace": "default",
        "selfLink": "/api/v1/namespaces/default/pods/test-pod",
        "uid": "cb41b361-312f-11e8-ba9f-0800274106a1",
        "resourceVersion": "185897",
        "creationTimestamp": "2018-03-26T19:56:37Z"
    },
...
}

Updated Pod:
{
    "kind": "Pod",
    "apiVersion": "v1",
    "metadata": {
        "name": "test-pod",
        "namespace": "default",
        "selfLink": "/api/v1/namespaces/default/pods/test-pod",
        "uid": "cb41b361-312f-11e8-ba9f-0800274106a1",
        "resourceVersion": "185903",
        "creationTimestamp": "2018-03-26T19:56:37Z",
        "labels": {
            "app": "v1"
        }
    },
...
}

time="2018-03-26T19:56:47Z" level=info msg="Test case 3: Update with incorrect resource version"
time="2018-03-26T19:56:47Z" level=error msg="Failed to update pod's labels with incorrect resource version(1)"
time="2018-03-26T19:56:47Z" level=error msg="Operation cannot be fulfilled on pods \"test-pod\": the object has been modified; please apply your changes to the latest version and try again"

[hasbro17]

@fanminshi PTAL.

[fanminshi]

do you know why the created pod's "resourceVersion": "185886" and Got pod's "resourceVersion": "185897" differ for Test case 2?

[hasbro17]

do you know why the created pod's "resourceVersion": "185886" and Got pod's "resourceVersion": "185897" differ for Test case 2?

Yes so depending on the object it can be updated by other components like the scheduler. So when the pod was first created it's status.phase=Pending. When the scheduler schedules it's state will change to status.phase=ContainerCreating and then finally to running.
So it's normal for an object that is created to get updated a lot of times and have it's resource version change.

[fanminshi]

@hasbro17 thanks for the clarification.
LGTM