Scaling StatefulSet filtered using label selectors

Is your enhancement related to a problem? Please describe

I’m trying scale a StatefulSet by selecting it using its labels. For example, kubectl allows following:

$ kubectl scale statefulset -l release=yb,app.kubernetes.io/name=yb-tserver --replicas=4
statefulset.apps/yb-yugabyte-yb-tserver scaled

But when we filter StatefulSets with label selectors, the scale() method is not there.

Describe the solution you’d like

I’m thinking of something similar like this:

client
    .apps()
    .statefulSets()
    .withLabel("release", "yb")
    .withLabel(appLabel, "yb-tserver")
    .scale(4);

Describe alternatives you’ve considered

So far I have tried using list(), and then getting the first StatefulSet out of it. But when I tried to load the StatefulSet into client, the scale() method was not present. So, I had to use the metadata.name.

StatefulSet sts =
    client
	.apps()
	.statefulSets()
	.withLabel("release", "yb")
	.withLabel(appLabel, "yb-tserver")
	.list()
	.getItems()
	.get(0);

// This was not possible (should I create a separate issue for this?)
client.resource(sts).scale(4);

// I had to do this instead
client
    .apps()
    .statefulSets()
    .withName(sts.getMetadata().getName())
    .scale(4);

Additional context

When kubectl finds multiple StatefulSets filtered the label selectors, it just scales all of them.

$ kubectl scale statefulset -l release=yb --replicas=4
statefulset.apps/yb-yugabyte-yb-master scaled
statefulset.apps/yb-yugabyte-yb-tserver scaled

[bhavin192]

That’s great, thanks! I have been away for a while, I will send PR for docs/example entry next week. With my PR we can close this issue.

[shawkins]

a resources method was added with #3973

client.apps().statefulSets()
  .withLabel("release", "yb")
  .withLabel(appLabel, "yb-tserver")
  .resources()
  .forEach(s -> s.scale(4));