Add completion for kubectl set image

[ah8ad3]

What type of PR is this?

/kind feature

What this PR does / why we need it:

Adds completion function for kubectl set image

Which issue(s) this PR fixes:

Fixes kubernetes/kubectl#1585

Special notes for your reviewer:

As we discussed in meeting this code here is just a sample on what is my approach to fix and suggestions about fixing this problem for other commands as well.

Current code act like this:
kubectl set image TAB:
cronjobs/ daemonsets/ deployments/ pods/ replicasets/ replicationcontrollers/ statefulsets/

and
kubectl set image pods/nginx-565b7446dd-dtm55 TAB:
kubectl set image pods/nginx-565b7446dd-dtm55 nginx=

Also if pod has few containers it will remove suggestions based on selected containers in argument.

This code is just the sample of how to fix it, we should discuss about it and what is our approach in future to add more completions, should we refactor the completion's functions or do it this way.
/cc @mpuckett159

Does this PR introduce a user-facing change?

Adds completion for `kubectl set image`.

[k8s-ci-robot]

Hi @ah8ad3. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[ardaguclu]

/ok-to-test

[ah8ad3]

Thanks for review, two of comments are addressed in last commit. For using restclientgetter i'm waiting for response #124592 (comment). PTAL @ardaguclu

[ah8ad3]

Thanks for reviews, comments addressed. PTAL @ardaguclu

Maybe later we can raise another issue to add support for containers in completion.

[ardaguclu]

Thanks for reviews, comments addressed. PTAL @ardaguclu

Maybe later we can raise another issue to add support for containers in completion.

That is good idea. Thanks for the work @ah8ad3

/triage accepted
/priority backlog
/approve
/lgtm

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 7403bddf19e94319ace9640f13977a85b086489c

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ah8ad3, ardaguclu

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• staging/src/k8s.io/kubectl/OWNERS [ardaguclu]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment