Add watch_stop to DynamicClient

[hedinasr]

What type of PR is this?

/kind feature

What this PR does / why we need it:

This PR introduce a way to close a watching stream.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

NONE

[k8s-ci-robot]

Thanks for your pull request. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

📝 Please follow instructions at https://git.k8s.io/community/CLA.md#the-contributor-license-agreement to sign the CLA.

It may take a couple minutes for the CLA signature to be fully registered; after that, please reply here with a new comment and we'll verify. Thanks.

---

• If you've already signed a CLA, it's possible we don't have your GitHub username or you're using a different email address. Check your existing CLA data and verify that your email is set on your git commits.
• If you signed the CLA as a corporation, please sign in with your organization's credentials at https://identity.linuxfoundation.org/projects/cncf to be authorized.
• If you have done the above and are still having issues with the CLA being reported as unsigned, please log a ticket with the Linux Foundation Helpdesk: https://support.linuxfoundation.org/
• Should you encounter any issues with the Linux Foundation Helpdesk, send a message to the backup e-mail support address at: [email protected]

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. I understand the commands that are listed here.

[k8s-ci-robot]

Welcome @hedinasr!

It looks like this is your first PR to kubernetes-client/python-base 🎉. Please refer to our pull request process documentation to help your PR have a smooth ride to approval.

You will be prompted by a bot to use commands during the review process. Do not be afraid to follow the prompts! It is okay to experiment. Here is the bot commands documentation.

You can also check if kubernetes-client/python-base has its own contribution guidelines.

You may want to refer to our testing guide if you run into trouble with your tests not passing.

If you are having difficulty getting your pull request seen, please follow the recommended escalation practices. Also, for tips and tricks in the contribution process you may want to read the Kubernetes contributor cheat sheet. We want to make sure your contribution gets all the attention it needs!

Thank you, and welcome to Kubernetes. 😃

[hedinasr]

Thanks for your pull request. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

📝 Please follow instructions at https://git.k8s.io/community/CLA.md#the-contributor-license-agreement to sign the CLA.

It may take a couple minutes for the CLA signature to be fully registered; after that, please reply here with a new comment and we'll verify. Thanks.

• If you've already signed a CLA, it's possible we don't have your GitHub username or you're using a different email address. Check your existing CLA data and verify that your email is set on your git commits.
• If you signed the CLA as a corporation, please sign in with your organization's credentials at https://identity.linuxfoundation.org/projects/cncf to be authorized.
• If you have done the above and are still having issues with the CLA being reported as unsigned, please log a ticket with the Linux Foundation Helpdesk: https://support.linuxfoundation.org/
• Should you encounter any issues with the Linux Foundation Helpdesk, send a message to the backup e-mail support address at: [email protected]

Check CLA

[roycaihw]

/assign @fabianvf

[fabianvf]

I think you can create multiple simultaneous watch invocations on the same client, but in this case doing that will mean that subsequent invocations before the initial watch is closed will overwrite this client-global variable. I think we'd need to find a way to scope the stop function the user can access to the specific watch that they need to stop.

[hedinasr]

What about adding a watcher optional parameter ? This way, the user can instantiate his own Watch object, and call the stop function from that object. An example:

def watch(self, resource, namespace=None, name=None, label_selector=None, field_selector=None, resource_version=None, timeout=None, watcher=None):
    if not watcher: watcher = watch.Watch()
    # no changes here

client = DynamicClient(k8s_client)
watcher = watch.Watch()
v1_pods = client.resources.get(api_version='v1', kind='Pod')

for e in v1_pods.watch(resource_version=0, namespace=default, timeout=5, watcher=watcher):
    print(e['type'])
    print(e['object'].metadata)
    watcher.stop()

What do you think ?

[fabianvf]

This approach seems sane to me, I can't really think of anything better

[fabianvf]

is it typical to catch KeyboardInterrupts in a library like this? I would expect that to be handled by the caller. That being said, should we be stopping the watcher on any exception? Not sure if we gain anything from leaving it open if we're exiting this function anyway

[hedinasr]

I totally agree with you on this one, this should be handled by the caller. Anyway, there is a finally clause in the Watch.stream function that cleans up the connection if anything bad happened, so my worries here are not relevant.

[fabianvf]

/lgtm

[fabianvf]

/assign @yliaog

[yliaog]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: fabianvf, hedinasr, yliaog

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:

• OWNERS [yliaog]

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