better apply --prune

[Liujingfang1]

Is this a BUG REPORT or FEATURE REQUEST? (choose one):
feature request

While kubectl apply is widely used in different workflows, users need kubectl apply --prune to sync the resources on cluster with configuration saved in files, directories or repos.

Currently kubectl apply --prune is still in Alpha. It prunes objects by matching labels. Users must be really careful when they use this command so that they don't delete objects unintentionally. There are a list of issues with current pruning behavior: kubernetes/kubernetes#69879, kubernetes/kubernetes#68400, kubernetes/kubernetes#66430, kubernetes/kubernetes#40635, #555

We need better kubectl apply --prune so that it will meet the users' requirement of syncing resources and get rid of current issues.

[Liujingfang1]

@pwittrock

[crimsonfaith91]

@Liujingfang1
We definitely have to make kubectl apply --prune better. Alternatively, as @seans3 pointed out during by-person sync, we should also support dry-run of the command too.

Perhaps we can make kubectl apply --prune a 2-step command? The first step is to show all resource changes (dry-run), and the second step is for users to input y/n (performing real changes).

[rdxmb]

and the second step is for users to input y/n (performing real changes).

This is good for starting with prune. However, for running --prune in CI there has to be a way to run it non-interactively (kubernetes/kubernetes#74414)

[fejta-bot]

Issues go stale after 90d of inactivity.
Mark the issue as fresh with /remove-lifecycle stale.
Stale issues rot after an additional 30d of inactivity and eventually close.

If this issue is safe to close now please do so with /close.

Send feedback to sig-testing, kubernetes/test-infra and/or fejta.
/lifecycle stale

[rdxmb]

/remove-lifecycle stale

[fejta-bot]

Issues go stale after 90d of inactivity.
Mark the issue as fresh with /remove-lifecycle stale.
Stale issues rot after an additional 30d of inactivity and eventually close.

If this issue is safe to close now please do so with /close.

Send feedback to sig-testing, kubernetes/test-infra and/or fejta.
/lifecycle stale

[tbarrella]

/remove-lifecycle stale

[fejta-bot]

Issues go stale after 90d of inactivity.
Mark the issue as fresh with /remove-lifecycle stale.
Stale issues rot after an additional 30d of inactivity and eventually close.

If this issue is safe to close now please do so with /close.

Send feedback to sig-testing, kubernetes/test-infra and/or fejta.
/lifecycle stale