Adding a package to contain common sidecar flags

[DerekFrank]

What type of PR is this?

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/kind api-change
/kind bug

/kind cleanup

/kind design
/kind documentation
/kind failing-test
/kind feature
/kind flake

What this PR does / why we need it:

Following a discussion in the #csi channel of the k8s slack, folks generally support moving common sidecar flags into a shared package.

Example sidecar flags

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

[k8s-ci-robot]

Hi @DerekFrank. Thanks for your PR.

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[mauriciopoppe]

Please add a link to the conversation thread in Slack in the PR description.

Thanks for considering the monorepo sidecar design as an example on how to extract the flags! Hey Ge, could you please check that these params match your analysis in https://docs.google.com/document/d/1AKqJeAlBL8PkH8D9zABCZ82Bk1N46EygKPvVh5p4-qU/edit? cc @ConnorJC3.

/cc @mowangdk
/ok-to-test

[DerekFrank]

I'm honestly not sure if we want to move this into this function as well, I did it because we need access to mux for le.PrepareHealthCheck(mux, leaderelection.DefaultHealthCheckTimeout) and as far as I can tell nothing else in the sidecar's main.go files reference the mux.

[jsafrane]

Yes, it looks odd here. Get the mux from the callers, as an argument.

[jsafrane]

Yes, it looks odd here. Get the mux from the callers, as an argument.

[DerekFrank]

Made sidecar PRs as well for comparison:

• refactor: use common sidecar flags functionality external-attacher#684
• Use central flags external-provisioner#1421
• refactor: use common sidecar flags functionality external-health-monitor#341
• refactor: use common sidecar flags functionality external-snapshotter#1336
• refactor: use common sidecar flags functionality external-resizer#528

The other sidecars don't have leader election, unless I missed one!

[mowangdk]

/lgtm

Thank you for your PR. This will also help the CSI Sidecar AIO project~

[DerekFrank]

@jsafrane Any other feedback?

[jsafrane]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: DerekFrank, jsafrane

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