Fix redefine flag

[filintod]

Description

This PR add something similar to kubernetes-sigs/controller-runtime#1999 to avoid redefined kubeconfig flag issues when using this library plus others that might already have kubeconfig as a flag.

Issue reference

We strive to have all PR being opened based on an issue, where the problem or feature have been discussed prior to implementation.

Please reference the issue this PR will close: #2993

Checklist

Please make sure you've completed the relevant tasks for this PR, out of the following list:

• Code compiles correctly
• Created/updated tests
• Extended the documentation / Created issue in the https://github.com/dapr/docs/ repo: dapr/docs#[issue number]

[ItalyPaleAle]

Although this PR LGTM, I was not aware of this code and this behavior. It does seem odd that we're defining CLI flags in components-contrib. This seems anti-pattern?

[filintod]

It does seem strange maybe to ease tests but don't know the original use case

[daixiang0]

It does seem strange maybe to ease tests but don't know the original use case

Do we really register it in the CLI?

[ItalyPaleAle]

Looks like it is getting registered. Running daprd --help:

  -kubeconfig string
    	(optional) absolute path to the kubeconfig file (default "/Users/alessandro/.kube/config")

I think this needs to change. We should allow setting the kubeconfig file using the metadata for each component.

@filintod can you change that please?

[ItalyPaleAle]

Let's refactor this to avoid adding CLI flags to daprd

[filintod]

I can follow as how it is done in dapr https://github.com/dapr/dapr/blob/master/utils/utils.go#L50

with a custom kubeconfig env var KUBE_CONFIG

wdty?

[ItalyPaleAle]

@filintod that method looks like is being used by Dapr control plane services only (operator, injector, sentry), and not by daprd.

I would prefer the Kubeconfig path to be a metadata option in all Kubernetes components. This is the pattern we use to configure all components.

[filintod]

thanks, sorry I forgot about this.

[ItalyPaleAle]

thanks, sorry I forgot about this.

No worries! It became a bit more of a pressure because of dapr/dapr#6766

Do the changes look good to you? Mind doing a quick review?
Essentially I needed to remove the use of flag.Parse because it could cause a panic if the entire app doesn't use the global flag definition.

I plan on doing the 2nd part, which is allowing setting kubeconfig path in components' metadata, in a separate PR.

[ItalyPaleAle]

See #3060 for part 2