✨ Make external plugin path configurable

[Eileen-Yu]

Description

1. Introduce the usage of env variable KB_PLUGINS_PATH to define a customized path to store external plugins.
2. Add corresponding unit tests

Sample

~/programming/temp/my-external-plugins  
❯ tree .
.
└── sampleexternalplugin
   └── v1
      └── sampleexternalplugin

~/programming/temp/my-external-plugins                                                                                                                                                
❯ KB_PLUGIN_PATH="/Users/eileen/programming/temp/my-external-plugins" \
  kubebuilder init --plugins=sampleexternalplugin/v1

Motivation

Make the external plugin path configurable so that users can easily manage their external plugins.

[k8s-ci-robot]

Hi @Eileen-Yu. Thanks for your PR.

I'm waiting for a kubernetes-sigs 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.

[everettraven]

Overall really great work! My biggest request is to take another pass at the tests implementation and try to break them down into individual smaller tests

[camilamacedo86]

/ok-to-test

[camilamacedo86]

HI @Eileen-Yu,

Can we cover a little more with the tests:

coverage/coveralls — Coverage decreased (-0.1%) to 83.135%

It decrease here: https://coveralls.io/builds/60550613/source?filename=pkg%2Fcli%2Foptions.go

[everettraven]

Overall looks good and is a step in the right direction. What I would like to see is for the tests for the $XDGHOME and $HOME environment variables to be distinct tests (so no if ... else block to perform special test logic)

[camilamacedo86]

Great work 🥇

Just a nit:
Otherwise, /lgtm

Is KB_PLUGINS_PATH the best name for the env var?
What about EXTERNAL_PLUGINS_PATH only?
I mean without kubebuilder since other projects can export Kubebuilder and use it as lib to create their own tools.

c/c @everettraven @rashmigottipati

[everettraven]

Overall looks great - I just have some more comments on the tests

[everettraven]

Looks good to me! Great work @Eileen-Yu !

/lgtm

[camilamacedo86]

Terrific work 🥇

/approved

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: camilamacedo86, Eileen-Yu, everettraven

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 [camilamacedo86]

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