Support kustomize "extended" patches. #2909

[grumps]

Relates to in case of new feature, this should point to issue/(s) which describes the feature

Fixes #2909

Should merge before :n/a

Should merge after : n/a

Description

implement #2909: support extended kustomize patches

User facing changes

n/a

Before

n/a
After
n/a
Next PRs.
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-->

Submitter Checklist

These are the criteria that every PR should meet, please check them off as you
review them:

• [x ] Includes unit tests
• [n/a ] Mentions any output changes.
• [n/a ] Adds documentation as needed: user docs, YAML reference, CLI reference.
• [ n/a] Adds integration tests if needed.

Reviewer Notes

• The code flow looks good.
• Unit test added.
• User facing changes look good.

Release Notes

Examples of user facing changes:
- Skaffold config changes like
  e.g. "Add buildArgs to `Kustomize` deployer skaffold config."
- Bug fixes
  e.g. "Improve skaffold init behavior when tags are used in manifests"
- Any changes in skaffold behavior
  e.g. "Artifact caching is turned on by default."

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[codecov]

Codecov Report

Merging #3663 into master will increase coverage by 0.01%.
The diff coverage is 86.66%.

Impacted Files	Coverage Δ
pkg/skaffold/deploy/kustomize.go	72.5% <86.66%> (+0.87%)	⬆️

[grumps]

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[tejal29]

LGTM.

[tejal29]

Restarted the failed window unit test.

[grumps]

@tejal29 looks like the windows test passed this time!

[nkubala]

shouldn't we try and stay backwards compatible with older kustomization.yamls? this will break existing users using the older format.

[nkubala]

should we be checking an error here?

[grumps]

@nkubala, I'm relatively new to Golang so .... I didn't do the err check here because it will error if its a string and is part of the old API. Now that I'm thinking about it now maybe I could do something like (psuedo code)

err = unmarshall
if pp.path and pp.patch is nil and if err:
   err2 := unmarshal_to_string()
if err and err2:
   log error

Thoughts?

[tejal29]

i think this change is backward compatible.

	if pp.Path == "" && pp.Patch == "" {

should imply

if err != nil {

to make it explicitly you could

pp := &patchPath{}
if err := unmarshal(&pp); err != nil{
                var oldPathString string
		if err := unmarshal(&oldPathString); err != nil {
			return err
		}

		warnings.Printf("list of file paths deprecated: see https://github.com/kubernetes-sigs/kustomize/blob/master/docs/plugins/builtins.md#patchtransformer")
		pp.Path = oldPathString
}

[grumps]

Implemented "explicit".