Profile replacement does not always work

[briandealwis]

Our docs say:

Once a profile is activated, the specified build, test and deploy configuration in it will replace the build, test and deploy sections declared in the main section of skaffold.yaml.

This implies that a pipeline like the following:

build:
  artifacts:
  - image: example

profiles:
- name: example
  build: {}

applying the example profile should replace the build: sections, such that there are no artifacts to build. But it does not.

We should either fix this, or change the documentation to reflect the reality that we merge overlay the paths found in the profile:

skaffold/pkg/skaffold/schema/profiles.go

Lines 206 to 210 in d9b397e

	for i := 0; i < profileT.NumField(); i++ {
	name := profileT.Field(i).Name
	merged := overlayProfileField(name, configV.FieldByName(name).Interface(), profileV.FieldByName(name).Interface())
	mergedV.FieldByName(name).Set(reflect.ValueOf(merged))
	}

[briantopping]

The doc text now says the following:

Once a profile is activated, the specified build, test and deploy configuration in it will be laid onto, but won’t completely replace, the build, test and deploy sections declared in the main section of skaffold.yaml.

If the content in the profile was once "overlaid", it is now replacing. So the documentation has been changed to match this behavior as when this issue was written, but the behavior has seemingly changed again.

@aaron-prindle offered to try using a patch in this slack convo, that worked.

I can't advocate which way it ought to work due to lack of experience with Skaffold, but my preference would be for a merge instead of a replacement. As I said in that OP:

I could duplicate everything down (to the profile), but then it’s not DRY. I could create the content as a YAML anchor, but that’s wonky.