Add optional support for helm diff

[gravesm]

SUMMARY

There are some cases where the existing module has difficulty
determining if an upgrade would result in changes. This can particularly
be a problem when changes are made to a local chart.

This adds optional support for helm diff. If the plugin is present it
will be used. Otherwise, the default implementation will be used and a
warning will be issued. One caveat: helm diff does not currently support
using a repo url, so the default implementation will be used in this
case, as well.

Closes #248

ISSUE TYPE

• Feature Pull Request

COMPONENT NAME

helm

ADDITIONAL INFORMATION

Several of our existing tests break when helm diff is installed. This is because our local path test charts don't actually contain any resources so nothing changes when we do any upgrade. Changing the appVersion or adding new values won't make a difference. I have added a simple ConfigMap to our test charts so that when an upgrade happens it will actually change something. This is the reason for all the changes to the existing tests.

[codecov]

Codecov Report

Merging #355 (5a35725) into main (5a5ed79) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #355   +/-   ##
=======================================
  Coverage   36.80%   36.80%           
=======================================
  Files           3        3           
  Lines         758      758           
  Branches      148      148           
=======================================
  Hits          279      279           
  Misses        430      430           
  Partials       49       49           

---

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[Akasurde]

ERROR: plugins/modules/helm.py:412:14: blacklisted-name: Black listed name "_"

[gravesm]

@Akasurde yes, that one I'm not worried about. It's an easy fix. The bigger problem is I don't know how to address the yamllint errors. Fixing those errors will break the templates for go.

[Akasurde]

Oh yes. I didn't see that. I will check that now.

[gravesm]

@Akasurde I think I sorted out the linting issues. If there's a better way to do this, I'm happy to be educated. I wish we could ignore a directory, but that doesn't seem possible.

[Akasurde]

@gravesm We can disable yamllint with several ways.

1. Disable directory - https://yamllint.readthedocs.io/en/stable/configuration.html#ignoring-paths
2. Disable single line - https://yamllint.readthedocs.io/en/stable/disable_with_comments.html#disabling-checks-for-a-specific-line
3. Disable single file - https://yamllint.readthedocs.io/en/stable/disable_with_comments.html#disabling-checks-for-all-or-part-of-the-file

I am OK with current configuration as well since I don't see chart files changing any time soon.

[Akasurde]

LGTM

[github-actions]

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