Initial implementation of Helm Renderer

[tete17]

Related:#1937

Description
This PR should add Render capabilities to the Helm deployer.
I have added support for the following feature:

• valuesFiles
• setValueTemplates
• values
• Namespaced charts

I hope this is enough, If I have missed some that are consider a must please let me know. I have also tried having a good support between Helm v3 and v2.

User facing changes (remove if N/A)

The only user facing change (except the obvious addition of skaffold render for helm, can bee seen here.

I have changed this behaviour because it was assuming all members of the values map were supposed to be images built by skaffold. This is use to make skaffold replace the images by the combination of the image:tag in the manifest.

I have modified so it only looks for the appropiate images and doesn't fail if you add something like

values: 
   image: "skaffold-helm"
   replicas: 3

This lead me to modify certain unit tests accordingly. I am not entirely sure about this change I am by no means and expert in helm so feedback is highly welcomed.

It is also my first contribution to a go project so please be gentle 😄. I hope I followed best practice I have a feeling I am duplicating some code so please let me know if someone else also has that feeling.

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[tete17]

@googlebot I signed it!

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[codecov]

Codecov Report

Merging #3929 into master will increase coverage by 0.02%.
The diff coverage is 77.55%.

Impacted Files	Coverage Δ
pkg/skaffold/deploy/helm.go	80.27% <77.55%> (+0.02%)	⬆️

[googlebot]

We found a Contributor License Agreement for you (the sender of this pull request), but were unable to find agreements for all the commit author(s) or Co-authors. If you authored these, maybe you used a different email address in the git commits than was used to sign the CLA (login here to double check)? If these were authored by someone else, then they will need to sign a CLA as well, and confirm that they're okay with these being contributed to Google.
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[abh]

At a glance this also fixes a bug where the namespace specified with skaffold -n ... isn't actually used. Yay @tete17 :-)

[tete17]

I rebased the branch to the latest master

[tete17]

I rebased once more.

Is there anything I am missing to get a review? I don't want this to be forgotten, maybe I have done something wrong but I can't seem to find anythin on DEVELOPMENT.md nor CONTRIBUTING.md

[nkubala]

@tete17 thanks so much for the contribution, and sorry for the late review! I left a few comments but this is actually looking pretty good. it would be great to get an integration test for this as well - would you mind adding a quick test case or two to pkg/integration/render_test.go? you can model it after the existing tests there for the other renderers.

[tete17]

@nkubala Thank you very much for the review.

I hope I didn't gave the impression of desperate 😆 by asking for a review.

I went ahead and I think addressed all of your comment, as well as rebasing to the latest master.

Took me a bit of time but I also added some integrations tests. Let me know if you think we can add more content to them.

[nkubala]

@tete17 this looks great! see my comment about the change to how we process the helm values from the skaffold.yaml, I think we should move that to a separate PR. once you take that out this LGTM and I'll merge it!

[tete17]

I used this chance to rebase once more and cleanup the commits to make a nice git history.

Take it from here @nkubala

[tete17]

@nkubala can you review?

[tete17]

I went ahead and rebased once more to fix the conflicts introduced in #4169

[nkubala]

LGTM, thanks so much for all your hard work getting this one in @tete17!

[tete17]

My pleasure thanks to @nkubala & @tstromberg for the constant reviews.

I also wonder is we could use this chance to also move skaffold render out of alpha and into beta since all deployers are supported now?