Fix and improve sync samples

[dgageot]

• Fixed the sync configuration on hot-reload sample
• Fix all samples so that they actually work
• Convert pods into deployments. Now that port forwarding is not activated, deployments need to be exposed with a service
• Simplify the skaffold.yaml files with regards to deploy config.
• Improve the Dockerfiles (caching, smaller and more recent base images...)

[codecov-io]

Codecov Report

Merging #2131 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #2131   +/-   ##
=======================================
  Coverage   56.33%   56.33%           
=======================================
  Files         180      180           
  Lines        7840     7840           
=======================================
  Hits         4417     4417           
  Misses       3002     3002           
  Partials      421      421

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[dgageot]

@corneliusweig Could you take a look at those fixes? Thanks!

[corneliusweig]

oops.. this should not have happened (@.myself). The reason why it could is that react-reload has no test-case in run_test.go.

[corneliusweig]

Suggested change

	COPY src .
	COPY src src/

Otherwise docker flattens the directory at the destination. And in the package.json the main file is src/index.js. I think it only works by accident, because node looks for index.js in the root folder if the entrypoint is not found.

The other examples are fine, because they use COPY . .

[dgageot]

I think the idea was to flatten the directory. in the skaffold.yaml, sync is configured to strip the src/ prefix.
I'll fix the package.json though.

[corneliusweig]

Thanks for this examples face-lift. Looks very nice overall. There's one nit and the following bigger issue:

All these examples are not run during integration tests (run_test.go):

examples/compose
examples/helm-deployment-dependencies
examples/hot-reload
examples/jib
examples/jib-multimodule
examples/kustomize
examples/react-reload

At least for react-reload I can say that I simply didn't know that a test-case needed to be added. Should we do that? Could also be another PR, because this one is already quite large.

[dgageot]

Good point. I'll push a PR to test more samples (not sure it's easy to test them all) after this PR is merged.

[corneliusweig]

@dgageot LGTM

[nkubala]

nice, thanks @dgageot