Feature: Added force-fetch functionality (#858)

[MatteoVoges]

Fixes issue: #858

Proposed Changes

• Added a option to have a force_fetch-property in your external dependencies.
  If force_fetch is set to true, this dependency will always get fetched and overwrite existing files (force-fetch).

• Renamed --force-flag to --force-fetch, so you have to run

  • $ kapitan compile --fetch to fetch (existing files won't get overwritten) or
  • $ kapitan compile --force-fetch to fetch the dependencies and overwrite existing files.

If the property is false or not given, the default-behavior of the fetch-functionality doesn't change.
Also the behavior of --fetch and (now:)--force-fetch doesn't change either.

NOTE: Using --force will still work with its default behavior, but is now a deprecated flag and will be removed soon.

Documentation and testing

Updated flag-name in the docs and in the tests.

[MatteoVoges]

Hi @ramaro @ademariag ,

I applied the changes we discussed, so the PR is ready to review.

But there is one more thing I noticed:
I don't like the way the code for the fetch-functionality is structured. There are multiple if-statements checking the same, and its hard to follow and unterstand the code in general. I would suggest something like this:

[...]
# getting the flag values
if fetch:
    # fetch inventories
    # fetch dependencies
else:
    # fetch targets with fetch_always tag
[...]

So with that we would have one if-statement, which indicates if we are fetching or not.

Should I dump my suggestion into this PR or wait until this PR is merged and then create a new one?

[ramaro]

@MatteoVoges thanks for getting this done!

Should I dump my suggestion into this PR or wait until this PR is merged and then create a new one?
I think doing this in a new PR makes sense to keep things simpler!

[ramaro]

This lgtm @MatteoVoges ! Would you mind updating the doc changes and title to force_fetch instead of fetch_always? We can merge straight after that,

[MatteoVoges]

Would you mind updating the doc changes and title to force_fetch instead of fetch_always?

Hey @ramaro,
I updated the title and the PR description. What else should be updated?

[ramaro]

@MatteoVoges there's some fetch_always usage in docs and code. Particularly because during our discussion, we've agreed to rename to force_fetch and this is not reflected for example in valid_target_obj(). Unless I'm missing something here 🤔

[MatteoVoges]

@ramaro , you're right. I updated it now. Please let me know if there is still something to do here.