Add linting rules for replace directives in go.mod

[ycombinator]

What does this PR do?

This PR adds a golangci-lint linter rule for monitoring the use of replace directives in go.mod.

Why is it important?

Developers will sometimes use temporary replace directives in go.mod while developing a feature or fixing a bug that requires changes in dependencies as well. The linter rule introduced in this PR will ensure such temporary replace directives do not get checked in by accident, by complaining on the PR like so:

[mergify]

This pull request does not have a backport label. Could you fix it @ycombinator? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-v./d./d./d is the label to automatically backport to the 8./d branch. /d is the digit

NOTE: backport-skip has been added to this pull request.

[elasticmachine]

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• Start Time: 2023-05-09T20:36:16.925+0000

• Duration: 20 min 24 sec

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Test	Results
Failed	0
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Total	5674

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Name	Metrics % (covered/total)	Diff
Packages	98.592% (70/71)	👍
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Conditionals	100.0% (0/0)	💚

[blakerouse]

Nice!

[rdner]

I disagree with this change, the whole point of the linter is to catch things like this.

Why is it a problem to have the linter issue reported in a PR made for development?

The linter does not block the CI or merging, this is only a notification and a reviewer decides whether to approve a PR with a linter issue or not. We should not hide issues only because they don't look nice on PRs.

[ycombinator]

@rdner I'm not following what you're suggesting. The changes to the linter rules in this PR make things stricter. My intention was to have the linter complain on PRs for the following use case:

1. I make a PR in elastic-agent-libs for some functionality I need in elastic-agent.
2. Next, I make a PR in elastic-agent to use the functionality from elastic-agent-libs. To ensure that this PR works, I add a temporary replace directive in my elastic-agent's go.mod file, something like:

   replace github.com/elastic/elastic-agent-libs => github.com/ycombinator/elastic-agent-libs v0.0.0-20230511104653-a3c9ee8d16cb
   

With the linter changes in this PR, the replace directive will get flagged in CI. I think this is a good thing as it serves as reminder not to check in that change. It's not foolproof, yes, but it's better than nothing IMO. Can you explain why having such an automated check/reminder on the PR is a bad thing?

[rdner]

@ycombinator wait, this check was enabled before. That's why I thought you disabled it. Seems like @cmacknz removed it in #1478 not sure why, there is no explanation. Of course I'm for having this and not against, sorry, I misunderstood the change.

[ycombinator]

@rdner Thanks for pointing me to #1478. I will wait to get @cmacknz's opinion on this PR now, just to make sure it's not inadvertently re-introducing some problems that #1478 was trying to solve.

[cmacknz]

Given I left a comment for every removed linter in https://github.com/elastic/elastic-agent/pull/1478/files except this one, I am quite sure I simply removed gomoddirectives unintentionally.

[cmacknz]

It is also possible I didn't read the linter configuration closely enough to see that replace-allow-list: exists to silence the warnings for replace directives we want to keep. Either way, LGTM.