Fix error logging for provider failures

[straistaru]

What does this PR do?

Avoid logging a nil error for provider exits.

Why is it important?

Some providers intentionally stop and return a nil error; they already log the exit reason internally. The previous log formatted a nil error into "%!s()", which can be confusing (e.g. provider "env" failed to run (will retry in 30s): %!s()). This change removes the incorrect formatting and only includes the error text when non-nil.

Checklist

• I have read and understood the pull request guidelines of this project.
• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [ ] I have made corresponding change to the default configuration files
• [ ] I have added tests that prove my fix is effective or that my feature works
• I have added an entry in ./changelog/fragments using the changelog tool
• [ ] I have added an integration test or an E2E test

Disruptive User Impact

None.

Related issues

• Closes Elastic Agent: env provider fails with unhelpful log message %!s(<nil>) #9284

[mergify]

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

• backport-./d./d is the label that automatically backports to the 8./d branch. /d is the digit
• backport-active-all is the label that automatically backports to all active branches.
• backport-active-8 is the label that automatically backports to all active minor branches for the 8 major.
• backport-active-9 is the label that automatically backports to all active minor branches for the 9 major.

[elasticmachine]

Pinging @elastic/elastic-agent-control-plane (Team:Elastic-Agent-Control-Plane)

[swiatekm]

If the provider already logged the reason internally, do we need to emit any more log lines? The line you're adding seems confusing as well. If we want to log something here, I'd drop the with a nil error, as that's an implementation detail.

[elasticmachine]

💛 Build succeeded, but was flaky

• Buildkite Build
• Commit: 1e88ef9

Failed CI Steps

History

• 💚 Build #27942 succeeded ac34d7e
• 💔 Build #27890 failed ac34d7e
• 💚 Build #27813 succeeded ce0296e

cc @straistaru

[github-actions]

@Mergifyio backport 8.18 8.19 9.0 9.1 9.2

[mergify]

backport 8.18 8.19 9.0 9.1 9.2

✅ Backports have been created

• #10380 [8.18] (backport #10217) Fix error logging for provider failures has been created for branch 8.18
• #10381 [8.19] (backport #10217) Fix error logging for provider failures has been created for branch 8.19
• #10382 [9.0] (backport #10217) Fix error logging for provider failures has been created for branch 9.0
• #10383 [9.1] (backport #10217) Fix error logging for provider failures has been created for branch 9.1
• #10384 [9.2] (backport #10217) Fix error logging for provider failures has been created for branch 9.2