Fix filesource provider with kubernetes symlink

[blakerouse]

What does this PR do?

Currently the filesource provider does not handle watching the correct paths because of how Kubernetes handles mounting sercrets into a container.

Adds a unit test to validate the filesource provider works with secret replacement from Kubernetes.

Why is it important?

Ensures that secret replacement changes are noticed by the filesource provider.

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

How to test this PR locally

mage unitTest

Related issues

• Closes filesource provider does re-read kubernetes mounted secrets #11051

[elasticmachine]

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

[mergify]

This pull request does not have a backport label. Could you fix it @blakerouse? 🙏
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]

💚 Build Succeeded

• Buildkite Build
• Commit: 4e085ad

History

• 💔 Build #30005 failed 6e74b89
• 💔 Build #29998 failed 4835f16

cc @blakerouse

[ycombinator]

Isn't this just target?

Suggested change

	finalTarget := filepath.Join(targetDir, targetBase)
	_, err = os.Readlink(finalTarget)
	_, err = os.Readlink(target)

[ycombinator]

Just a nitpick. Code LGTM — thanks for all the comments and the unit test.