change elasticsearch configuration DecodeHook function to handle string to []string

[leehinman]

What does this PR do?

Change elasticsearch configuration DecodeHook function to convert a single string to a slice of string with one value if the destination type is a slice of string.

Why is it important?

Beats configs allow for single values when the type is an slice. For example ssl.certificate_authorities is a slice of strings, but beat configuration allows for these to be a string instead of a slice with one entry.

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

How to test this PR locally

cd internal/pkg/otel/translate
go test .

Related issues

• Closes OTel manager failed: failed to generate otel config: error translating config for output: ... source data must be an array or slice, got string #11352

Questions to ask yourself

• How are we going to support this in production?
• How are we going to measure its adoption?
• How are we going to debug this?
• What are the metrics I should take care of?
• ...

[mergify]

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

[ycombinator]

While this change would work, it seems the only effect we're interested in is:

single values are converted to slices if required. Each element is weakly decoded. For example: "4" can become []int{4} if the target type is an int slice.

Since we're already defining a DecodeHook function, cfgDecodeHookFunc, would it be possible to use this function to convert T values into []T values if the target type is []T? That might be preferable/safer if we don't want or expect the rest of the implications of using WeaklyTypedInput?

[leehinman]

Since we're already defining a DecodeHook function, cfgDecodeHookFunc, would it be possible to use this function to convert T values into []T values if the target type is []T? That might be preferable/safer if we don't want or expect the rest of the implications of using WeaklyTypedInput?

I was waffling on this myself. I leaned towards the WeaklyTypedInput because beats config is so permissive, but since it set off your Spidey Senses too, l'll switch to the more targeted approach. If we hit more of these we can re-evaluate.

[elasticmachine]

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

[ycombinator]

LGTM once the linter failures are addressed.

[elasticmachine]

💛 Build succeeded, but was flaky

• Buildkite Build
• Commit: 92dcdfd

Failed CI Steps

• Unit tests - Windows 11

History

• 💔 Build #31959 failed 879b6bb
• 💛 Build #31893 was flaky 939d076
• 💔 Build #31824 failed d541e9e

cc @leehinman