[confmap] Add error hint when invalid YAML was passed

[mx-psi]

Description

Add error hint field to surface YAML parsing errors. This only surfaces the error for top-level URIs but it's a step in the right direction.

Error when passing a file with contents [invalid:, as the config:

Before:

retrieved value (type=string) cannot be used as a Conf

After:

retrieved value (type=string) cannot be used as a Conf: assuming string type since contents are not valid YAML: yaml: line 1: did not find expected node content

Link to tracking issue

Updates #12000

Testing

Documentation

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.19%. Comparing base (7c1d694) to head (339c042).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #12180   +/-   ##
=======================================
  Coverage   92.19%   92.19%           
=======================================
  Files         465      465           
  Lines       25194    25204   +10     
=======================================
+ Hits        23228    23238   +10     
  Misses       1570     1570           
  Partials      396      396           

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[mattsains]

One thing I noticed a lot while researching this issue is that a lot of the test cases only test that some kind of error was produced, and not the content of the error. Perhaps you could consider fixing that as part of this PR. Examples:

• https://github.com/open-telemetry/opentelemetry-collector/blob/main/otelcol/collector_test.go#L315C1-L316C1
• https://github.com/open-telemetry/opentelemetry-collector/blob/main/confmap/provider_test.go#L64
• https://github.com/open-telemetry/opentelemetry-collector/blob/main/confmap/provider_test.go#L80

Improving these tests would prevent a regression like this in the future, they're easy to find by searching for require.Error and easy to fix by changing them to require.EqualError(t, err, "expected message"). You can even just run the tests with the expected message set to blank and figure out what the expected error is.

[mx-psi]

@mattsains That makes sense. I am not going to work on this further at least until next week, if you want to file a PR adding the EqualErrors or continue on top of this branch feel free to do so!

[mx-psi]

@mattsains Can you take another look?

[mattsains]

looks good to me! Although I'm not a maintainer on this repo

[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 14 days.

[mattsains]

Not stale, needs approver

[mx-psi]

cc @open-telemetry/collector-approvers PTAL!