Add support for indexing log_attributes in OTLPConfig #15128

[samuelarogbonlo]

Summary

This PR adds support for indexing log_attributes in the OTLPConfig for Grafana Loki. Currently, Loki supports indexing resource_attributes but lacks similar functionality for log_attributes. This enhancement allows users to specify log_attributes to be indexed as labels directly from OTLP logs, improving flexibility and functionality.

This PR resolves Loki Issue #15128.

Changes Made

1. Extended OTLPConfig to process log_attributes with the action index_label.
2. Updated the logic in otlp_config.go to support log_attributes configuration:
   • Added support for indexing attributes.
   • Ensured compatibility with existing resource_attributes.
3. Added new test cases in otlp_config_test.go:
   • Validated that log_attributes with action: index_label are processed correctly.
   • Ensured proper handling of regex-based configurations.
   • Added checks for misconfigurations (e.g., both attributes and regex being set).
4. Ensured existing test cases for resource_attributes remain unaffected.

Testing Performed

Automated Tests

• Added the following test cases in otlp_config_test.go:

  • log_attributes indexing: Validates indexing of log_attributes with specified attributes.
  • log_attributes with regex: Ensures regex-based matching for log_attributes works.
  • unsupported action should error: Verifies that unsupported actions produce errors.
  • attributes and regex both not set should error: Tests error handling for invalid configurations.
  • attributes and regex both being set should error: Confirms that specifying both attributes and regex produces an error.

• Ran all tests in the pkg/loghttp/push package:

  go test ./pkg/loghttp/push/...

Test Results

All tests in pkg/loghttp/push passed successfully:

ok  	github.com/grafana/loki/v3/pkg/loghttp/push	0.790s

Checklist

• [✅] Code changes are committed and pushed to the feature branch.
• [✅] Added and updated test cases in otlp_config_test.go.
• [✅] All tests have passed locally.
• [✅] PR description includes:
  • [✅] Summary of the changes.
  • [✅] List of changes made.
  • [✅] Details of testing performed.
  • [✅] Example configuration.
  • [✅] Link to the related issue.

[CLAassistant]

All committers have signed the CLA.