observability

[robfrank]

This pull request implements the planned improvements for Phase 3: Quality & Robustness, with a focus on backend observability and testing coverage. The most significant changes include adding Prometheus metrics and structured logging for backend observability, updating dependencies to support these features, and documenting implementation progress. Additionally, a new test verifies the metrics endpoint. The implementation plan and progress are clearly documented for ongoing and future work.

Backend Observability Enhancements:

• Added Prometheus metrics endpoint (/metrics) and integrated Micrometer for JVM/system metrics collection in WebBuilder.java. This includes registering metrics plugins and exposing /metrics for Prometheus scraping. [1] [2]
• Switched logging from SLF4J Simple to Logback for structured logging, and added a new logback.xml configuration for log formatting and log levels. [1] [2]

Testing Improvements:

• Implemented a new integration test (ObservabilityTest.java) to verify that the /metrics endpoint returns Prometheus-formatted metrics.

Documentation Updates:

• Added a comprehensive implementation plan for Phase 3 in .agent/workflows/phase3-implementation.md, detailing backend and frontend tasks, observability goals, and success criteria.
• Created a progress report (PHASE3_PROGRESS.md) outlining completed backend tests, current coverage, ongoing validation and observability work, and next steps.
• Updated ROADMAP.md to mark observability enhancements as completed.
• Updated developer documentation to include instructions for accessing Prometheus metrics.

[gemini-code-assist]

Summary of Changes

Hello @robfrank, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly advances the backend's quality and robustness by implementing key observability features and enhancing testing. It introduces Prometheus metrics for system monitoring and structured logging with Logback, alongside a new test to ensure metrics functionality. The changes also include comprehensive documentation updates detailing the Phase 3 implementation plan and progress.

Highlights

• Backend Observability: Integrated Prometheus metrics via Micrometer for JVM and system monitoring, and switched to Logback for structured logging to enhance backend observability.
• Testing Improvements: Introduced a new integration test (ObservabilityTest.java) to specifically validate the functionality and output of the new Prometheus /metrics endpoint.
• Documentation Updates: Updated project documentation, including a detailed Phase 3 implementation plan, a progress report, an updated roadmap marking observability as complete, and developer instructions for accessing metrics.

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[mergify]

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[gemini-code-assist]

Code Review

This pull request introduces significant observability improvements by adding a Prometheus metrics endpoint and switching to Logback for logging. The implementation is mostly solid, and the new test for the metrics endpoint is a good addition. I have a few suggestions for improvement: there's a potential memory leak in how some metrics are registered which should be addressed. Additionally, the logging configuration currently produces plain text logs, not structured logs as intended, and I've provided a suggestion to fix this. Finally, I've recommended a small change to make the new observability test more specific and robust.

[codacy-production]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
✅ +0.85% (target: -1.00%)	✅ 100.00%

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (af2bb20)	2452	1446	58.97%
Head commit (2835e70)	2469 (+17)	1477 (+31)	59.82% (+0.85%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#464)	17	17	100.00%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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