feat: add /metrics endpoint for observability by GodsBoy · Pull Request #6 · GodsBoy/repokeeper

GodsBoy · 2026-03-07T16:31:47Z

Summary

Adds a MetricsCollector class (src/metrics.ts) that tracks webhook event counts, processing duration, error counts, and AI call metrics
Exposes a GET /metrics endpoint on the Express server for monitoring
Includes 6 unit tests covering all collector functionality

Changes

src/metrics.ts — New MetricsCollector class with recordEvent(), recordError(), recordAICall(), getSnapshot(), and reset() methods
src/index.ts — Wire up /metrics route
tests/metrics.test.ts — Full test coverage

Test plan

pnpm build passes
pnpm test passes (91 tests)
Manually verify /metrics returns JSON with expected shape

Add MetricsCollector class that tracks: - Webhook event counts and processing duration - Error counts by type - AI call metrics (total, failures, avg duration) - Server uptime Exposes data via GET /metrics endpoint for monitoring. Includes 6 unit tests for the collector.

GodsBoy · 2026-03-07T16:31:55Z

PR Summary

Summary

This PR adds observability to the RepoKeeper application by introducing a MetricsCollector class that tracks webhook events, processing duration, errors, and AI call metrics. A new /metrics endpoint is exposed on the Express server to expose this data as JSON for monitoring purposes.

Files Changed

src/metrics.ts — New MetricsCollector class with methods to record events, errors, AI calls, and retrieve a snapshot of current metrics
src/index.ts — Added import and GET /metrics route that returns metrics.getSnapshot() as JSON
tests/metrics.test.ts — New test file with 6 unit tests covering all collector functionality

Flags

Breaking changes detected? No
Tests added or modified? Yes — 6 new tests added, all passing
Documentation updated? No

Files Changed (3)

src/index.ts (+5/-0) [modified]
src/metrics.ts (+102/-0) [added]
tests/metrics.test.ts (+60/-0) [added]

Size: medium (167 lines changed)
Generated by RepoKeeper

GodsBoy · 2026-03-07T16:33:37Z

PR Summary

Summary

This PR adds a new observability feature by introducing a MetricsCollector class that tracks webhook events, processing duration, errors, and AI call metrics. The collector is exposed via a new GET /metrics endpoint on the Express server, enabling real-time monitoring of application health and performance.

Files Changed

src/metrics.ts — New MetricsCollector class with methods to record events, errors, and AI calls, plus a singleton export
src/index.ts — Added import and /metrics route handler that returns metrics snapshot as JSON
tests/metrics.test.ts — Full test suite with 6 tests covering all collector functionality

Flags

Breaking changes? No
Tests added or modified? Yes (6 new tests added)
Documentation updated? No

Files Changed (3)

src/index.ts (+5/-0) [modified]
src/metrics.ts (+102/-0) [added]
tests/metrics.test.ts (+60/-0) [added]

Size: medium (167 lines changed)
Generated by RepoKeeper

GodsBoy

RepoKeeper Code Review

The pull request adds a metrics collection system with a new /metrics endpoint. The implementation is generally solid with good test coverage, but there are security and integration concerns that need addressing before merge.

Found 6 issue(s): 0 blocking, 2 warning(s), 4 suggestion(s)

Review by RepoKeeper

GodsBoy · 2026-03-07T16:33:45Z

src/index.ts

    res.json({ status: 'ok', version: '0.1.0' });
  });

+  app.get('/metrics', (_req, res) => {


⚠️ WARNING

The /metrics endpoint exposes internal application metrics without any authentication or authorization checks. This could leak sensitive operational information to unauthorized users. Consider adding authentication middleware or restricting this endpoint to localhost only.

GodsBoy · 2026-03-07T16:33:45Z

src/metrics.ts

+  recordEvent(eventType: string, durationMs: number): void {
+    const existing = this.events.get(eventType);
+    if (existing) {
+      existing.count++;


⚠️ WARNING

Calling new Date().toISOString() on every event recording (lines 38, 44) creates unnecessary object allocations. Consider using a single timestamp per batch or caching the current time to improve performance in high-throughput scenarios.

GodsBoy · 2026-03-07T16:33:45Z

src/metrics.ts

@@ -0,0 +1,102 @@
+import { log } from './logger.js';


💡 SUGGESTION

The MetricsCollector class is exported as a singleton instance but is never actually integrated with the rest of the application. The webhook handler, AI providers, and GitHub client don't call recordEvent(), recordError(), or recordAICall(). Add instrumentation throughout the codebase to make this metrics collection functional.

GodsBoy · 2026-03-07T16:33:45Z

src/metrics.ts

+  private startedAt: string;
+  private events: Map<string, MetricEntry> = new Map();
+  private errors: Map<string, number> = new Map();
+  private aiCallCount = 0;


💡 SUGGESTION

Memory leak potential: The events and errors Maps grow unbounded over the application's lifetime. For long-running applications, consider implementing a sliding window or TTL-based eviction strategy to prevent excessive memory consumption.

GodsBoy · 2026-03-07T16:33:45Z

tests/metrics.test.ts

@@ -0,0 +1,60 @@
+import { describe, it, expect, beforeEach } from 'vitest';


💡 SUGGESTION

The test file only tests the MetricsCollector class in isolation. Add integration tests in src/index.ts to verify that the /metrics endpoint is properly secured, returns valid JSON, and integrates correctly with the Express app.

GodsBoy · 2026-03-07T16:33:45Z

src/index.ts

    res.json({ status: 'ok', version: '0.1.0' });
  });

+  app.get('/metrics', (_req, res) => {


💡 SUGGESTION

The /metrics endpoint doesn't set appropriate HTTP headers (e.g., Content-Type is not explicitly set, no Cache-Control headers). Add explicit response headers for clarity and to prevent caching of dynamic metrics data.

GodsBoy added the size/medium label Mar 7, 2026

chore: clarify metrics singleton export

08d3fe1

GodsBoy commented Mar 7, 2026

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feat: add /metrics endpoint for observability#6

feat: add /metrics endpoint for observability#6
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		@@ -0,0 +1,60 @@
		import { describe, it, expect, beforeEach } from 'vitest';

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GodsBoy commented Mar 7, 2026

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