feat(metrics): implement Prometheus metrics collection & /metrics endpoint#342
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OthmanImam merged 1 commit intoJun 23, 2026
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…ndpoint - Add MetricsModule with global HTTP interceptor for request tracking - Expose /metrics endpoint (GET, public, Prometheus text format) - Define 20+ custom metrics: HTTP, auth, DB, job queue, business - Add auth-specific counters: attempts, success, failures - Wire MetricsModule into AppModule - Add Grafana dashboard template (docs/dashboards/stellaiverse-backend.json) - Add metrics documentation (docs/METRICS.md) - 10 unit/integration tests for interceptor and controller Closes StellAIverse#311
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Summary
Implements full Prometheus metrics integration for the StellAIverse backend, satisfying all acceptance criteria from issue #311.
Implementation Details
MetricsModule (
src/metrics/)MetricsController— exposesGET /metrics(public, no auth required) returning Prometheus text formatMetricsInterceptor— global NestJS interceptor that automatically tracks every HTTP request (latency, total count, in-progress, errors)MetricsModule— registers the controller and wires the interceptor asAPP_INTERCEPTORinAppModuleCustom Metrics (
src/config/metrics.ts)20+ custom metrics implemented with the
stellaiverse_prefix:http_request_duration_seconds(histogram),http_requests_total(counter),http_requests_in_progress(gauge),http_errors_total(counter)auth_attempts_total,auth_success_total,auth_failures_total,user_signups_total,active_usersdatabase_query_duration_seconds(histogram),active_connections(gauge)job_duration_seconds,job_success_total,job_failure_total,queue_lengtherrors_totalNode.js default metrics (CPU, memory, event loop, GC, file descriptors, etc.) are also collected via
collectDefaultMetrics.Grafana Dashboard
Pre-built dashboard template at
docs/dashboards/stellaiverse-backend.json— importable directly into Grafana. Panels cover HTTP traffic, latency percentiles (p50/p95), error rate, auth rate, DB query latency, Node.js heap, and event loop lag.Documentation
docs/METRICS.md— complete reference for all metrics, adding new metrics, Prometheus scrape config, and Grafana import instructions.Validation Results
Build: ✅
npm run build— webpack compiled successfullyNew tests (10 passing):
src/metrics/metrics.interceptor.spec.ts— 4 tests (success path, error path, default 500, no-request passthrough)src/metrics/metrics.controller.spec.ts— 6 tests (endpoint format, default metrics, HTTP metrics, auth metrics, DB metrics, schema prefix validation)Pre-existing failures (unrelated, confirmed on main before this branch):
10 test suites fail with
Cannot find module 'src/...'— a module path resolution issue in Jest config that predates this PR.Closes
Closes #311