Observability (OpenTelemetry, Prometheus, health checks)

[andreahlert]

Problem

The current logging system is basic (structured stderr output). Production deployments need metrics, traces, and detailed health checks.

Proposal

Prometheus metrics endpoint

GET /metrics

Exports:

• kilnx_http_requests_total{method, path, status}
• kilnx_http_request_duration_seconds{method, path}
• kilnx_db_queries_total{type} (select, insert, update, delete)
• kilnx_db_query_duration_seconds
• kilnx_sessions_active
• kilnx_jobs_total{status} (pending, completed, failed)

Enhanced health check

GET /healthz
{
  "status": "ok",
  "uptime": "2h34m",
  "database": "ok",
  "sessions": 42,
  "version": "1.5.0"
}

OpenTelemetry traces (optional)

config
  telemetry: env OTEL_ENDPOINT

• HTTP request spans
• SQL query spans
• Email/job spans

Config

log
  level: info
  queries: slow > 100ms
  requests: all
  metrics: /metrics
  telemetry: env OTEL_EXPORTER_OTLP_ENDPOINT

Why

Production visibility. Developers need to know what their app is doing without adding external APM tools.

[github-actions]

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