Go Observability

Observability is not optional for production services. Every service must produce structured logs, expose metrics, and propagate trace context. Use the stdlib log/slog for logging and OpenTelemetry for tracing and metrics.

Detailed reference material, loaded on demand:

• references/slog.md — handler setup, logger injection, child loggers.
• references/tracing.md — tracer provider, spans, propagation, shutdown.
• references/metrics.md — metric definitions, HTTP instrumentation.

Read a reference file only when the section below is not enough.

1. Structured Logging with slog

Use log/slog (Go 1.21+) with a JSON handler in production. Every line is key-value pairs, never a formatted sentence: