Tracing

Reion can attach a trace id to every request so logs and spans can be correlated.

Trace id and logger

For each incoming request, Reion creates:

• ctx.trace.traceId: the request trace id
• ctx.logger: a request-scoped logger that includes the trace id in bindings

So you can safely use ctx.logger.info(...) inside routes and middleware.

Enabling / disabling

Tracing is controlled by:

• tracing: false in reion.config.ts
• REION_SKIP_TRACING=1 (or true) environment variable

Tracer hooks

If you configure these in reion.config.ts, Reion will call them around the request execution:

• traceStart: called when the request span starts
• tracer: called when the request span ends (with method, pathname, status, response size, etc.)

The default implementation logs a [datetime][traceId] method pathname line at start and end.