Logs

tracing::info!, debug!, warn!, error! are the framework’s logging API. Every event flows through the installed subscriber to the console and, when OTLP is configured, through the OpenTelemetryTracingBridge to OTel logs. Backend collectors index them alongside the traces of the same request.

Default level per layer

Concern	Target	Default level
HTTP request log	nest_rs::access	info
HTTP span	nest_rs::http	info
Route / endpoint mounting (boot)	nest_rs::routes	info
ORM queries	nest_rs::orm	trace
Layer composition (per-route guard/pipe/… chains)	nest_rs::layers	trace for the per-route effective-chain dump; debug for the redundant multi-scope lint (HTTP deduped once, WS per gateway); warn for actionable posture smells (reversed authn/authz order, denials, routes with no guard and no #[public] when no global pool is active)
Authn / Authz	nest_rs::authn / nest_rs::authz	info (denials warn)
WebSocket events	nest_rs::ws	info
Queue / Schedule	nest_rs::queue / nest_rs::schedule	info
Module lifecycle	nest_rs::module	info
App-specific spans	<app>::<feature>	info

Controllers, resolvers, gateways log at info on success. Services at debug. Repo at trace. Access denials and security events at warn+ so they appear under the default RUST_LOG=info. A production deploy should respect info — no per-request debug! on the hot path.

Structured fields

tracing::info!(
    target: "api::users",
    user_id = %id,
    actor = %auth.sub,
    "creating user",
);

Always prefer field = %value to format!("{}", value). The OTLP bridge serializes structured fields directly; a formatted string becomes opaque text the backend cannot filter on.

The request span (installed by the HTTP interceptor — see Traces) already carries request_id, actor_id, tenant_id when an authn module is mounted, so your structured fields layer on top of those.

Text vs JSON

The console layer ships both formats. Default is text (pretty for dev). For prod, set:

NESTRS_OPENTELEMETRY__LOG_FORMAT=json

JSON drops the current_span and span_list fields — the OTel export carries span structure, and duplicating it in the console line is noise.

Source location (file:line)

To trace a console line back to the exact source that emitted it, enable source location:

NESTRS_OPENTELEMETRY__LOG_SOURCE_LOCATION=true

Each event then carries the emitting file:line:

DEBUG nest_rs::layers: crates/nest-rs-core/src/layer_chain.rs: layer declared at multiple scopes…

Off by default — it widens every line and leaks source paths, so it stays out of production. Scaffolded projects turn it on in .env.development (next to LOG_LEVEL=debug), so a fresh nestrs new app ships with it on while developing and off everywhere else. Pin it explicitly with OpenTelemetryConfig::with_log_source_location(true).

Access log

The HTTP interceptor emits one access event per request on nest_rs::access, at end-of-body, with byte-accurate bytes and duration_ms:

INFO nest_rs::access: GET /users 200 28ms request_id=01J… bytes=412 client_ip=10.0.0.1 trace_id=4bf92f…

The same fields land on the OTel HTTP span (see Traces), so the access line and the span line up in the backend. Toggle the access line with NESTRS_HTTP__ACCESS_LOG=false; the OTel span still opens, so propagation and OTLP export keep working.

OTel logs bridge

The OpenTelemetryTracingBridge is wired in only when an OTLP endpoint is configured. Without an endpoint, the bridge is skipped — it pays a small per-event cost just to drop the event, which is not worth paying when console-only logging is the goal. When the endpoint is set, every tracing event becomes an OTel log record with the same target, level, fields and trace_id.