Logging

Every container provides Logger. An Arc<Logger> field in an #[injectable] class is resolved specially with the class name as its scope:

#![allow(unused)]
fn main() {
#[caelix::injectable]
struct OrdersService {
    logger: Arc<Logger>,
}

self.logger.info("order accepted");
self.logger.warn("inventory is low");
self.logger.error("payment failed");
self.logger.debug("retry state updated");
}

Logger::new("scope"), Logger::for_type::<T>(), and context() are available for manual construction. CAELIX_LOG selects error, warn, info/log, or debug. If absent or invalid, Caelix reads an applicable caelix, caelix_core, or caelix-core directive from RUST_LOG, then defaults to debug. Framework startup, module/provider initialization, route mapping, readiness, shutdown, and internal server failures use the same logger.

Generated controller routes include correlation metadata on every logged server error:

[2026-07-26T14:32:08.190Z ERROR caelix::error] 500 Internal Server Error: Internal Server Error | source: database unavailable | method=GET path="/orders" request_id="9e285a20-9405-4cc8-8941-0f758d84f524" trace_id="4bf92f3577b34da6a3ce929d0e0e4736" service="orders-api" environment="production"

Caelix accepts X-Request-Id and X-Trace-Id, and understands the trace ID inside a W3C traceparent header. Missing request IDs are generated as UUIDs; invalid correlation headers are ignored. X-Request-Id and X-Trace-Id are included on the response so clients can report them.

Set CAELIX_SERVICE_NAME and CAELIX_ENVIRONMENT to identify the deployment. OTEL_SERVICE_NAME is also accepted for the service name; APP_ENV and ENVIRONMENT are environment fallbacks. Defaults are application and development.

Default startup output is intentionally compact:

[2026-07-26T14:32:08.184Z INFO  caelix::bootstrap] Building application
[2026-07-26T14:32:08.186Z INFO  caelix::routes] 3 routes registered across 1 controller
[2026-07-26T14:32:08.187Z INFO  caelix::server] Listening on http://127.0.0.1:3000 in 12ms

The ready event is written only after the server successfully binds. Individual module, provider, controller, and route events are included by default. Set CAELIX_LOG=info for compact startup output. In-process TestApplication compilation does not emit server startup events.

Actix access logs

#![allow(unused)]
fn main() {
Application::new::<AppModule>()
    .await?
    .logging(Logging::default())
    .listen("127.0.0.1:3000")
    .await?;
}

Logging::default() enables compact method, path, status, and duration logs. Logging::info() enables the detailed Actix-compatible format: peer address, request line/protocol, status, response size, referrer, user agent, and duration. Use .access_log(false) to disable middleware completely.

Explicit .logging(...) wins. If it is omitted, CAELIX_HTTP_LOG is checked, then the legacy CAELIX_ACCESS_LOG; recognized boolean values decide whether compact access logging is enabled. The default fallback is disabled.

Request workers enqueue access entries to a dedicated buffered writer. The queue capacity is 65,536; when full, new entries are dropped instead of blocking requests. Monitor dropped_http_request_logs(). Caelix reports drops to stderr at most once per second. Buffered responses report their byte count; a streaming response whose final size is unknown logs -.

Axum

Axum has the scoped application/framework Logger, but does not expose Actix’s Logging application configuration or install this access-log middleware. Attach a Tower HTTP tracing/access-log layer with Application::layer when Axum request logs are required.