runi-log

Structured logging with a Uni-style terminal format and a JSON fallback for non-terminal output. Built on top of tracing.

• Crate: runi-log on crates.io
• API reference: docs.rs/runi-log

Quick start

use runi_log::{info, warn, error};

fn main() {
    runi_log::init();

    info!(user = "alice", "request received");
    warn!(retries = 3, "slow upstream");
    error!("failed to connect");
}

The default format looks like:

2026-04-18 23:12:04.123-0700  INFO [my_app] request received - (main.rs:8)

The timestamp is local time with millisecond precision and timezone offset, the level is right-padded to 5 characters, and the target is reduced to its leaf segment (so my_app::api becomes api in the brackets).

Controlling log level

runi_log::init() reads the RUNI_LOG environment variable (default info), using the standard EnvFilter syntax:

RUNI_LOG=debug cargo run
RUNI_LOG=warn,my_crate=trace cargo run

Use init_with_env("MY_APP_LOG") to change the env var name, or init_with_level("debug") to hard-code a level.

Terminal vs JSON

init() detects whether stderr is a terminal:

• Terminal: colored Uni-style output with file/line locations.
• Redirected / piped: JSON with target, filename, and line_number fields, suitable for log aggregation pipelines.