apple-log

Safe Rust bindings for Apple's os_log on macOS — structured logging that integrates with Console.app and the log CLI.

Status: actively developed. v0.4 ships per-subsystem Logger, free-function logging via OS_LOG_DEFAULT, all 5 standard levels, public/private redaction control, default/disabled log handles, signpost helpers, and current activity-id introspection.

Pure C (with a tiny shim file built via cc) — zero Swift bridge.

Quick start

use apple_log::prelude::*;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    log(Level::Info, "starting up");
    log_with_privacy(Level::Debug, "token=secret", Privacy::Private);

    let logger = Logger::new("fish.doom.myapp", CATEGORY_POINTS_OF_INTEREST)?;
    logger.info("opening port 8080");
    logger.debug("tcp socket fd=7");

    let span = logger.signpost_id();
    logger.signpost_interval_begin(span, "startup");
    logger.signpost_interval_end(span, "startup");

    let activity = active_activity_ids();
    println!("current activity id: {}", activity.current);
    Ok(())
}

Then in another terminal:

log stream --predicate 'subsystem == "fish.doom.myapp"'
log show --info --debug --predicate 'subsystem == "fish.doom.myapp"' --last 1m

Or open Console.app and filter by subsystem.

Why os_log over log/tracing?

• System-integrated: visible in Console.app, log CLI, system-wide log archives — even after your binary exits.
• Persistent: error+ entries survive log rotation.
• Privacy-aware: Privacy::Public vs Privacy::Private controls redaction.
• No I/O cost: the kernel buffers log records; expensive-to-format messages are skipped when no subscriber is active.
• Free for the user: integrates with existing macOS log infrastructure (sysdiagnose, MDM exports, etc.).

You can still wire log/tracing on top — both crates support pluggable backends.

your-app ──► apple-log ──► /private/var/db/diagnostics
                                  │
                                  ├──► Console.app
                                  ├──► `log` CLI
                                  └──► sysdiagnose archives

Roadmap

• Logger::new(subsystem, category)
• Logger::{info, debug, error, fault} + log(level, msg) shortcut
• Public/private redaction control
• Logger::default() / Logger::disabled() handles
• Signpost ids, events, intervals, and animation intervals
• Signpost category constants (PointsOfInterest, DynamicTracing, DynamicStackTracing)
• Current activity id + parent-id introspection
• Activity creation / scope helpers for named activities
• log + tracing crate facade backends

License

Licensed under either of Apache-2.0 or MIT at your option.