dyson_log

Plug-and-play logging for Rust services built on tracing-subscriber with:

• Daily-rotating JSON log files
• Pretty console logs during development
• Optional Tokio Console integration for async task debugging
• Controlled entirely by environment variables

Install

Add this to your Cargo.toml:

[dependencies]
dyson_log = "0"
tracing = "0.1" # to use the `info!`, `warn!`, etc. macros

If you're in a workspace using this repo locally, you can depend on it by path while developing:

[dependencies]
dyson_log = { path = "../../crates/dyson_log" }
tracing = "0.1"

Usage

Call init_log() once at startup and keep the returned guard alive for the entire process lifetime to ensure logs are flushed.

use tracing::{info, warn};

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    // Initialize logging (honors environment variables below)
    let _guard = dyson_log::init_log();

    info!("service starting");
    // ... your app ...
    warn!("service stopping");
    Ok(())
}

Environment variables

• ENABLE_LOG: Enable/disable all logging
  • Default: 1
  • Example: ENABLE_LOG=0 to disable logging entirely
• LOG_PATH: Directory for log files
  • Default: logs
  • Example: LOG_PATH=/var/log/myapp
• LOG_FILE: Log filename (rotated daily in LOG_PATH)
  • Default: app.log
  • Example: LOG_FILE=server.log
• RUST_LOG: tracing filter
  • Examples: RUST_LOG=info, RUST_LOG=debug,my_crate=trace,hyper=warn
  • Uses tracing_subscriber::EnvFilter::from_default_env()
• TOKIO_CONSOLE_ENABLE: Enable Tokio Console subscriber
  • Default: disabled
  • Example: TOKIO_CONSOLE_ENABLE=1
  • Requires running the tokio-console app to view runtime metrics

What you get

• Console logs: human-readable with targets and line numbers.
• File logs: structured JSON lines, with spans and line numbers, one file per day (daily rotation).

Example JSON line (shape will vary):

{
  "timestamp":"2025-01-01T12:00:00Z",
  "level":"INFO",
  "target":"my_app::service",
  "message":"service starting",
  "span":{"name":"request","id":1},
  "line":42
}

Tips

• Set RUST_LOG for production to reduce noise while keeping diagnostics when needed.
• Keep the returned WorkerGuard (from init_log()) in a variable to ensure file logs are flushed on shutdown.
• Combine with tracing spans for rich, contextual logs across async boundaries.

License

Licensed under either of

• Apache License, Version 2.0
• MIT license

at your option.