tracing-ndjson

A simple library for tracing in new-line delimited JSON format. This library is meant to be used with tracing as an alternative to the tracing_subscriber::fmt::json formatter.

The goal of this crate is to provide a flattend JSON event, comprising of fields from the span attributes and event fields, with customizeable field names and timestamp formats.

Features

• Configurable field names for target, message, level, and timestamp.
• Configurable timestamp formats
  • RFC3339 (2023-10-08T03:30:52Z),
  • RFC339Nanos (2023-10-08T03:30:52.123456789Z)
  • Unix timestamp (1672535452)
  • UnixMills (1672535452123)
• Captures all span attributes and event fields in the root of the JSON object. Collisions will result in overwriting the existing field.

Limitations

• When flattening span attributes and event fields, the library will overwrite any existing fields with the same name, including the built-in fields such as target, message, level, timestamp, file, and line.
• Non-determistic ordering of fields in the JSON object. (JSON objects are unordered)
• Currently only logs to stdout. (PRs welcome!)

Usage

Add this to your Cargo.toml:

[dependencies]
tracing = "0.1"
tracing-ndjson = "0.2"

use tracing_subscriber::prelude::*;

fn main() {
    let subscriber = tracing_subscriber::registry().with(tracing_ndjson::layer());

    tracing::subscriber::set_global_default(subscriber).unwrap();

    tracing::info!(life = 42, "Hello, world!");
    // {"level":"info","target":"default","life":42,"timestamp":"2023-10-20T21:17:49Z","message":"Hello, world!"}

    let span = tracing::info_span!("hello", "request.uri" = "https://example.com");
    span.in_scope(|| {
        tracing::info!("Hello, world!");
        // {"message":"Hello, world!","request.uri":"https://example.com","level":"info","target":"default","timestamp":"2023-10-20T21:17:49Z"}
    });
}

Examples

See the examples directory for more examples.

License

Licensed under MIT license