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