tracing-serde

An adapter for serializing tracing types using serde.

Overview

tracing-serde enables serializing tracing types using serde. tracing is a framework for instrumenting Rust programs to collect structured, event-based diagnostic information.

Traditional logging is based on human-readable text messages. tracing gives us machine-readable structured diagnostic information. This lets us interact with diagnostic data programmatically. With tracing-serde, you can implement a Subscriber to serialize your tracing types and make use of the existing ecosystem of serde serializers to talk with distributed tracing systems.

Serializing diagnostic information allows us to do more with our logged values. For instance, when working with logging data in JSON gives us pretty-print when we're debugging in development and you can emit JSON and tracing data to monitor your services in production.

The tracing crate provides the APIs necessary for instrumenting libraries and applications to emit trace data.

Usage

First, add this to your Cargo.toml:

[dependencies]
tracing = "0.1"
tracing-serde = "0.1"

Compiler support: requires rustc 1.39+

Next, add this to your crate:

#[macro_use]
extern crate tracing;
extern crate tracing_serde;

use tracing_serde::AsSerde;

Please read the tracing documentation for more information on how to create trace data.

This crate provides the as_serde function, via the AsSerde trait, which enables serializing the Attributes, Event, Id, Metadata, and Record tracing values.

For the full example, please see the examples folder.

Implement a Subscriber to format the serialization of tracing types how you'd like.

pub struct JsonSubscriber {
    next_id: AtomicUsize, // you need to assign span IDs, so you need a counter
}

impl Subscriber for JsonSubscriber {

    fn new_span(&self, attrs: &Attributes) -> Id {
        let id = self.next_id.fetch_add(1, Ordering::Relaxed);
        let id = Id::from_u64(id as u64);
        let json = json!({
        "new_span": {
            "attributes": attrs.as_serde(),
            "id": id.as_serde(),
        }});
        println!("{}", json);
        id
    }
    // ...
}

After you implement your Subscriber, you can use your tracing subscriber (JsonSubscriber in the above example) to record serialized trace data.

License

This project is licensed under the MIT license.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in Tokio by you, shall be licensed as MIT, without any additional terms or conditions.