Embedding rumqttd in your application

rumqttd can be embedded into your rust project, i.e. it can be used as a library. To do so, add rumqttd as a dependency in your Cargo.toml .

$ cargo add rumqttd

now we are good to go.

Setup configuration

The configuration struct is defined in rumqttd . We need Config for initiating Broker . Easiest way, which is also used in rumqttd/src/main.rs is to use config crate. rumqttd uses TOML file for configuration.

rumqttd::Config derives serde::Deserialize , therefore we can specify config in any file format which can be deserialized using serde.

here is minimal example of using config crate to create Config:

use rumqttd::Config;

// see docs of config crate to know more
let config = config::Config::builder()
    .add_source(config::File::with_name("rumqttd.toml"))
    .build()
    .unwrap();

// this is where we deserialize it into Config
let rumqttd_config: Config = config.try_deserialize().unwrap();

Spawning Broker

Once we have the config, we can pass it to rumqttd::Broker . To start the broker and servers as per specified in config, we use the start() method:

use rumqttd::Broker;
// ..
let mut broker = Broker::new(rumqttd_config);
// you can use better error handling instead on unwrap(). :)
broker.start().unwrap();
// broker.start() is a blocking method, therefore
// we don't get here untill every server spawned as per config crashes.
// If you want to do more things while broker is running, you should
// call start() in separate thread. e.g.
// ```
// thread::spawn(move || {
//   broker.start().unwrap();
// });
// ```

Collect logs

rumqttd uses tracing for collecting event-based diagnostic information, to get those logs, you would need to use a collector implementation compatible with tracing, such as tracing-subscriber :

use rumqttd::{Broker, Config, Notification};

use std::thread;

fn main() {
    let builder = tracing_subscriber::fmt()
        .pretty()
        .with_line_number(false)
        .with_file(false)
        .with_thread_ids(false)
        .with_thread_names(false);

    builder
        .try_init()
        .expect("initialized subscriber succesfully");

    // ....
    let mut broker = Broker::new(config);
    // ....
}

see other guides like Using Link to communicate with broker and Collecting Metrics to know what you can do with Broker.