systemd socket

A convenience crate for optionally supporting systemd socket activation.

About

The goal of this crate is to make socket activation with systemd in your project trivial. It provides a replacement for std::net::SocketAddr that allows parsing the bind address from string just like the one from std but on top of that also allows systemd://socket_name format that tells it to use systemd activation with given socket name. Then it provides a method to bind the address which will return the socket from systemd if available.

The provided type supports conversions from various types of strings and also serde and parse_arg via feature flag. Thanks to this the change to your code should be minimal - parsing will continue to work, it'll just allow a new format. You only need to change the code to use SocketAddr::bind() instead of TcpListener::bind() for binding.

You also don't need to worry about conditional compilation to ensure OS compatibility. This crate handles that for you by disabling systemd on non-linux systems.

Further, the crate also provides methods for binding tokio 0.2, 0.3, and async_std sockets if the appropriate features are activated.

Example

use systemd_socket::SocketAddr;
use std::convert::TryFrom;
use std::io::Write;

let mut args = std::env::args_os();
let program_name = args.next().expect("unknown program name");
let socket_addr = args.next().expect("missing socket address");
let socket_addr = SocketAddr::try_from(socket_addr).expect("failed to parse socket address");
let socket = socket_addr.bind().expect("failed to bind socket");

loop {
    let _ = socket
    .accept()
    .expect("failed to accept connection")
    .0
    .write_all(b"Hello world!")
    .map_err(|err| eprintln!("Failed to send {}", err));
}

Features

• enable_systemd - on by default, the existence of this feature can allow your users to turn off systemd support if they don't need it. Note that it's already disabled on non-linux systems, so you don't need to care about that.
• serde - implements serde::Deserialize for SocketAddr
• parse_arg - implements parse_arg::ParseArg for SocketAddr
• tokio - adds bind_tokio method to SocketAddr
• tokio_0_2 - adds bind_tokio_0_2 method to SocketAddr
• tokio_0_3 - adds bind_tokio_0_3 method to SocketAddr
• async_std - adds bind_async_std method to SocketAddr

MSRV

This crate must always compile with the latest Rust available in the latest Debian stable. That is currently Rust 1.48.1. (Debian 11 - Bullseye)

License

MITNFA