sd-listen-fds

Exposes file descriptors passed in by systemd, the Linux init daemon, without dependencies, foreign or otherwise. Enables easy implementation of socket-activated services in pure Rust.

Unlike services that open sockets themselves, socket-activated services are started on-demand, may start up concurrently with their dependencies, and may be restarted without losing inbound data. Portable applications can call sd_listen_fds::get() and open their own socket if it succeeds with an empty Vec.

See also the sd_listen_fds API exposed by the foreign libsystemd library. Compared to using libsystemd bindings, this crate is smaller, safer, and builds everywhere.

Example

let fds = sd_listen_fds::get().unwrap();
let (_name, fd) = fds
    .into_iter()
    .next()
    .expect("must be launched as a systemd socket-activated service");
let socket = TcpListener::from(fd);

my-service.socket (see also systemd.socket)

[Socket]
# TCP port number. Other types of sockets are also possible.
ListenStream=1234

[Install]
WantedBy=sockets.target

[Unit]
Description=My Rust service
Documentation=https://example.com/my-service/

my-service.service (see also systemd.service)

[Service]
ExecStart=/path/to/my-service

[Unit]
Requires=my-service.socket
Description=My Rust service
Documentation=https://example.com/my-service/

License

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.