# systemd-journal-logger-memfd-syscall (deprecated)

A pure Rust [log] logger for the [systemd journal][1] (fork supporting older glibc versions).

[log]: https://docs.rs/log
[1]: https://www.freedesktop.org/software/systemd/man/systemd-journald.service.html

## About this fork

**Update:** Since version 2.1.0,
[systemd-journal-logger is now using rustix](https://github.com/swsnr/systemd-journal-logger.rs/pull/24).
Rustix uses syscalls instead of calling the libc functions, so
systemd-journal-logger works again with old glibc versions and there is no need
to maintain this fork. This fork is now marked as deprecated.
`systemd-journal-logger >= 2.1` should be used instead.

This crate is a fork of
[systemd-journal-logger](https://github.com/swsnr/systemd-journal-logger.rs). The
only reason for the existence of this fork is that the maintainer of
`systemd-journal-logger`
[is not willing to support glibc versions older than 2.27](https://github.com/swsnr/systemd-journal-logger.rs/issues/22).

The
[only modification included in this fork](https://github.com/daniestevez/systemd-journal-logger.rs/commit/60700e9d911346f613137b63704811268f8807e1)
is calling the `memfd_create`
syscall (which is available starting with the Linux kernel 3.17) instead of the
`memfd_create()` libc function, which in glibc it is available starting with
glibc 2.27, while Rust supports glibc >= 2.17.

This fork will try to merge all the changes done upstream and release versions
in the same way as upstream.

## Usage

```console
$ cargo add systemd-journal-logger-memfd-syscall
```

Then initialize the logger at the start of `main`:

```rust
use log::{info, warn, error, LevelFilter};
use systemd_journal_logger_memfd_syscall::JournalLog;

JournalLog::new().unwrap().install().unwrap();
log::set_max_level(LevelFilter::Info);

info!("hello log");
warn!("warning");
error!("oops");
```

You can also add additional fields to every log message, such as the version of your executable:

```rust
use log::{info, warn, error, LevelFilter};
use systemd_journal_logger_memfd_syscall::JournalLog;

JournalLog::new()
    .unwrap()
    .with_extra_fields(vec![("VERSION", env!("CARGO_PKG_VERSION"))])
    .with_syslog_identifier("foo".to_string())
    .install().unwrap();
log::set_max_level(LevelFilter::Info);

info!("this message has an extra VERSION field in the journal");
```

These extra fields appear in the output of `journalctl --output=verbose` or in any of the JSON output formats of `journalctl`.

See [systemd_service.rs](./examples/systemd_service.rs) for a simple example of logging in a systemd service which automatically falls back to a different logger if not started through systemd.

## Related projects

- [rust-systemd](https://github.com/jmesmon/rust-systemd) provides a [logger implementation][1] based on the `libsystemd` C library.
- [slog-journald](https://github.com/slog-rs/journald) provides an [slog] logger for the systemd journal, also based on the `libsystemd` C library.
- [tracing-journald](https://github.com/tokio-rs/tracing/tree/master/tracing-journald) provides a tracing backend for the systemd journal, in a pure Rust implementation.

Both loggers use mostly the same fields and priorities as this implementation.

[1]: https://docs.rs/systemd/0.8.2/systemd/journal/struct.JournalLog.html
[slog]: https://github.com/slog-rs/slog

## License

Either [MIT](./LICENSE-MIT) or [Apache 2.0](./LICENSE-APACHE-2.0), at your option.