48 lines
2.5 KiB
Markdown
48 lines
2.5 KiB
Markdown
# systemd-ml
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`systemd-ml` provides `libsystemd`-like functionality for interacting with the systemd service
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manager, in self-contained ocaml code (with a bit of C). `systemd-ml` is integrated with `eio`,
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which provides for use in `eio`-based daemons
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Unfortunately, `systemd-ml` currently assumes usage of the `eio_linux` backend. It's hard to make
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code backend-agnostic because not enough functionality around Unix domain sockets is exposed by the
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high-level `eio` APIs, necessitating use of the low-level backend APIs. Therefore, it does not
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currently work on `eio_posix`, though future support is possible. Support for `eio_windows` is not
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planned, since there is no systemd port for windows.
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Additionally, some functionality that would be useful for systemd integration is currently not
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possible without library patches. This currently includes functionality for responding to memory
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pressure events.
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- `systemd-ml` with entry module `Systemd` is the main library
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- `systemd-ml.xlog` with entry module `Systemd_xlog` configures `xlog` to send log messages to
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journald
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- `systemd-ml.main` with entry module `Systemd_main` provdes a convenience function
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`Systemd_main.run` which handles common boilerplate operations for `Type=notify` or
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`Type=notify-reload` daemons with `xlog` output to journald
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Also note that per the license field in the package info, this package is not currently open source.
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If you have questions about this you should contact me
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## Features
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- detect
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[systemd](https://www.freedesktop.org/software/systemd/man/latest/systemd.exec.html#%24SYSTEMD_EXEC_PID)
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and
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[journald](https://www.freedesktop.org/software/systemd/man/latest/systemd.exec.html#%24JOURNAL_STREAM)
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presence
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- [rich journald output](https://systemd.io/JOURNAL_NATIVE_PROTOCOL/) using `xlog`
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- convenience functions to retrieve [directories passed by
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systemd](https://www.freedesktop.org/software/systemd/man/latest/systemd.exec.html#%24RUNTIME_DIRECTORY)
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- [service notifications](https://www.freedesktop.org/software/systemd/man/latest/sd_notify.html),
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with wrapper functions for common notification types
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- [fdstore](https://systemd.io/FILE_DESCRIPTOR_STORE/) functionality, and [socket
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activation](https://www.freedesktop.org/software/systemd/man/latest/systemd.socket.html)
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- [watchdog](https://www.freedesktop.org/software/systemd/man/latest/sd_watchdog_enabled.html)
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notifications
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features that would be nice to have but unfortunately require patches (eio does not currently
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support polling for POLLPRI)
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- [memory pressure](https://systemd.io/MEMORY_PRESSURE/)
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