mirror of
https://github.com/troglobit/finit.git
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Aaron Andersen
373738f3d1
in an initramfs, then transition to the real root filesystem. Useful for systems requiring early boot tasks like LUKS unlock, LVM activation, or network boot before mounting the real root. Adds INIT_CMD_SWITCH_ROOT API command, `initctl switch-root` subcommand, and HOOK_SWITCH_ROOT plugin hook point. The implementation gracefully stops services, moves virtual filesystems (/dev, /proc, /sys, /run) to the new root, deletes initramfs contents to free memory, then execs the new init as PID 1. See GitHub Discussion #292 for background.
83 lines
4.1 KiB
Markdown
83 lines
4.1 KiB
Markdown
Introduction
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============
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{ align=right width=40% }
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> Reverse engineered from the [EeePC fastinit][]
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> "gaps filled with frog DNA …"
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> — [Claudio Matsuoka][]
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Finit is a process starter and [supervisor][1] designed to run as PID 1
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on Linux systems. It consists of a set of [plugins](plugins.md) and can
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be set up using [configuration files](config/files.md). Plugins start
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at [hook points](plugins.md#hooks) and can run various set up tasks
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and/or install event handlers that later provide runtime services, e.g.,
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PID file monitoring, or [conditions](conditions.md).
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Features
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--------
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* [Runlevels](config/runlevels.md), defined per service
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* [One-shot tasks](config/task-and-run.md), [services](config/services.md) (daemons), or [SysV init][4] start/stop scripts
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* [Runparts](config/runparts.md) and `/etc/rc.local` support
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* Process supervision similar to [systemd][]
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* Fine-grained privilege control:
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- [Linux capabilities](config/capabilities.md) for minimal required privileges
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- [Supplementary groups](config/services.md#non-privileged-services) for multi-group resource access
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* [Sourcing environment files](config/service-env.md)
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* [Conditions](conditions.md) for network/process/custom dependencies
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* [Readiness notification](config/service-sync.md); PID files (native) for synchronizing system
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startup, support for systemd [sd_notify()][], or [s6 style][] too
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* Limited support for [tmpfiles.d(5)][] (no aging, attributes, or subvolumes)
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* [Pre/Post script actions](config/service-wrappers.md)
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* Rudimentary [templating support](config/templating.md)
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* [Tooling](initctl.md) to enable/disable services
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* [Automatic reload](features.md#automatic-reload) of modified configuration files (optional)
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* [Built-in getty](config/tty.md)
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* Built-in watchdog, with support for hand-over to [watchdogd][]
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* Built-in support for Debian/BusyBox [`/etc/network/interfaces`][3]
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* [Cgroups v2](config/cgroups.md), both configuration and monitoring in [`initctl top`](initctl.md)
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* [Plugin support](plugins.md) for customization
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* Proper [rescue mode](config/rescue.md) with bundled `sulogin` for protected maintenance shell
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* [Switch root](switchroot.md) support for initramfs-to-real-root transitions
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* Integration with [watchdogd][] for full system supervision
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* [Logging](config/logging.md) to kernel ring buffer before `syslogd` has started, see the
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recommended [sysklogd][] project for complete logging integration
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and how to log to the kernel ring buffer from scripts using `logger`
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For a more thorough overview, see the [Features](features.md) section.
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> [!TIP]
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> See [SysV Init Compatibility](config/sysv.md) for help to
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> quickly get going with an existing SysV or BusyBox init setup.
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Origin
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------
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This project is based on the [original finit][] by [Claudio Matsuoka][]
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which was reverse engineered from syscalls of the [EeePC fastinit][].
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Finit is developed and maintained by [Joachim Wiberg][] at [GitHub][6].
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Please file bug reports, clone it, or send pull requests for bug fixes
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and proposed extensions.
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[1]: https://en.wikipedia.org/wiki/Process_supervision
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[3]: https://manpages.debian.org/unstable/ifupdown2/interfaces.5.en.html
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[4]: https://en.wikipedia.org/wiki/Init
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[5]: https://en.wikipedia.org/wiki/Runlevel
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[6]: https://github.com/finit-project/finit
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[dinit]: https://davmac.org/projects/dinit/
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[systemd]: https://www.freedesktop.org/wiki/Software/systemd/
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[sd_notify()]: https://www.freedesktop.org/software/systemd/man/sd_notify.html
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[s6 style]: https://skarnet.org/software/s6/notifywhenup.html
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[tmpfiles.d(5)]: https://www.freedesktop.org/software/systemd/man/tmpfiles.d.html
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[EeePC fastinit]: https://web.archive.org/web/20071208212450/http://wiki.eeeuser.com/boot_process:the_boot_process
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[original finit]: http://helllabs.org/finit/
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[Claudio Matsuoka]: https://github.com/cmatsuoka
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[Joachim Wiberg]: https://troglobit.com
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[watchdogd]: https://troglobit.com/watchdogd.html
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[sysklogd]: https://github.com/troglobit/sysklogd/
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