Joachim Wiberg
03a14bcaa5
Conditions in Finit are dependencies: if A is asserted, service B is
allowed to run. When A goes through FLUX (e.g., upstream reloads),
dependents are PAUSED and then simply resumed when the condition is
reasserted -- this is the correct behavior for barrier-style deps
like <pid/syslogd>.
However, some setups have tightly coupled services where dependents
must be reloaded/restarted when an upstream service reloads, not just
resumed. E.g., the FRR routing stack on Infix OS:
netd <pid/mgmtd> ← zebra <!pid/netd> ← {staticd,ripd} <!pid/zebra>
When netd reloads (SIGHUP), zebra and its dependents must be restarted
to pick up the new configuration.
The new '~' condition prefix marks a dependency as flux-sensitive:
service <!~pid/netd> name:zebra ...
When the upstream condition goes FLUX and returns to ON, the dependent
is reloaded (SIGHUP) or restarted (noreload '!') instead of merely
resumed. Transitivity follows naturally through the condition chain.
Closes #416
Closes #476
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
Introduction
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Reverse engineered from the EeePC fastinit
"gaps filled with frog DNA …"
— Claudio Matsuoka
Finit is a process starter and supervisor designed to run as PID 1 on Linux systems. It consists of a set of plugins and can be set up using configuration files. Plugins start at hook points and can run various set up tasks and/or install event handlers that later provide runtime services, e.g., PID file monitoring, or conditions.
Features
- Runlevels, defined per service
- One-shot tasks, services (daemons), or SysV init start/stop scripts
- Runparts and
/etc/rc.localsupport - Process supervision similar to systemd
- Fine-grained privilege control:
- Linux capabilities for minimal required privileges
- Supplementary groups for multi-group resource access
- Sourcing environment files
- Conditions for network/process/custom dependencies
- Readiness notification; PID files (native) for synchronizing system startup, support for systemd sd_notify(), or s6 style too
- Limited support for tmpfiles.d(5) (no aging, attributes, or subvolumes)
- Pre/Post script actions
- Rudimentary templating support
- Tooling to enable/disable services
- Automatic reload of modified configuration files (optional)
- Built-in getty
- Built-in watchdog, with support for hand-over to watchdogd
- Built-in support for Debian/BusyBox
/etc/network/interfaces - Cgroups v2, both configuration and monitoring in
initctl top - Plugin support for customization
- Proper rescue mode with bundled
suloginfor protected maintenance shell - Switch root support for initramfs-to-real-root transitions
- Integration with watchdogd for full system supervision
- Logging to kernel ring buffer before
syslogdhas started, see the recommended sysklogd project for complete logging integration and how to log to the kernel ring buffer from scripts usinglogger
For a more thorough overview, see the Features section.
Tip
See SysV Init Compatibility for help to quickly get going with an existing SysV or BusyBox init setup.
Origin
This project is based on the original finit by Claudio Matsuoka which was reverse engineered from syscalls of the EeePC fastinit.
Finit is developed and maintained by Joachim Wiberg at GitHub. Please file bug reports, clone it, or send pull requests for bug fixes and proposed extensions.