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Alpine Linux uses {{pkg|openrc}} for its init system. Refer to the excellent guide [https://docs.alpinelinux.org/user-handbook/0.1a/Working/openrc.html working with OpenRC] from Alpine Linux documentation project to learn the basics. | |||
== Quick-Start Information == | == Quick-Start Information == | ||
The following commands are available to manage the init system: | The following commands are available to manage the init system: | ||
* {{Cmd|rc-update add service <runlevel>}} | * Basics: | ||
{{Cmd|# rc-update add <service> <runlevel>}} | |||
{{Cmd|# rc-update del <service> <runlevel>}} | |||
{{Cmd|# rc-service <service> <start stop restart> # ⇔ /etc/init.d/service <start stop restart>}} | |||
* To check services and their set runlevels: | |||
{{Cmd|rc-status}} | |||
* To change to a different runlevel: | |||
: | {{Cmd|# openrc <runlevel>}} | ||
{{ | * Reboot/Halt/Poweroff: (And their equivalent from traditional GNU/Linux systems) | ||
{{Cmd|# reboot # ⇔ shutdown now -r}} | |||
{{Cmd|# halt # ⇔ shutdown now -H}} | |||
{{Cmd|# poweroff # ⇔ shutdown now -P}} | |||
== Available Runlevels == | == Available Runlevels == | ||
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* '''default''' - Used if no runlevel is specified. (This is generally the runlevel you want to add services to.) | * '''default''' - Used if no runlevel is specified. (This is generally the runlevel you want to add services to.) | ||
* '''hotplugged''' | * '''hotplugged''' | ||
* '''manual''' | * '''manual''' | ||
The special runlevels are: | The special runlevels are: | ||
* '''sysinit''' - Brings up | * '''sysinit''' - Brings up system specific stuff such as <code>/dev</code>, <code>/proc</code> and optionally <code>/sys</code> for Linux based systems. It also mounts <code>/lib/rc/init.d</code> as a ramdisk using tmpfs where available unless <code>/</code> is mounted rw at boot. <code>'''rc'''</code> uses <code>/lib/rc/init.d</code> to hold state information about the services it runs. sysinit always runs when the host first starts and should not be run again. | ||
* '''boot''' - Generally the only services you should add to the boot runlevel are those which deal with the mounting of filesystems, set the initial state of attached peripherals and logging. Hotplugged services are added to the boot runlevel by the system. All services in the boot and sysinit runlevels are automatically included in all other runlevels except for those listed here. | * '''boot''' - Generally the only services you should add to the boot runlevel are those which deal with the mounting of filesystems, set the initial state of attached peripherals and logging. Hotplugged services are added to the boot runlevel by the system. All services in the boot and sysinit runlevels are automatically included in all other runlevels except for those listed here. | ||
* '''single''' - Stops all services except for those in the sysinit runlevel. | * '''single''' - Stops all services except for those in the sysinit runlevel. | ||
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* '''shutdown''' - Changes to the shutdown runlevel and then halts the host. | * '''shutdown''' - Changes to the shutdown runlevel and then halts the host. | ||
== | == Preventing slow services from delaying boot == | ||
Services that take a while to start will block the boot process until they complete. E.g.: <code>iwd</code> and <code>networking</code> might delay startup of an interactive system rather than start in the background. | |||
This can be remedied as per Patrycja's blog post titled [https://ptrcnull.me/posts/openrc-async-services/ OpenRC: Start services after login prompt]. This solution makes use of [https://wiki.gentoo.org/wiki/OpenRC/Stacked%20runlevel stacked runlevels]. | |||
<br> | |||
{{Warning| This solution requires editing the file '''/etc/inittab'''. If this file is edited wrongly, the system may not boot. Take adequate backup and gain necessary knowledge to edit files before proceeding.}} | |||
* Create a custom runlevel (name is “async” here, but it doesn’t matter) | |||
{{Cmd|# mkdir /etc/runlevels/async}} | |||
* Add default as a stacked runlevel | |||
{{Cmd|# rc-update add -s default async}} | |||
* Remove slow services from default and add them to async | |||
{{Cmd|# rc-update del chronyd}} | |||
{{Cmd|# rc-update add chronyd async }} | |||
* Add changing of runlevel to async by adding the line '''::once:/sbin/openrc async''' to /etc/inittab file: | |||
After rebooting, services from async will start separately. This change does not affect other services that start from Default runlevel and they may still block agetty from running due to the wait label. | |||
== cgroups v2 == | |||
Since {{pkg|openrc}} 0.51 cgroups v2, or "unified", is the default. | |||
You can enable hybrid cgroups v1 & v2 by editing <code>/etc/rc.conf</code> and setting <code>rc_cgroup_mode="hybrid"</code>. | |||
Then you should run | |||
{{Cmd|# rc-service cgroups start}} | |||
to take effect | |||
and | |||
{{Cmd|# rc-update add cgroups}} | |||
to auto mount the cgroup filesystem on boot | |||
[[Category:Booting]] | == See also == | ||
* [https://github.com/OpenRC/openrc/blob/master/user-guide.md OpenRC user Guide] | |||
* [https://github.com/OpenRC/openrc/blob/master/service-script-guide.md OpenRC Service Script Writing Guide] | |||
* [https://wiki.gentoo.org/wiki/OpenRC Gentoo Wiki] | |||
* [https://wiki.archlinux.org/title/OpenRC ArchWiki] | |||
* [https://wiki.postmarketos.org/wiki/OpenRC PostmarketOS Wiki] | |||
* [https://ptrcnull.me/posts/openrc-async-services/ Start services after login prompt] | |||
[[Category:Booting]] | |||
[[Category:System Administration]] | |||
[[Category:Services]] |
Latest revision as of 04:34, 25 September 2024
Alpine Linux uses openrc for its init system. Refer to the excellent guide working with OpenRC from Alpine Linux documentation project to learn the basics.
Quick-Start Information
The following commands are available to manage the init system:
- Basics:
# rc-update add <service> <runlevel>
# rc-update del <service> <runlevel>
# rc-service <service> <start stop restart> # ⇔ /etc/init.d/service <start stop restart>
- To check services and their set runlevels:
rc-status
- To change to a different runlevel:
# openrc <runlevel>
- Reboot/Halt/Poweroff: (And their equivalent from traditional GNU/Linux systems)
# reboot # ⇔ shutdown now -r
# halt # ⇔ shutdown now -H
# poweroff # ⇔ shutdown now -P
Available Runlevels
The available runlevels are:
- default - Used if no runlevel is specified. (This is generally the runlevel you want to add services to.)
- hotplugged
- manual
The special runlevels are:
- sysinit - Brings up system specific stuff such as
/dev
,/proc
and optionally/sys
for Linux based systems. It also mounts/lib/rc/init.d
as a ramdisk using tmpfs where available unless/
is mounted rw at boot.rc
uses/lib/rc/init.d
to hold state information about the services it runs. sysinit always runs when the host first starts and should not be run again. - boot - Generally the only services you should add to the boot runlevel are those which deal with the mounting of filesystems, set the initial state of attached peripherals and logging. Hotplugged services are added to the boot runlevel by the system. All services in the boot and sysinit runlevels are automatically included in all other runlevels except for those listed here.
- single - Stops all services except for those in the sysinit runlevel.
- reboot - Changes to the shutdown runlevel and then reboots the host.
- shutdown - Changes to the shutdown runlevel and then halts the host.
Preventing slow services from delaying boot
Services that take a while to start will block the boot process until they complete. E.g.: iwd
and networking
might delay startup of an interactive system rather than start in the background.
This can be remedied as per Patrycja's blog post titled OpenRC: Start services after login prompt. This solution makes use of stacked runlevels.
- Create a custom runlevel (name is “async” here, but it doesn’t matter)
# mkdir /etc/runlevels/async
- Add default as a stacked runlevel
# rc-update add -s default async
- Remove slow services from default and add them to async
# rc-update del chronyd
# rc-update add chronyd async
- Add changing of runlevel to async by adding the line ::once:/sbin/openrc async to /etc/inittab file:
After rebooting, services from async will start separately. This change does not affect other services that start from Default runlevel and they may still block agetty from running due to the wait label.
cgroups v2
Since openrc 0.51 cgroups v2, or "unified", is the default.
You can enable hybrid cgroups v1 & v2 by editing /etc/rc.conf
and setting rc_cgroup_mode="hybrid"
.
Then you should run
# rc-service cgroups start
to take effect
and
# rc-update add cgroups
to auto mount the cgroup filesystem on boot