OpenRC

Alpine Linux uses openrc for its init system. The init system manages the services, startup and shutdown of your computer.

To learn the basics of OpenRC quickly, refer to the working with OpenRC guide from Alpine Linux documentation project.

Quickstart

Action	Command
Managing a service - start,stop and restart
Start <serviceName> now	`# rc-service <serviceName> start`
Stop <serviceName> now	`# rc-service <serviceName> stop`
Restart <serviceName> now	`# rc-service <serviceName> restart`
Adding and removing service from runlevels
Add <serviceName> to <runlevel>	`# rc-update add <serviceName> <runlevel>`
Remove <serviceName> from <runlevel>	`# rc-update del <serviceName> <runlevel>`
Check services in a runlevel and their status
To check status of <serviceName>	`$ rc-service <serviceName> status`
To view services configured at <runlevel>	`$ rc-update show <runlevel>`
To view currently active runlevels and state of services	`$ rc-status`
Check and manage runlevels
To view available runlevels	`$ rc-status -l`
To change to a different <runlevel>	`$ openrc <runlevel>`
Stacked runlevels
To add <s-runlevel> as a stacked <runlevel>	`# rc-update add -s <s-runlevel> <runlevel>`
User Services
To view currently active User runlevels and state of User services	`$ rc-status -U`
To change to a different user <runlevel>	`$ openrc -U <runlevel>`
Add User <serviceName> to user <runlevel>	`$ rc-update -U add <serviceName> <runlevel>`
View command usage
To view command usage for all openrc commands	`$ rc-status -h` or `$ rc-status --help`

Runlevels

A runlevel is basically a collection of services that needs to be started. Instead of random numbers they are named, and users can create their own if needed. The default startup uses the runlevels sysinit, boot, and default, in that order. Shutdown uses the shutdown runlevel.

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.

Stacked runlevels

Stacked runlevels allows "inheritance" of services. A few use cases are given below:

For more detailed information, refer Gentoo wiki.

Configuration

The main configuration file for OpenRC is /etc/rc.conf. The OpenRC service scripts for each service can be found at /etc/init.d/ and their respective service configuration files at /etc/conf.d/.

If the setting rc_parallel="YES" is configured, the OpenRC system tries to start services in parallel for a slight speed improvement. This setting however comes with a message from openRC developers:

Warning: whilst we have improved parallel, it can still potentially lock the boot process. Don't file bugs about this.

To improve boot times, consider the idea suggested in the preventing slow services from delaying boot section.

Cgroups

OpenRC supports cgroups v2 in the default configuration. To enable hybrid cgroups, edit the file /etc/rc.conf and change the setting for rc_cgroup_mode as follows:

Contents of /etc/rc.conf

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.

User services

OpenRC supports managing services for users. User services are currently experimental and available from v3.22 for the following:

Prerequisites

XDG_RUNTIME_DIR variable must be set

Config files

OpenRC uses ~/.config, if $XDG_CONFIG_HOME is unset. Adjust below instructions, if $XDG_CONFIG_HOME differs.

The main configuration file for OpenRC User services for a specific user is ~/.config/rc/rc.conf. The folder ~/.config/rc/runlevels/ contains the runlevels for OpenRC user services.

The service scripts for each OpenRC user service provided as part of official packages can be found at /etc/user/init.d/ and their respective service configuration files at /etc/user/conf.d/.

The folders ~/.config/rc/init.d/ and ~/.config/rc/conf.d/ have customized service scripts for User services files and their respective configuration files.

Configure environment variables

For Wayland

Allow propagation of the WAYLAND_DISPLAY environment variables by adding the following lines to file ~/.config/rc/rc.conf as follows:

Contents of ~/.config/rc/rc.conf

rc_env_allow="WAYLAND_DISPLAY"

For Xorg

If Elogind is not used, ensure that XDG_RUNTIME_DIR is set manually in ~/.xinitrc. For eg, for dwm add:

Contents of ~/.xinitrc

...
if [ -z "$XDG_RUNTIME_DIR" ]; then
	XDG_RUNTIME_DIR="/tmp/$(id -u)-runtime-dir"
	mkdir -pm 0700 "$XDG_RUNTIME_DIR"
	export XDG_RUNTIME_DIR
fi
openrc -U default
exec dwm

Note: For both the above cases, logout and login for the OpenRC user services to be started, before proceeding further.

User service management

Issue the command $ rc-status -Ur to view and verify the name of the current user runlevel before proceeding.

To start PipeWire user service, issue the command:

$ rc-service -U pipewire start

Verify that the above OpenRC user service is started before proceeding further:

$ rc-status -U

To enable PipeWire user service, issue the command:

$ rc-update -U add pipewire

The above steps can be repeated for other User services like pipewire-pulse, wlsunset etc

Note: Ensure that the startup of above services from /etc/xdg/autostart folder or from the startup/config file are stopped to prevent duplicate instance of services.

PAM support

The default installation of OpenRC user services is without PAM support. To ensure that user services do not linger on logout, enable PAM support for OpenRC user services by installing the openrc-user-pam package.

# apk add openrc-user-pam

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 using stacked runlevels as per Patrycja's blog post titled OpenRC: Start services after login prompt.

Warning: If the file /etc/inittab is edited wrongly, the system may not boot. Take backup and learn how to restore using rescue disk before proceeding.

Create a custom runlevel async:
# 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 default # rc-update add chronyd async
Add changing of runlevel to async by adding the line ::once:/sbin/openrc async to /etc/inittab file as follows:
Contents of /etc/inittab
... ::wait:/sbin/openrc default ::once:/sbin/openrc async -q # Set up a couple of getty's tty1::respawn:/sbin/getty 38400 tty1 ...

After rebooting, services from async will start separately. Other services started in default runlevel may still block agetty from running, due to the wait label.

Command usage

To view the command usage for all OpenRC commands (rc-update, rc-service, rc-status, openrc etc.) either use --help or (-h) flag. For eg:$ rc-update --help or $ rc-update -h will show usage information for rc-update.

The busybox command equivalent for traditional GNU/Linux systems is as follows:

# reboot # ⇔ shutdown now -r # halt # ⇔ shutdown now -H # poweroff # ⇔ shutdown now -P

Troubleshooting

Whenever a openRC service fails to run, to troubleshoot enable debugging option and run the command.

For example, if running the command rc-service greetd start causes greetd service to immediately crash, then alter the command to enable and view the debug:

# rc-service -d greetd restart

XDG_RUNTIME_DIR unset

While configuring user services, running the command $ doas rc-update add -U pipewire gui will generate the above error XDG_RUNTIME_DIR unset. Always issue the command as normal user $ rc-update add -U pipewire gui and do NOT use doas.

ERROR: user.greetd failed to start

While using user services with greetd, the above error message will appear. This failed error message for user.greetd service is harmless as per !81612#note_492385.

failed to create display

When using openRC user services for wlsunset, the following error message daemon.err wlsunset: failed to create display may appear. In this case, switch to a runlevel while inside your compositor's session. The steps are as follows:

Create a custom gui user runlevel:
$ mkdir -p ~/.config/rc/runlevels/gui
To start gui user runlevel, add the line openrc -U gui to the startup file of your compositor. For eg, for Sway add:
Contents of ~/.config/sway/config
... exec openrc -U gui
To enable wlsunset User service in gui user runlevel, issue the command:
$ rc-update -U add wlsunset gui
Repeat the process for other User services if required, so all user services are configured in this runlevel. Logout and login for the user services to be launched.