OpenRC

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

To learn the basics of OpenRC quickly, refer to the working with OpenRC guide from the 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`

Runlevels

A runlevel is basically a collection of services that needs to be started when certain conditions are met. Instead of using runlevel numbers, such as is used traditionally with SysV init, these are named, and users can create their own, if needed. The default startup uses the sysinit, boot, and default runlevels, 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 that one should add to the boot runlevel are those which deal with the mounting of filesystems, setting 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 for the "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/.

Command usage

To view the command usage for all OpenRC commands, use the --help or -h flag.

For eg:$ rc-update --help or $ rc-update -h will show usage information for rc-update.

OpenRC provides the following commands:

rc-update
rc-service
rc-status
openrc

Service management

To start, stop or restart a service ServiceName, for example, at the boot runlevel:

$ doas rc-service ServiceName start boot

$ doas rc-service ServiceName stop boot

Add or delete a service to/from the sequence of services that need to start automatically in future sessions at the default runlevel; note that the default runlevel is assumed, so it does not need to be stated explicitly:

$ doas rc-update add ServiceName default

$ doas rc-update del ServiceName

List the current status of all services; to display the status of all user services add -U :

$ rc-status

List the assigned runlevels of all services; to display the runlevels of user services add -U :

$ rc-update

Refer to the OpenRC user guide for more detailed information.

User services

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

Such services are said to be running in user mode and are managed with rc-update, rc-service, rc-status and openrc using the -U option (as distinct from the -u option), and without doas (nor as root).

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 is ~/.config/rc/rc.conf and ~/.config/rc/runlevels/ contains the User runlevels.

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/ can have user customized service scripts for User services and their respective configuration files. These scripts override official files at /etc/user/, if their service names match.

Configure environment variables

For Wayland

Tip: User services like wlsunset depend on the $WAYLAND_DISPLAY environment variable and associated variables. Hence, it is recommended to use gui runlevel for all User services in Wayland.

Allow propagation of the $WAYLAND_DISPLAY and associated 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"
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

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 current user runlevel as gui and default for Wayland and Xorg, respectively, before proceeding.

To start ServiceName user service, issue the command:

$ rc-service -U ServiceName start

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

$ rc-status -U

To enable ServiceName user service, issue the command:

$ rc-update -U add ServiceName

The above steps can be repeated for any user service, like pipewire, pipewire-pulse, wlsunset etc.

Note: Once a user service is configured, remove them from /etc/xdg/autostart folder or from the startup/config file to prevent duplicate instances.

PAM support

The default installation of OpenRC user services in Alpine Linux 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

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, one should run

# rc-service cgroups start

to take effect and

# rc-update add cgroups

to auto mount the cgroup filesystem on boot.

Preventing slow services from delaying system startup

Parallel services

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 startup times, consider the idea suggested in the preventing slow services from delaying startup section.

Stacked runlevel method

Services that take a while to start will block the boot process until they complete. E.g.: iwd,networking,chrony etc... 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 service from default runlevel and add them to the async runlevel:
# rc-update del <servicename> default # rc-update add <servicename> async
Enable the async runlevel 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.

Troubleshooting

Whenever a openRC service fails to run, troubleshoot by enabling a debugging option, and then run the command.

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

# 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 may appear:

daemon.err wlsunset: failed to create display

You will need the GUI runlevel for services that depend on $WAYLAND_DISPLAY. Refer Configure environment variables For Wayland section.