G. Pape
runit

runit - replacing init

How to replace sysvinit on GNU/Linux
How to replace init on *BSD
How to replace init on MacOSX
How to replace init on Solaris

Replacing sysvinit (GNU/Linux)

 Follow these steps to migrate from sysvinit to runit on Debian GNU/Linux (woody). The /sbin/init binary is not replaced until step 6, runit is the default Unix process no 1 after step 7.

If you have installed the precompiled Debian package, start at step 3.

Step 1: The three stages

runit looks for the three stages implementing the system's booting, running and shutdown in /etc/runit/1, /etc/runit/2 and /etc/runit/3, create the files now: 
 # mkdir -p /etc/runit
 # cp -p /package/admin/runit/etc/debian/[123] /etc/runit/
Create also a getty service directory: 
 # mkdir -p /etc/sv/getty-5
 # cp -p /package/admin/runit/etc/debian/getty-tty5/run /etc/sv/getty-5/
 # cp -p /package/admin/runit/etc/debian/getty-tty5/finish /etc/sv/getty-5/
If you want runit to handle the ctrl-alt-del keyboard request, do: 
 # cp -p /package/admin/runit/etc/debian/ctrlaltdel /etc/runit/

Step 2: The runit programs

The runit programs must reside on the root partition, copy them to /sbin: 
 # cp -p /package/admin/runit/command/runit* /sbin/

Step 3: The getties

At least one getty must run in stage 2 so that you are able to login. Choose a free tty, say tty5, where sysvinit is not running any getty (edit /etc/inittab and kill -HUP 1 if needed), and tell runsvdir about the getty-5 service: 
 # mkdir -p /var/service
 # ln -s /etc/sv/getty-5 /var/service/
Start runit's stage 2 for testing: 
 # /etc/runit/2 &
And check that the getty is running.

Step 4: Reboot into runit for testing

Boot your system with runit for the first time. This does not change the default boot behavior of your system, lilo will be told to use runit just once: If you are not using lilo as boot loader, refer to the documentation of your boot loader on how to pass init=/sbin/runit-init to the kernel.

Step 5: Service migration

The goal is to migrate all services from sysvinit scheme to the runit service supervision design; take a look at these run scripts for popular services. The migration can be done smoothly. For those services that are not migrated to use run scripts yet, add the corresponding init-script startup to /etc/runit/1, e.g.: 
 #!/bin/sh
 # one time tasks

 /etc/init.d/kerneld start
 /etc/init.d/rmnologin

 touch /etc/runit/stopit
 chmod 0 /etc/runit/stopit
It is possible to just add /etc/init.d/rc 2 for having all services from the former runlevel 2 started as one time tasks, but keep the goal above in mind, supervising services has great advantages.

Repeat step 4 and 5, using /sbin/runit-init 6 to reboot the system, until you are satisfied with your services startup. If anything goes wrong, reboot the system into the default sysvinit /sbin/init and repair the runit stages, then start again at step 4.

Step 6: Replace /sbin/init

Now it is time to replace the sysvinit /sbin/init binary: 
 # mv /sbin/init /sbin/init.sysv
 # ln -s runit-init /sbin/init

Step 7: Final reboot

The last step is to do the final reboot to boot the system with the new default Unix process no 1 runit. 
 # init 6
To report success: 
 # ( uname -a ; cat /etc/runit/[123] ) |mail pape-runit-1.6.0@smarden.org

Replacing init (*BSD)

 Follow these steps to migrate from init to runit on OpenBSD 2.9 or FreeBSD 4.4. The /sbin/init binary is not replaced until step 4.

Step 1: The three stages

runit looks for the three stages implementing the system's booting, running and shutdown in /etc/runit/1, /etc/runit/2 and /etc/runit/3 respectively. Create the scripts now: 
 # mkdir -p /etc/runit

OpenBSD 2.9:
 # cp -p /package/admin/runit/etc/openbsd/[123] /etc/runit/

FreeBSD 4.4:
 # cp -p /package/admin/runit/etc/freebsd/[123] /etc/runit/
Remove the svscanboot startup from /etc/rc.local by deleting the line csh -cf '/command/svscanboot &' (this normally is the last one); runit will start runsvdir in stage 2 after running rc.local in stage 1. 
 # vi /etc/rc.local

Step 2: The runit programs

The runit programs must reside on the root partition, install them into /sbin: 
 # install -m0500 /package/admin/runit/command/runit* /sbin/

Step 3: The getties

At least one getty must run in stage 2 so that you are able to login. To have it run on the virtual console no 5, create the getty-5 service directory: 
 # mkdir -p /etc/sv/getty-5

OpenBSD 2.9:
 # cp -p /package/admin/runit/etc/openbsd/getty-ttyC4/run /etc/sv/getty-5/
 # cp -p /package/admin/runit/etc/openbsd/getty-ttyC4/finish /etc/sv/getty-5/

FreeBSD 4.4:
 # cp -p /package/admin/runit/etc/freebsd/getty-ttyv4/run /etc/sv/getty-5/
 # cp -p /package/admin/runit/etc/freebsd/getty-ttyv4/finish /etc/sv/getty-5/
and tell runsvdir about the getty-5 service: 
 # mkdir -p /var/service
 # ln -s /etc/sv/getty-5 /var/service/
Start runit's stage 2 for testing: 
 # /etc/runit/2 &
And check that the getty is running.

Step 4: Replace the /sbin/init binary

Before replacing the init binary, make sure that you are able to boot your system alternatively, e.g. with a boot floppy, to restore the former /sbin/init if anything goes wrong.

Make a backup copy of the current /sbin/init program and replace it with /sbin/runit-init: 

 # cp -p /sbin/init /sbin/init.bsd
 # install /sbin/runit-init /sbin/init
Boot your system with runit for the first time: 
 # reboot
Watch the console output while runit boots up the system. Switch to the virtual console 5 (CTRL-ALT-F5) when stage 2 is reached, a getty should run there, you are able to login.

Use init 6 to reboot and init 0 to halt a system that runs runit. This will cause runit to enter stage 3 which runs /sbin/reboot or /sbin/halt as last command.

To report success: 

 # ( uname -a ; cat /etc/runit/[123] ) |mail pape-runit-1.6.0@smarden.org

Step 5: Service migration

The goal is to migrate all services from /etc/rc.* scheme to the runit service supervision design; take a look at these run scripts for popular services. The migration can be done smoothly. By default runit runs the /etc/rc scripts in stage 1 as a one time task, so the services are started automatically: 
 #!/bin/sh
 # system one time tasks

 /bin/sh /etc/rc autoboot

 touch /etc/runit/stopit
 chmod 0 /etc/runit/stopit
To migrate a service, create a service directory, disable the service if it is running, disable the service in /etc/rc.conf or remove the service startup from the /etc/rc.* scripts and tell runsvdir about the new service.

Replacing init on MacOSX

 Replacing init on MacOSX is not yet supported. Please refer to the instructions on how to use runit service supervision with the MacOSX init scheme.

Replacing init on Solaris

 Replacing init on Solaris is not yet supported. Please refer to the instructions on how to use runit service supervision with the Solaris sysvinit scheme.
Gerrit Pape <pape@smarden.org>
$Id: replaceinit.html,v 1.72 2006/06/20 20:34:46 pape Exp $