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<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
<html>
<head>
<title>runit - replacing init</title>
</head>
<body>
<a href="http://smarden.org/pape/">G. Pape</a><br>
<a href="index.html">runit</a>
<hr>
<h1>runit - replacing init</h1>
<hr>
<a href="#sysvinit">How to replace sysvinit on GNU/Linux</a><br>
<a href="#bsdinit">How to replace init on *BSD</a>
<hr>
<a name="sysvinit"><h2>Replacing sysvinit (GNU/Linux)</h2></a>
Follow these steps to migrate from <i>sysvinit</i> to <i>runit</i> on
<a href="http://www.debian.org/releases/woody/">Debian GNU/Linux (woody)</a>.
The <tt>/sbin/init</tt> binary is not replaced until step 6, <i>runit</i> is
the default Unix process no 1 after step 7.
<p>
If you have installed the precompiled Debian package, start at step 3.
<h3>Step 1: The three stages</h3>
<i>runit</i> looks for the three stages implementing the system's
<i>booting</i>, <i>running</i> and <i>shutdown</i> in <tt>/etc/runit/1</tt>,
<tt>/etc/runit/2</tt> and <tt>/etc/runit/3</tt>, create the files now:
<pre>
# mkdir -p /etc/runit
# cp -p /package/admin/runit/etc/debian/[123] /etc/runit/
</pre>
Create also a getty service directory:
<pre>
# mkdir -p /etc/runit/getty-5
# cp -p /package/admin/runit/etc/debian/getty-tty5/run /etc/runit/getty-5/
</pre>
If you want <i>runit</i> to handle the ctrl-alt-del keyboard request, do:
<pre>
# cp -p /package/admin/runit/etc/debian/ctrlaltdel /etc/runit/
</pre>
<h3>Step 2: The runit programs</h3>
The <i>runit</i> programs must reside on the root partition, copy them to
<tt>/sbin</tt>:
<pre>
# cp -p /package/admin/runit/command/runit* /sbin/
</pre>
<h3>Step 3: The getties</h3>
At least one getty must run in stage 2 so you are able to login, choose a
free <tt>tty</tt>, say <tt>tty5</tt>, where <i>sysvinit</i> is not running
any getty (edit <tt>/etc/inittab</tt> and <tt>kill -HUP 1</tt> if
needed) and tell <a href="http://cr.yp.to/daemontools/svscan.html">svscan</a>
about the getty-5 <i>service</i>:
<pre>
# ln -s /etc/runit/getty-5 /service/
</pre>
Check if the getty is running.
<h3>Step 4: Reboot into runit for testing</h3>
Boot your system with <i>runit</i> for the first time. This does not change
the default boot behavior of your system, <i>lilo</i> will be told to use
<i>runit</i> just once:
<ul>
<li>reboot the system
<li>enter the following on the lilo prompt:<br>
<tt>init=/sbin/runit-init</tt>
<li>watch the console output while <i>runit</i> boots up the system
<li>switch to <tt>tty5</tt> when stage 2 is reached, a <tt>getty</tt>
should run there, you are able to login.
</ul>
If you are not using <i>lilo</i> as boot loader, refer to the documentation
of your boot loader on how to pass <tt>init=/sbin/runit-init</tt> to the
kernel.
<h3>Step 5: Service migration</h3>
The goal is to migrate all services from <i>sysvinit</i> scheme to the
<a href="http://cr.yp.to/daemontools.html">daemontools</a> design; take a
look at these <a href="runscripts.html">run scripts</a> for popular
services. The migration can be done smoothly. For those services that are
not migrated to use <tt>run</tt> scripts yet, add the corresponding
<tt>init</tt>-script startup to <tt>/etc/runit/1</tt>, e.g.:
<pre>
#!/bin/sh
# one time tasks
rm -f /etc/runit/stopit
/etc/init.d/rcS
/etc/init.d/kerneld start
/etc/init.d/rmnologin
exit 0
</pre>
It is possible to just add <tt>/etc/init.d/rc 2</tt> 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.
<p>
Repeat step 4 and 5, using <tt><b>/sbin/runit-init 6</b></tt> to reboot the
system, until you are satisfied with your services startup. If anything goes
wrong, reboot the system into the default <i>sysvinit</i> <tt>/sbin/init</tt>
and repair the <i>runit</i> stages, then start again at step 4.
<h3>Step 6: Replace /sbin/init</h3>
Now it is time to replace the <i>sysvinit</i> <tt>/sbin/init</tt> binary:
<pre>
# mv /sbin/init /sbin/init.sysv
# ln -s runit-init /sbin/init
</pre>
<h3>Step 7: Final reboot</h3>
The last step is to do the final reboot to boot the system with the new
default Unix process no 1 <i>runit</i>.
<pre>
# shutdown -r now
</pre>
To report success:
<pre>
# ( uname -a ; cat /etc/runit/[123] ) | mail pape-runit-0.9.1@smarden.org
</pre>
<hr>
<a name="bsdinit"><h2>Replacing init (*BSD)</h2></a>
Follow these steps to migrate from <i>init</i> to <i>runit</i> on
<a href="http://www.openbsd.org/">OpenBSD 2.9</a> or
<a href="http://www.freebsd.org/">FreeBSD 4.4</a>. The
<tt>/sbin/init</tt> binary is not replaced until step 4.
<h3>Step 1: The three stages</h3>
<i>runit</i> looks for the three stages implementing the system's
<i>booting</i>, <i>running</i> and <i>shutdown</i> in <tt>/etc/runit/1</tt>,
<tt>/etc/runit/2</tt> and <tt>/etc/runit/3</tt>, create the files now:
<pre>
# 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/
</pre>
Remove the <tt>svscanboot</tt> startup from <tt>/etc/rc.local</tt> by
deleting the line <tt>csh -cf '/command/svscanboot &'</tt> (this normally
is the last one); <i>runit</i> will start
<a href="runsvdir.8.html">runsvdir</a> in stage 2 after running
<tt>rc.local</tt> in stage 1.
<pre>
# vi /etc/rc.local
</pre>
<h3>Step 2: The runit programs</h3>
The <i>runit</i> programs must reside on the root partition, install them
into <tt>/sbin</tt>:
<pre>
# install -m0500 /package/admin/runit/command/runit* /sbin/
</pre>
<h3>Step 3: The getties</h3>
At least one getty must run in stage 2 so you are able to login. To have it
run on the virtual console no 5, create the getty-5 service directory:
<pre>
# mkdir -p /etc/runit/getty-5
OpenBSD 2.9:
# cp -p /package/admin/runit/etc/openbsd/getty-ttyC4/run \
/etc/runit/getty-5/
FreeBSD 4.4:
# cp -p /package/admin/runit/etc/freebsd/getty-ttyv4/run \
/etc/runit/getty-5/
</pre>
and tell
<a href="http://cr.yp.to/daemontools/svscan.html">svscan</a>
about the <tt>getty-5</tt> <i>service</i>:
<pre>
# ln -s /etc/runit/getty-5 /service/
</pre>
<h3>Step 4: Replace the <tt>/sbin/init</tt> binary</h3>
Before replacing the <tt>init</tt> binary, make sure that you are able
to boot your system alternatively, e.g. with a boot floppy, to restore the
former <tt>/sbin/init</tt> if anything goes wrong.
<p>
Make a backup copy of the current <tt>/sbin/init</tt> program and replace
it with <tt>/sbin/runit-init</tt>:
<pre>
# cp -p /sbin/init /sbin/init.bsd
# install /sbin/runit-init /sbin/init
</pre>
Boot your system with <i>runit</i> for the first time:
<pre>
# reboot
</pre>
Watch the console output while <i>runit</i> 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.
<p>
Use <b>init 6</b> to reboot and <b>init 0</b> to halt a system that runs
<i>runit</i>. This will cause <i>runit</i> to enter stage 3 which runs
<tt>/sbin/reboot</tt> or <tt>/sbin/halt</tt> as last command.
<p>
To report success:
<pre>
# ( uname -a ; cat /etc/runit/[123] ) | mail pape-runit-0.9.1@smarden.org
</pre>
<h3>Step 5: Service migration</h3>
The goal is to migrate all services from <i>/etc/rc.*</i> scheme to the
<a href="http://cr.yp.to/daemontools.html">daemontools</a> design; take a
look at these <a href="runscripts.html">run scripts</a> for popular
services. The migration can be done smoothly. By default <i>runit</i>
runs the <tt>/etc/rc</tt> scripts in stage 1 as a one time task, so the
services are started automatically:
<pre>
#!/bin/sh
# system one time tasks
rm -f /etc/runit/stopit
/bin/sh /etc/rc autoboot
exit 0
</pre>
To migrate a service, create a service directory, disable the service if
it is running, disable the service in <tt>/etc/rc.conf</tt> or remove the
service startup from the <tt>/etc/rc.*</tt> scripts and tell
<a href="runsvdir.8.html">runsvdir</a> about the new service.
<hr>
<address><a href="mailto:pape@smarden.org">
Gerrit Pape <pape@smarden.org>
</a></address>
<small>$Id$</small>
</body>
</html>
|
