Editing Slackware template creation

This page is about making a template cache for OpenVZ [[container]] from Slackware linux.
(This method was used for creating the minimal cache from Slackware 10.2)
The method is basically the same as described in article [[Debian template creation]].

== Getting a Slackware root filesystem ==

=== Downloading and installing Slackware ===

First you need to download Slackware linux from [http://www.slackware.org/getslack/ http://www.slackware.org/getslack/]. Then you have to [http://www.slackware.org/install/ install] it to some hardware you can spare while the cache creation process is going on. For [[container]] creation it is recommended not to install any unnecessary software into the box you are making the cache from.
This means for a minimal Slackware 10.2 cache I have chosen only series A (<tt>Base Linux System</tt>) at the package series selection screen of Slackware Setup. Then '''expert''' prompting mode on the next screen. On the Series A package selection screen I chose the following packages:

* kernel-ide <i>- This is requied to boot the OS to be able to get it's root filesystem</i>
* aaa_base
* aaa_elflibs
* bash
* bin
* bzip2
* coreutils
* cxxlibs
* dcron
* devs
* e2fsprogs <i>- This is not really needed for a container, but let him install it</i>
* elvis
* etc
* gawk
* glibc-solibs
* grep
* gzip
* kernel-modules <i>- This is needed for the first boot only as kernel-ide</i>
* less
* lilo <i>- For first boot only too</i>
* logrotate
* module-init-tools
* openssl-solibs
* pkgtools
* procps
* sed
* shadow
* sysklogd
* sysvinit
* tar
* udev
* util-linux

After selecting these packages just install the kernel and lilo, you are ready to run Slackware!

=== Configuring Slackware for acting as a container ===

Now that you have a running minimal Slackware installation, You can begin to prepare it to be
a template for a [[container]]. First you need some additional packages, 7 exactly:

{| class="wikitable"
|+ '''List of additional packages'''
! Package !! Directory of installation media to take the package from
|-
| groff-1.19.1-i486-3.tgz || slackware/ap
|-
| man-1.5p-i486-1.tgz || slackware/ap
|-
| quota-3.12-i486-1.tgz || slackware/ap
|-
| iptables-1.3.3-i486-1.tgz || slackware/n
|-
| openssh-4.2p1-i486-1.tgz || slackware/n
|-
| tcpip-0.17-i486-35.tgz || slackware/n
|-
| whois-4.6.16-i486-1.tgz || slackware/n
|}
You can install these packages issuing the following command:
<pre>
installpkg <packagename>
</pre>

After these steps, you are ready to move your Slackware installation into a [[container]].

=== Moving a Slackware installation into a container ===

I did it by compressing the whole filesystem into a tgz file and copying it to the host running OpenVZ.

Compressing it is easy:
<pre>
tar --numeric-owner -czf /slackware.tgz --exclude /slackware.tgz /
</pre>

But to copy it, you need to setup a network device on the slackware system (use <tt>ifconfig</tt> and <tt>ftp</tt>) or manually remove the hard drive containing the Slackware installation and copy the tgz file from there.

After you got the tgz file on the host, make a new directory into <tt>/vz/private</tt> with a new CTID, ''for example'' 777.
Uncompress the tgz file into this directory and remove the tgz.
<pre>
mv slackware.tgz /vz/private/777
cd /vz/private/777
gunzip -dc slackware.tgz |tar -xvf -
rm /vz/private/777/slackware.tgz
</pre>

== Preparing the new container ==

=== Creating container config ===

Now you need to create the configuration file for the [[container]], 777.conf:

<pre>
vzctl set 777 --applyconfig vps.basic --save
</pre>

=== Getting the filesystem ready to run in a container ===

Now you need to make some minor alterations under the /vz/private/777 directory.

==== Delete the directory /lost+found, clean /boot, /tmp, and /var/mail and make /proc ====
<pre>
rm -r /vz/private/777/lost+found
rm /vz/private/777/boot/*
rm /vz/private/777/tmp/*
rm /vz/private/777/var/mail/*
mkdir /vz/private/777/proc
</pre>

==== Delete the kernel modules from /lib/modules ====
<pre>
rm -r /vz/private/777/lib/modules
</pre>

==== Make a home directory for root, readable only by him ====
<pre>
mkdir /vz/private/777/root
chmod 0700 /vz/private/777/root
</pre>

==== Delete all keys from /etc/ssh ====
<pre>
rm /vz/private/777/etc/ssh/*key*
</pre>
This will ensure that a unique ssh key is generated for every single [[container]] at the first boot.
Edit ssh_config and sshd_config here if you want.

==== Delete the file /etc/mtab and make it a symlink to /proc/mounts. ====
<pre>
rm /vz/private/777/etc/mtab
ln -s /proc/mounts /vz/private/777/etc/mtab
</pre>

==== Clean the /etc/fstab file ====
<pre>
echo -n > /vz/private/777/etc/fstab
</pre>

==== Edit /etc/inittab ====

Edit /vz/private/777/etc/inittab, put a hashmark (#) before the lines containing:
<pre>
c?:1235:respawn:/sbin/agetty 38400 tty? linux
</pre>
This will prevent linux gettys to spawn.

==== Edit /etc/shadow ====

Edit <tt>/vz/private/777/etc/shadow</tt>, change root's password in the first line to an exclamation mark (<tt>!</tt>):
<pre>
root:!:13305:0:::::
</pre>
This will disable the root login until the password changed with <tt>vzctl set CTID --userpasswd root:xxx</tt>.

==== Edit /etc/rc.d/rc.S ====

Edit <tt>/vz/private/777/etc/rc.d/rc.S</tt>, putting a hashmark (<tt>#</tt>) as the first character of the line containing:
<pre>
/bin/rm -f /etc/mtab*
</pre>
This should be line 162 (239 - slackware 13.1). This will forbid Slackware to delete our symlink at every reboot.

==== Edit /etc/rc.d/rc.syslog ====

Edit <tt>/vz/private/777/etc/rc.d/rc.syslog</tt> file, put a hashmark (<tt>#</tt>) before the lines containing
<pre>
sleep 1
echo "/usr/bin/klogd -c 3 -x"
/usr/bin/klogd -c 3 -x
killall klogd 2> /dev/null
</pre>
These should be lines 11, 12, 15 and 21. This will prevent <tt>klogd</tt> (which is usually not needed) from starting at boot time.

Slackware 13.1 (12.0 and newest)
<pre>
chmod -x /vz/private/777/etc/rc.d/rc.syslog
</pre>

{{Note|if you are going to use iptables rules inside your Slackware containers which will do logging (i.e. the ones with the <tt>LOG</tt> target), you should not disable <tt>klogd</tt>.}}

== Testing the new container and making a cache file ==

=== Testing the new container ===

To test the new [[container]], simply start it:
<pre>
vzctl start 777
</pre>
If you did everything all right (and this article is correct) your new Slackware [[container]] will boot.

If the container booted, and you can enter/ssh to it, then stop it:
<pre>
vzctl stop 777
</pre>

=== Making a cache file ===

Now make a .tar.gz out of the [[container]]:
<pre>
tar czf /vz/template/cache/slackware-10.2-i486-minimal.tar.gz /vz/private/777/
</pre>

== Testing the new cache file ==

To test the the new cache file, issue:
<pre>
vzctl create 555 --ostemplate slackware-10.2-i486-minimal --ipadd x.x.x.x --hostname testy
</pre>

If created successfully, try to start it:
<pre>
vzctl start 555
</pre>
If it started, and you can ssh in, congratulations, you've got a working slackware template!

== Notice: IPtables ==
If you need to use IPtables <u>inside</u> the VE, you will have to copy the IPtables modules of your running kernel into the VE (/lib/modules directory).
This can be automatized, but every VE needs to be updated when the kernel changes.

[[Category: HOWTO]]
[[Category: Templates]]