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<h2>0compile: Chroot Build</h2>
<p>
This page explains how to build in a "chroot" sandbox environment <a href='0compile.html'>using 0compile</a>.
It offers a few advantages:
</p>
<ul>
<li>Building doesn't affect the host environment, and the host doesn't influence the build.</li>
<li>Builds can target a different architecture, such as building <i>x</i>86 packages from a <i>x</i>64 host.</li>
<li>The build sandbox is smaller than a virtual machine, and the download is typically smaller.</li>
</ul>
<p>
The build system ("chroot") comes with development tools such as gcc and make, and the <b>0launch</b> command.
</p>
<h2>Contents</h2>
<toc level='h2'/>
<h2>Chroot setup</h2>
<p>Alternatives:</p>
<ol>
<li>Build on a <a href='#debian'>Debian system</a> (including Ubuntu), using APT and .deb with <b>pbuilder</b></li>
<li>Build on a <a href='#redhat'>Red Hat system</a> (including Fedora), using Yum and .rpm with <b>mock</b></li>
<li>Build on a <a href='#lfs'>Linux From Scratch</a> system, using only source tarballs with <b>chroot</b></li>
</ol>
<p>
For all systems we use a "build" directory, that is bind-mounted inside the chroot, to hold our build results.
</p>
<dl>
<dt id='debian'>Debian / Ubuntu</dt>
<dd>
<p>
<a href="http://pbuilder.alioth.debian.org/">http://pbuilder.alioth.debian.org/</a></p>
<p>
Install and configure the software:</p>
<pre>
$ <b>sudo apt-get install pbuilder</b>
$ mkdir -p build
$ echo "BINDMOUNTS='build'" >> /etc/pbuilderrc
</pre>
<p>
Prepare the build environment cache:</p>
<pre>
MIRROR=http://ftp.debian.org/debian/
DIST=lenny
ARCH=i386 # or amd64
CPU=i486 # or x86_64
BASEDIR=/var/cache/pbuilder
TGZ=${BASEDIR}/${DIST}-${ARCH}.tgz
$ <b>sudo pbuilder --create --basetgz $TGZ --mirror $MIRROR \
--distribution $DIST --architecture $ARCH \
--extrapackages "zeroinstall-injector"</b>
</pre>
<p>
Enter the build environment chroot:</p>
<pre>
$ <b>setarch $CPU sudo pbuilder --login --basetgz $TGZ</b>
# cat /etc/debian_version
5.0.8
# 0launch --version
0launch (zero-install) 0.34
Copyright (C) 2007 Thomas Leonard
...
</pre>
<p>
Has <tt>build-essential</tt> dependencies:</p>
<ul style='font-size:0.75em'>
<li>dpkg-dev
<ul>
<li>dpkg</li>
<li>perl5</li>
<li>perl-modules</li>
<li>cpio</li>
<li>bzip2</li>
<li>lzma</li>
<li>patch</li>
<li>make</li>
<li>binutils</li>
<li>libtimedate-perl</li>
<li>gcc | c-compiler</li>
</ul></li>
<li>g++</li>
<li>libc6-dev | libc-dev</li>
<li>make</li>
</ul>
</dd>
<dt id='redhat'>Red Hat / Fedora</dt>
<dd>
<p>
<a href="https://fedorahosted.org/mock/">https://fedorahosted.org/mock/</a></p>
<p>
Install and configure the software:</p>
<pre>
$ <b>su -c "yum install mock"</b>
$ <b>su -c "usermod -G mock $USER"</b>
$ mkdir -p build
$ echo "config_opts['plugin_conf']['bind_mount_opts']['dirs']\
.append(('./build', '/build'))" >> /etc/mock/site-defaults.cfg
</pre>
<p>
Prepare the build environment cache:</p>
<pre>
ARCH=i386 # or x86_64
ROOT=epel-5-$ARCH
$ <b>mock --root=$ROOT --arch=$ARCH --init</b>
$ <b>mock --root=$ROOT --arch=$ARCH --install "zeroinstall-injector"</b>
</pre>
<p>
Enter the build environment chroot:</p>
<pre>
$ <b>mock --root=$ROOT --arch=$ARCH --shell</b>
> cat /etc/redhat-release
CentOS release 5.6 (Final)
> 0launch --version
0launch (zero-install) 0.38
Copyright (C) 2007 Thomas Leonard
...
$ <b>mock --root=$ROOT --arch=$ARCH --clean</b>
</pre>
<p>
Has <tt>buildsys-build</tt> dependencies:</p>
<ul style='font-size:0.75em'>
<li>bash</li>
<li>buildsys-macros</li>
<li>bzip2</li>
<li>coreutils</li>
<li>cpio</li>
<li>diffutils</li>
<li>elfutils</li>
<li>gcc-c++</li>
<li>gcc</li>
<li>gzip</li>
<li>make</li>
<li>patch</li>
<li>perl</li>
<li>redhat-release</li>
<li>redhat-rpm-config</li>
<li>rpm-build</li>
<li>sed</li>
<li>tar</li>
<li>unzip</li>
<li>which</li>
</ul>
</dd>
<dt id='lfs'>Linux From Scratch</dt>
<dd>
<p>
<a href="http://www.linuxfromscratch.org/lfs/">http://www.linuxfromscratch.org/lfs/</a></p>
<p>Build LFS:</p>
<ul>
<li><a href='http://www.linuxfromscratch.org/lfs/view/stable/'>Read the Linux From Scratch Book</a></li>
</ul>
<p>Enter chroot:</p>
<blockquote>
<pre>
export LFS=/mnt/lfs
sudo mount -v --bind /dev $LFS/dev
sudo mount -vt devpts devpts $LFS/dev/pts
sudo mount -vt tmpfs shm $LFS/dev/shm
sudo mount -vt proc proc $LFS/proc
sudo mount -vt sysfs sysfs $LFS/sys
sudo mkdir -pv $LFS/build
sudo mount -v --bind ./build $LFS/build
$ <b>sudo chroot $LFS /usr/bin/env -i \
HOME=/root TERM="$TERM" PS1='\u:\w\$ ' \
PATH=/bin:/usr/bin:/sbin:/usr/sbin \
/bin/bash --login</b>
# cat /etc/lfs-release
6.8
</pre>
</blockquote>
<p>BLFS packages:</p>
<ul>
<li><a href='http://www.linuxfromscratch.org/blfs/view/svn/postlfs/openssl.html'>OpenSSL</a> (Python dependency)</li>
<li><a href='http://www.linuxfromscratch.org/blfs/view/svn/general/python.html'>Python</a></li>
<li><a href='http://www.linuxfromscratch.org/blfs/view/svn/postlfs/gnupg.html'>GnuPG</a></li>
<li><a href='http://www.linuxfromscratch.org/blfs/view/svn/general/pcre.html'>PCRE</a> (Glib dependency)</li>
<li><a href='http://www.linuxfromscratch.org/blfs/view/svn/general/glib2.html'>GLib</a> (PyGObject dependency)</li>
<li><a href='http://www.linuxfromscratch.org/blfs/view/svn/general/python-modules.html#pygobject'>PyGObject</a></li>
</ul>
<p>Zero Install itself:</p>
<ul>
<li><a href='http://0install.net/install-source.html'>ZeroInstall-Injector</a></li>
</ul>
</dd>
</dl>
<h2>0compile setup</h2>
<p>
Now we have a chroot with <b>0launch</b>, and can add <b>0compile</b>:</p>
<pre>
CMD="0compile"
URI="http://0install.net/2006/interfaces/0compile.xml"
$ yes Y | /usr/bin/0launch -cd $URI
$ 0alias -d /usr/bin $CMD $URI
</pre>
<p>
Note: depending on your build OS and Python version,
you might need to use an older version of 0compile.</p>
<h2>0compile build</h2>
<p>
Begin with downloading the source code, in console mode:</p>
<pre>
$ <b>0launch -cd -s <i>http://www.example.com/interfaces/foo.xml</i></b>
</pre>
<p>
Then we setup the build sub-directory using the source feed:</p>
<pre>
$ cd /build
$ <b>0compile setup <i>http://www.example.com/interfaces/foo.xml</i> <i>foo</i></b>
</pre>
<p>
Next we proceed with building the binary from the source:</p>
<pre>
$ cd <i>foo</i>
$ <b>0compile build</b>
</pre>
<p>
Finally we tell 0compile to prepare the binary feed/archive:</p>
<pre>
$ <b>0compile publish http://www.example.com/implementations</b>
</pre>
<p>
After exiting the chroot, we can find the results in build/foo.</p>
<h2>Publish results</h2>
<p>
The new binary feed is now ready to be merged with our source feed,
signed (using 0publish --xmlsign), and published with the archives.
</p>
<p>
Since we used a new clean chroot to build the binary, we can be
reasonably sure that all dependencies are included in the source feed.
</p>
<h2>Future directions</h2>
<p>
In the future it might be possible to use the
<a href='http://open-build-service.org/'>Open Build Service</a> (OBS),
to build Zero Install packages using a distributed development platform.
</p>
<p>
Currently it (OBS) supports building RPM and Debian packages, those can be
converted to Zero Install feeds using <a href='pkg2zero.html'>pkg2zero</a>
(when relocatable).
</p>
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