sbuild-setup

sbuild uses chroots to build packages within, to provide a minimal and consistent build environment. This man page describes the procedure to create a chroot by hand using debootstrap. These are only guidelines; depending upon the setup required, several of the steps may be omitted entirely.

QUICK START

Simply running sbuild-createchroot will perform all the setup steps described in detail below. See the section “ sbuild-createchroot” below, as well as sbuild-createchroot(8).

CHROOT SETUP

This guide sets up a lenny chroot on a powerpc machine. Adjust the names for other suites and architectures.

1. Run debootstrap to create the chroot

# mkdir -p /srv/chroot/lenny

The author has each chroot as a separate LVM logical volume (LV). Create and mount an LV here if required:

# lvcreate -L 4G -n lenny_chroot -Z y volume-group

Add to /etc/fstab and mount (see next section for full fstab example). Finally, run debootstrap to create the chroot:

# debootstrap --variant=buildd lenny /srv/chroot/lenny http://deb.debian.org/debian/

2. Set up additional mounts

An example /etc/fstab:

/dev/volume-group/lenny_chroot \
	/srv/chroot/lenny	ext3	defaults	0	2
/dev/pts	/srv/chroot/lenny/dev/pts	none	rw,bind	0	0
tmpfs	/srv/chroot/lenny/dev/shm	tmpfs	defaults	0	0
proc	/srv/chroot/lenny/proc	proc	defaults	0	0
/dev/volume-group/home \
	/srv/chroot/lenny/home	ext3	quota	0	0
/tmp	/srv/chroot/lenny/tmp	none	rw,bind	0	0
/etc/passwd	/srv/chroot/lenny/etc/passwd	none	ro,bind	0	0
/etc/shadow	/srv/chroot/lenny/etc/shadow	none	ro,bind	0	0
/etc/group	/srv/chroot/lenny/etc/group	none	ro,bind	0	0
/etc/gshadow	/srv/chroot/lenny/etc/gshadow	none	ro,bind	0	0
/etc/resolv.conf \
	/srv/chroot/lenny/etc/resolv.conf \
		none	ro,bind	0	0

If the bind mountpoints don't exist in the chroot, touch them:

# touch /srv/chroot/lenny/etc/resolv.conf

Next, mount them all.

Depending on your kernel version and security considerations, you may wish to do this part slightly differently. With a Linux kernel, at least version 2.6 is required for bind mounts, and devpts (CONFIG_UNIX98_PTYS) for /dev/pts. Other guides recommend copying the files, but this method keeps them up-to-date at no cost.

If using sbuild with schroot, passwd, shadow, group, gshadow and resolv.conf can be updated automatically at the start of each build, so no action is required here. schroot can also automatically mount all of the extra filesystems, so all the other mounts may be omitted.

To disable networking, don't bind mount /etc/resolv.conf. This will prevent APT from working inside the chroot, but prevents package building from having working network access (no nameservers).

3. Edit sources.list

Create or edit /srv/chroot/lenny/etc/apt/sources.list, and add all the APT sources required to obtain binary and source packages for your chosen distribution:

deb http://security.debian.org/ lenny/updates main

deb-src http://security.debian.org/ lenny/updates main

deb http://deb.debian.org/debian/ lenny main

deb-src http://deb.debian.org/debian/ lenny main

4. Configure dchroot or schroot

This is entirely optional, but will make the chroot environment easier to access and administer.

For dchroot, add the following line to /etc/dchroot.conf:

lenny /srv/chroot/lenny

For schroot, add a group to /etc/schroot/schroot.conf (or a new file /etc/schroot/chroot.d/lenny), for example:

[lenny]

type=directory

description=Debian lenny (stable)

location=/srv/chroot/lenny

priority=2

groups=root,sbuild

root-groups=sbuild

aliases=stable

run-setup-scripts=true

run-session-scripts=true

For sudo, add a symbolic link to the directory /etc/sbuild/chroot, for example:

# mkdir -p /etc/sbuild/chroot

# ln -s /srv/chroot/lenny /etc/sbuild/chroot/lenny

5. Log into chroot

# dchroot -c lenny

$ schroot -c lenny -u root

6. Set up packages for sbuild

While running as root inside the chroot:

# apt-get update

# apt-get dist-upgrade

# apt-get install debconf

# dpkg-reconfigure -plow debconf

Answer the debconf questions as follows:

interface: choose 6/Noninteractive

priority: choose 1/Critical

You only need to run dpkg-reconfigure if you weren't asked the questions during the debconf install. Next, install the packages required for building packages:

# apt-get install fakeroot build-essential

# apt-get install makedev

# cd /dev/

# /sbin/MAKEDEV generic

# touch /etc/mtab

For some security, we don't bind mount /dev, so it can't access e.g. USB devices

7. sbuild setup

While running as root inside the chroot:

# mkdir /build

# chown root:sbuild /build

# chmod 02775 /build

# mkdir -p /var/lib/sbuild/srcdep-lock

# chown -R root:sbuild /var/lib/sbuild

# chmod -R 02775 /var/lib/sbuild

Note that when using sbuild with schroot, this setup is done at the start of each build, so is not required here.

8. Finished

Congratulations! You should now have a fully configured and operational chroot.

SBUILD-CREATECHROOT

This script will automatically perform a number of the steps described above, including:

•: Running debootstrap.

•: Setting up APT sources in /etc/apt/sources.list.

•: Setting up a minimal /etc/passwd

•: Setting up /build and /var/lib/sbuild with appropriate ownership and permissions.

After it has done this, you do still need to do some manual setup, completing the steps it missed out above, for example.

USER SETUP

1. Group membership

As root, run:

# sbuild-adduser user

Alternatively, add the user to the sbuild group by hand:

# adduser user sbuild

2. ~/.sbuildrc

Configure the user's ~/.sbuildrc:

$ cp /usr/share/doc/sbuild/examples/example.sbuildrc ~user/.sbuildrc

Edit to set the correct mail address to send log files to, and the correct maintainer name and/or uploader name.

3. Build directories

Create directories to contain packages and log files. (.sbuildrc may have configured different locations; the default build directory is the current directory, and the default $log_dir is ~/logs):

$ mkdir ~/logs

4. sudo setup

This step not required if schroot is used (which is the default, set in sbuild.conf). If using sbuild with sudo (chroot_mode “split”), sudo needs configuring to give the user permission to install and remove packages in the chroot, which requires root privileges. Add the following lines to /etc/sudoers:

username ALL=NOPASSWD: ALL

Defaults: username env_keep+="APT_CONFIG DEBIAN_FRONTEND SHELL"

where username is the name of the user who will run sbuild.

sbuild-setup

NAME

DESCRIPTION