Create a LXC container in Debian Jessie without systemd

Written by Claudio Kuenzler - 0 comments

Published on March 14th 2016 - Listed in LXC Linux Systemd

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By default, a LXC container created with the "debian" template (/usr/share/lxc/templates/lxc-debian) contains the systemd init system. And even if the physical host itself doesn't run the systemd, the containers still do.

To prevent this from happening or better said to remove systemd and install another init system, the template can be slightly modified. In this example I replace systemd with the classical SysV init. Before the usage() function, I added:

nosystemd()
{
  # Based on http://without-systemd.org/wiki/index.php/How_to_remove_systemd_from_a_Debian_jessie/sid_installation

  echo "Installing SysV init and removing systemd"

  # Install SysV init
  chroot $rootfs apt-get -y --force-yes -qq install sysvinit-core sysvinit-utils
  chroot $rootfs cp /usr/share/sysvinit/inittab /etc/inittab

  # Remove SystemD
  chroot $rootfs apt-get -y --force-yes -qq remove --purge --auto-remove systemd

  # Prevent apt from installing systemd packages in the future
  echo -e 'Package: systemd\nPin: release *\nPin-Priority: -1' > $rootfs/etc/apt/preferences.d/systemd
  echo -e '\n\nPackage: *systemd*\nPin: release *\nPin-Priority: -1' >> $rootfs/etc/apt/preferences.d/systemd
}

And at the end of the template file, where the functions are launched one after another, the new function "nosystemd" is called:

install_debian $rootfs $release $arch
if [ $? -ne 0 ]; then
    echo "failed to install debian"
    exit 1
fi

configure_debian $rootfs $name
if [ $? -ne 0 ]; then
    echo "failed to configure debian for a container"
    exit 1
fi

copy_configuration $path $rootfs $name $arch
if [ $? -ne 0 ]; then
    echo "failed write configuration file"
    exit 1
fi

configure_debian_systemd $path $rootfs

# Manual modifications
nosystemd

if [ ! -z $clean ]; then
    clean || exit 1
    exit 0
fi

A created container now runs the following processes:

root@ ~ # ps auxf
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root       485  0.0  0.0  21892  3696 ?        S    21:31   0:00 /bin/bash
root       583  0.0  0.0  19096  2500 ?        R+   21:31   0:00  \_ ps auxf
root         1  0.0  0.0  15492  1812 ?        Ss   21:30   0:00 init [2] 
root       465  0.0  0.0  27476  2228 ?        Ss   21:30   0:00 /usr/sbin/cron
root       468  0.0  0.0  55180  2892 ?        Ss   21:30   0:00 /usr/sbin/sshd
root       475  0.0  0.0  12664  1868 tty1     Ss+  21:30   0:00 /sbin/getty 38400 tty1
root       476  0.0  0.0  12664  1820 tty2     Ss+  21:30   0:00 /sbin/getty 38400 tty2
root       477  0.0  0.0  12664  1856 tty3     Ss+  21:30   0:00 /sbin/getty 38400 tty3
root       478  0.0  0.0  12664  1836 tty4     Ss+  21:30   0:00 /sbin/getty 38400 tty4
root       577  0.0  0.0  12664  1748 ?        Ss   21:31   0:00 /sbin/getty 38400 tty5
root       578  0.0  0.0  12664  1860 ?        Ss   21:31   0:00 /sbin/getty 38400 tty6

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