Differences between revisions 140 and 141
Revision 140 as of 2011-03-01 16:59:36
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Editor: ?PeterEisentraut
Comment: dbus >=1.4.0 now available in testing
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Editor: ?PeterEisentraut
Comment: update testing status of some packages
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|| dbus || (>=1.4.0-1) || unstable || supports socket activation ||
|| rsyslog || (>=5.7.1-1) || unstable || supports socket activation, run ''systemctl enable rsyslog.service'' ||
|| hal || (>=0.5.14-4) || unstable || supports D-Bus activation ||
|| consolekit || (>=0.4.3-1) || unstable || supports D-Bus activation ||
|| avahi || (>=0.6.28-1) || unstable || avahi-daemon: supports socket and D-Bus activation, avahi-dnsconfd: started by multi-user.target. Run ''systemctl enable avahi-daemon.service'' resp. ''systemctl enable avahi-dnsconfd.service''. ||
|| dbus || (>=1.4.0-1) || testing || supports socket activation ||
|| rsyslog || (>=5.7.1-1) || testing || supports socket activation, run ''systemctl enable rsyslog.service'' ||
|| hal || (>=0.5.14-4) || testing || supports D-Bus activation ||
|| consolekit || (>=0.4.3-1) || testing || supports D-Bus activation ||
|| avahi-daemon || (>=0.6.28-1) || testing || avahi-daemon: supports socket and D-Bus activation, avahi-dnsconfd: started by multi-user.target. Run ''systemctl enable avahi-daemon.service'' resp. ''systemctl enable avahi-dnsconfd.service''. ||
Line 43: Line 43:
|| udev || (>=165-1) || unstable || enabled by default, started via basic.target ||
|| rtkit || (>=0.9-3) || unstable || supports D-Bus activation ||
|| udev || (>=165-1) || testing || enabled by default, started via basic.target ||
|| rtkit || (>=0.9-3) || testing || supports D-Bus activation ||

Translation(s): none


systemd - system and service manager

Introduction

systemd is a system and service manager for Linux, compatible with SysV and LSB init scripts. systemd provides aggressive parallelization capabilities, uses socket and D-Bus activation for starting services, offers on-demand starting of daemons, keeps track of processes using Linux cgroups, supports snapshotting and restoring of the system state, maintains mount and automount points and implements an elaborate transactional dependency-based service control logic. It can work as a drop-in replacement for sysvinit.

Installation

Currently v17 is available from experimental. systemd requires latest upstream version of dbus, means you need dbus >=1.4.0, which can be found in testing/wheezy. You have to enhance your sources.list and add experimental Distribution.

To install systemd from experimental:

# apt-get update
# apt-get install -t experimental systemd

You also need a kernel with the following options enabled:

  • CONFIG_DEVTMPFS=y
  • CONFIG_CGROUPS=y
  • CONFIG_AUTOFS4_FS=[y|m]
  • CONFIG_IPV6=[y|m], optional, but highly recommended
  • CONFIG_FANOTIFY=y, optional, required for systemd readahed. availabe in Linux kernel >= 2.6.37-rcX. Needs to be enabled for the Debian Linux kernel (605636).

Since v8 the cgroupfs is mounted at /sys/fs/cgroup. This requires a Linux kernel >= 2.6.36 or a backport of this patch.

Debian Linux kernels (>= 2.6.32-23) are suitable.

Debian packages with native systemd support

dbus

(>=1.4.0-1)

testing

supports socket activation

rsyslog

(>=5.7.1-1)

testing

supports socket activation, run systemctl enable rsyslog.service

hal

(>=0.5.14-4)

testing

supports D-Bus activation

consolekit

(>=0.4.3-1)

testing

supports D-Bus activation

avahi-daemon

(>=0.6.28-1)

testing

avahi-daemon: supports socket and D-Bus activation, avahi-dnsconfd: started by multi-user.target. Run systemctl enable avahi-daemon.service resp. systemctl enable avahi-dnsconfd.service.

network-manager

(>=0.8.2-3)

unstable

supports D-Bus activation, run systemctl enable NetworkManager.service

udev

(>=165-1)

testing

enabled by default, started via basic.target

rtkit

(>=0.9-3)

testing

supports D-Bus activation

EXAMPLE (here for rsyslog, enable service after installation from Debian/experimental):

# systemctl enable rsyslog.service
Output:
ln -s '/lib/systemd/system/rsyslog.service' '/etc/systemd/system/multi-user.target.wants/rsyslog.service'
ln -s '/lib/systemd/system/rsyslog.socket' '/etc/systemd/system/sockets.target.wants/rsyslog.socket'

Known Issues and Workarounds

Issue #1: sysvinit vs. systemd-sysv

sysvinit is the current default init-system in Debian and is flagged as an "Essential" package. This means the package management tools will refuse to remove or replace the package unless forced. Also on dist-upgrades essential packages are preferred and will be re-installed. For more Details see chapters "3.8 Essential packages" and "5.6.9 Essential"

The systemd-sysvinit package ships /sbin/init (as a symlink to /bin/systemd) and therefore conflicts with the sysvinit package.

Workaround #1: Do not install systemd-sysv, enhance grub-line (Kernel command line) by "init=/bin/systemd". For a grub2 persistent solution (requires an update-grub to refresh /boot/grub/grub.cfg):

# $EDITOR /etc/default/grub
GRUB_CMDLINE_LINUX_DEFAULT="quiet init=/bin/systemd" <--- Change this line

# update-grub

Workaround #2: Install systemd-sysv and put package "on hold".

The problem with "Essential flag" needs some discussion with the sysvinit maintainer.

This issue is only a warning and can be ignored, we have it on TODO (see below "Make /etc/mtab a symlink to /proc/self/mounts. Requires a newer util-linux package which stores user options separately."). (494001)

The full error-message in dmesg:

[    5.784886] systemd[1]: /etc/mtab is not a symlink or not pointing to /proc/self/mounts. This is not supported anymore. Please make sure to replace this file by a symlink to avoid incorrect or misleading mount(8) output.

Workaround: 1. Create required symlink 2. Mask mtab and udev-mtab services (see also initscripts: /etc/init.d/mtab.sh and /etc/init.d/udev-mtab)

# ln -sf /proc/self/mounts /etc/mtab
# ls -l /etc/mtab
Output:
lrwxrwxrwx 1 root root 17 23. Nov 11:31 /etc/mtab -> /proc/self/mounts <--- Created new symlink

# ln -s /dev/null /etc/systemd/system/mtab.service      <--- Mask mtab.service
# ln -s /dev/null /etc/systemd/system/udev-mtab.service <--- Mask udev-mtab.service

Issue #3: Unsupported fsck -l option in Debian's util-linux

In systemd there are 3 fsck to be considered and have to work together. The fsck binary from util-linux(-ng) package which is a wrapper to the diverse fsck.$FS-Type (for example: fsck.ext4) binaries from e2fsprogs package. Last but not least systemd has its own systemd-fsck implementation. The fsck binary in Debian's util-linux has no support for "-l option", so -l is passed to the fsck.ext4 binary from e2fsprogs which requires "-l filename" (see also e2fsck(8)). This results in systemd-fsck error-code #16 and ending in maintenance mode.

Until the Debian util-linux package has been updated (608120) the Debian systemd package ships a patch to revert this commit "fsck: add new -l switch to fsck mount options".

Issue #4: Dependency cycle in portmap/nfs-common

The nfs-common/portmap SysV init scripts have a dependency cycle which will cause systemd to drop them. You will get an error message during boot like the following:

Found ordering cycle path on basic.target/start
Walked on cycle path to sysinit.target/start
Walked on cycle path to portmap.service/start
Walked on cycle path to basic.target/start
Breaking ordering cycle by deleting job portmap.service

Until the portmap/nfs-common init scripts have been fixed, you can get rid of those error messages by uninstalling those packages.

Native mount

With v12 or later you can use native (means systemd's) mount and fsck facility by making sure it is activated in /etc/systemd/system.conf.

# egrep 'MountAuto|SwapAuto' /etc/systemd/system.conf
Output:
MountAuto=yes
SwapAuto=yes

The Debian package enables native mount by default since version 15-1.

If you use Logical-Volume-Manager (LVM) make sure to upgrade your lvm2 package to the latest version available from unstable (>= 2.02.84-1) as it contains important fixes regarding the udev integration. See 603710 for more details.

Debugging systemd

Sometimes it is necessary to investigate why systemd hangs on startup or on reboot/shutdown.

EXAMPLE:

  • When building a first v15 package a lot of people fell into the "fsck -l pitfall" (see Known Issues #3). Result: systemd-fsck gave back error-code #16 and got into maintenance mode (yay!).

Solution #0: Remove "quiet" from Kernel command line (so called "cmdline" or "grub line")

Solution #1: Increase verbosity via cmdline: Add "systemd.log_target=kmsg systemd.log_level=debug"

Of course you can have a "temporary" persistent solution:

[ /etc/default/grub ]
GRUB_CMDLINE_LINUX="systemd.log_target=kmsg systemd.log_level=debug" <--- Add here (by uncommenting you can easily switch to debug)

# update-grub

In addition enhance cmdline with "systemd.sysv_console=1" (0: disabled, 1: enabled).

Solution #2: Increase verbosity via /etc/systemd/system.conf

LogLevel=debug           <--- Uncomment this line and use "debug" (default: commented and "info")
LogTarget=syslog-or-kmsg <--- Uncomment this line (default: commented)
SysVConsole=yes          <--- Uncomment this line (default: commented)

HINT: "man system" and "man systemd.conf" (Note: File is system.conf vs. man-page system*d*.conf)

HINT: How to check Kernel command line parameters/options?

# cat /proc/cmdline

NOTE on ?LogLevel (see systemd(1) and systemd.conf(5)):

"Set log level. As argument this accepts a numerical log level or the well-known syslog(3) symbolic names (lowercase): emerg, alert, crit, err, warning, notice, info, debug."

HINT: Keep a copy of /sbin/init from sysvinit package in case of rescue (so you can use init=/sbin/init.sysvinit in cmdline)!

# cp -av /sbin/init /sbin/init.sysvinit <--- Before installing systemd-sysv package

Bugs and Bug-Tracking-Systems

TODO

  • Update more packages to ship systemd service files.
  • Draft a packaging policy involving systemd (upgrade / install / removal).
  • Provide integration for package maintainer tools: "dh_systemd"
  • invoke-rc.d/update-rc.d/service integration.
  • Get Essential flag removed from sysvinit.
  • Sort out what to do about pam_loginuid, and integration into the Debian PAM stack
  • Decide what to do about group:lock (/var/lock).
  • Make /etc/mtab a symlink to /proc/self/mounts. Requires a newer util-linux package which stores user options separately.
  • Make systemd-vconsole work. Investigate which of the console-* and kbd* packages are actually required and how to migrate the configuration.
  • Migration of /etc/inittab settings.
  • Collaborative work: Check the whiteboard

  • Make /lib/init/rw a symlink to /var/run. For that to work, /var/run needs to be available early, even when /var is on a separate partition. Ubuntu uses a "showthrough" mount option, which is implemented in mountall using mount --bind and --move.

WorkInProgress

  • Test cryptsetup support.

DONE

Future plans

  • Communication channels: alioth project (+ mailing list) and/or a #debian-systemd IRC channel on OFTC
  • Announcement to the Debian mailing-lists: 1. Inform there is sth. awesome 2. Join the systemd party (use it and report, contribute to packaging or even upstream)

Where to get help?

As systemd is a very young project (see [1]), we would appreciate to use the existing upstream infrastructure like mailing-list [2], IRC and read Lennart's blog [3], etc. for following the development. Most people interested in systemd development (from diverse distributions) and Debian-specific packaging are around on IRC: #systemd (irc.freenode.net). Anyway, Debian-specific bugs should be sent to Debian-BTS (for example use report-bug tool).

  1. http://0pointer.de/blog/projects/systemd.html

  2. http://lists.freedesktop.org/mailman/listinfo/systemd-devel

  3. http://0pointer.de/blog/

Who is who?

Maintainer of the systemd package is Tollef Fog Heen (Mithrandir). Currently, it's discussed to get Michael Biebl (mbiebl) as co-maintainer. Michael and Sedat Dilek (dileks) contributed to the initial version of this wiki.

Resources

References