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Ondřej Surý <ondrej@debian.org>
   postfix-policyd

Dependency based boot sequence

It is possible to converting Debian to order the boot sequence using the LSB headers in the init.d scripts. This will get rid of several bugs in the current boot sequence, and make it easier to keep the sequence correct.

The feature [http://lists.debian.org/debian-devel-announce/2008/01/msg00004.html was announced on debian-devel-announce] 2008-01-17. A [http://lists.debian.org/debian-devel-announce/2008/03/msg00011.html status update message] was sent 2008-03-16.

A new [:LSBInitScripts/DependencyBasedBoot/200805-status:status update message] is being worked on.

Advantages

Did you every need to insert a init.d scripts Y before init.d scripts Z and after init.d script X, where both Z and X is started using boot sequence number 20 (as in 20X and 20Z)? Adding your script as 20Y would not cut it, because you need Z to start before X. To do this, in Debian you currently need to talk to the maintainer of packages with scripts Z and X, asking one of them (or both) to move their script into a different number. Dependency based boot sequencing make it possible for each package maintainer to specify the dependencies of its scripts, and leave the number allocation to the dependency resolver.

Example of such problems

Status

This page is created to keep track of the state of this feature, to make it easier to coordinate an effort to implement it for Debian Lenny. It is [http://lists.debian.org/debian-release/2007/06/msg00164.html proposed] as a [http://release.debian.org/lenny-goals.txt release goal] for Lenny.

2007-07-03

2007-07-22

2007-08-08

2007-09-06

2007-10-24

2007-11-14

2007-11-29

2007-12-22

2007-12-30

2008-01-06

2008-01-14

2008-01-26

2008-02-03

2008-02-08

2008-02-20

2008-02-23

2008-03-07

2008-03-09

2008-03-13

2008-03-19

2008-04-16

2008-05-01

2008-05-18

packages with init.d scripts

843

843

845

849

855

852

851

857

860

863

863

864

863

863

866

866

873

873

873

873

873

873

873

fraction with LSB headers

56%

57%

58%

60%

62%

63%

64%

66%

67%

68%

69%

70%

73%

73%

76%

77%

78%

79%

80%

83%

98%

99%

99%

packages without LSB headers

373

363

353

336

325

319

303

292

287

280

269

258

237

229

212

203

187

181

172

148

16

12

9

base packages without LSB headers

2 of 40

1 of 40 (1 of 12 pkgs)

0 of 38 (0 of 10 pkgs)

0

0

0

0

0

0

0

0

0

0

0

0

0

desktop packages without LSB headers

6 of 58

7 of 70 (7 of 39 pkgs)

4 of 75 (4 of 42 pkgs)

0

A number of [http://bugs.debian.org/cgi-bin/pkgreport.cgi?usertag=initscripts-ng-devel@lists.alioth.debian.org&dist=unstable bug reports] are submitted to request LSB headers in init.d scripts. It is useful to track [http://bugs.debian.org/cgi-bin/pkgreport.cgi?usertag=initscripts-ng-devel@lists.alioth.debian.org&dist=testing the ones open in testing] as well.

Known issues

  • It is not possible to migrate between exim and postfix without purging the other package, due to conflicting provides.
  • Some scripts provide the same service, and this confuses insserv. Some of the scripts are scripts that have been removed from their package, but not properly removed from disk. This make insserv refuse to install these init.d scripts and thus the package fail to install when dependency based boot sequencing is enabled.
  • [http://bugs.debian.org/458582 A bug in insserv] make it report a dependency loop when there really isn't one. It happen when the combined dependency tree for both the start and stop sequence have a loop, but none of them have it individually.

  • Some init.d scripts have buggy headers, making them fail to install properly in the boot sequence.

To see the boot and reboot sequence dependecy graph, use

aptitude install insserv graphviz
/usr/share/insserv/check-initd-order -g > boot.dot
/usr/share/insserv/check-initd-order -g -k > reboot.dot
dotty boot.dot
dotty reboot.dot

The number of packages with init.d scripts was counted using apt-file update && apt-file search etc/init.d|cut -d: -f1|sort -u|wc -l in Debian/Sid. The number of packages missing LSB headers are fetched from [http://lintian.debian.org/reports/tags.html the lintian reports] for the [http://lintian.debian.org/reports/Tinit.d-script-missing-lsb-section.html init.d-script-missing-lsb-section] tag. The number of base and desktop packages missing headers were counted by creating chroots with debootstrap and tasksel.

To enable dependency based boot, the [http://packages.qa.debian.org/i/insserv.html insserv] package can be used. At [http://user.skolelinux.no/~pere/mypapers/200706-bootseq/200706-bootseq.html debconf7] and [http://www.hungry.com/~pere/mypapers/200802-bootsequence/200802-bootsequence.html FOSDEM 2008] ([http://meetings-archive.debian.net/pub/debian-meetings/2008/fosdem/ogg_theora/384x288/Reordering_the_Debian_boot_sequence_for_correctness_and_speed___Petter_Reinholdtsen.ogg video]), Petter Reinholdtsen gave a talk about the dependency based boot system. To enable it, install the insserv package and activate it like this:

aptitude install insserv && dpkg-reconfigure insserv

Make sure to use insserv version 1.09.0-6 or higher.

To usertag related bugs, send an email to request (at) bugs.debian.org, with content like this:

user initscripts-ng-devel (at) lists.alioth.debian.org
usertag 361054 + incorrect-dependency
usertag 361358 + missing-dependency
thanks

Packages left to fix

Generated using dd-list $(lynx -nolist -dump http://lintian.debian.org/reports/tags/init.d-script-missing-lsb-section.html | grep binary | cut -d" " -f1 | sort)

Daniel Baumann <daniel@debian.org>
   ipmasq

Debian Nagios Maintainer Group <pkg-nagios-devel@lists.alioth.debian.org>
   nsca

sean finney <seanius@debian.org>
   nsca (U)

Matthias Klose <doko@debian.org>
   buildbot

Jaakko Niemi <liiwi@debian.org>
   sfs

Cajus Pollmeier <cajus@debian.org>
   nsca (U)


CategoryDeveloper