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Comment: Updated package list.
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Clarified applicability to Jessie.
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Deletions are marked like this. | Additions are marked like this. |
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#language en ~-[[DebianWiki/EditorGuide#translation|Translation(s)]]: none-~ ---- |
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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. |
Before Debian 8.0, Debian used init to boot-up the system. This page provide information of the details to resolve the dependency issues. Since Debian 8.0, Systemd replaced init and the dependency was relied on its target files. The information described here no longer applies to Debian's default in Jessie. Debian was converted to order the boot sequence using the LSB fields in the header of each init.d script. This has removed several bugs in the former boot sequence, and now makes it easier to keep the sequence correct. |
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Did you ever 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. | |
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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. |
Some examples of such problems are DebianBug:256699 DebianBug:294053, DebianBug:279297, DebianBug:311057 and DebianBug:475626 . == How to add a service when using dependency-based booting == In Debian releases '''prior to 6.0''', a service could be added with update-rc.d: {{{ update-rc.d mydaemon defaults }}} Starting with Debian 6.0, the insserv command is used instead, if dependency-based booting is enabled: {{{ insserv mydaemon }}} Where ''mydaemon'' is an executable init script placed in /etc/init.d. insserv will produce no output if everything went OK. Examine the error code in $? if you want to be sure. Both the old and the new way requires an init script to be present in /etc/init.d. For dependency-based booting, the script needs to be an [[LSBInitScripts|LSB init script]]. As of Debian 7 [[http://manpages.debian.org/cgi-bin/man.cgi?query=insserv&apropos=0&sektion=0&manpath=Debian+7.0+wheezy&format=html&locale=en|man insserv]] states insserv is a low level tool used by update-rc.d which enables an installed system init script (`boot script') by reading the comment header of the script so you need not use it ''instead'' of update-rc.d - see your local manpage for details. == History of the feature == The feature was [[http://alioth.debian.org/docman/view.php/30730/38/debconf2-initscripts-bkg.pdf|proposed at debconf in 2002]], and has been worked on since before 2006, and [[http://lists.debian.org/debian-devel-announce/2008/01/msg00004.html|was announced on debian-devel-announce]] 2008-01-17. A status update message was sent [[http://lists.debian.org/debian-devel-announce/2008/03/msg00011.html|2008-03-16]] and [[http://lists.debian.org/debian-devel-announce/2008/11/msg00007.html|2008-11-30]]. The default in Debian was changed to dependency based boot sequencing 2009-07-27, and an updated announcement about the plans for the boot system was sent out [[http://lists.debian.org/debian-devel-announce/2009/09/msg00003.html|2009-09-05]]. The default in Debian was changed to run scripts in parallel 2010-05-14 and an announcement was sent on [[http://lists.debian.org/debian-devel-announce/2010/05/msg00009.html|2010-05-21]]. |
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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. |
This page was created to keep track of the state of this feature, to make it easier to coordinate an effort to implement it in Debian. It was [[http://lists.debian.org/debian-release/2007/06/msg00164.html|proposed]] as a [[http://release.debian.org/lenny-goals.txt|release goal]] for Lenny. It will be the default boot ordering method for Squeeze. During Debconf in 2009, the default in Sid was changed to use dependency based boot sequencing by default. |
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|| || 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 || || packages with init.d scripts || 843 || 843|| 845 || 849 || 855 || 852 || 851 || 857 || 860 || 863 || 863 || 864 || 863 || 863 || 866 || || fraction with LSB headers || 56% || 57% || 58% || 60% || 62% || 63% || 64% || 66% || 67% || 68% || 69% || 70% || 73% || 73% || 76% || || packages without LSB headers || 373 || 363|| 353 || 336 || 325 || 319 || 303 || 292 || 287 || 280 || 269 || 258 || 237 || 229 || 212 || || 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 || || desktop packages without LSB headers || 6 of 58 || || || || || 7 of 70 (7 of 39 pkgs) || || || || 4 of 75 (4 of 42 pkgs) || || || || || || |
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 fields 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. |
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With the current rate (2007-12-30) of packages being fixed to include the dependency information, it will take 410 days until all the remaining packages are fixed. Thanks to the default values provided since insserv version 1.09.0-4, most scripts get a useful start sequence position even without an LSB header. Scripts in rcS.d/ need a proper header, still. |
A daily updated archive wide check of init.d scripts is available from http://lintian.debian.org/~pere/ . [[http://piuparts.debian.org/sid/insserv_error.html|Piuparts]] now reports installation errors due to incorrect dependencies, and [[http://piuparts.debian.org/sid/initdscript_lsb_header_issue.html|inconsistencies]] between update-rc.d calls and LSB fields. |
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All packages installed by more than 0.6% (444 installations) of the population (according to popcon.debian.org) are handled 2008-01-15. | === Plan of migration === |
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A number of [http://bugs.debian.org/cgi-bin/pkgreport.cgi?usertag=initscripts-ng-devel@lists.alioth.debian.org 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. | This is a proposal for a plan to migrate all of Debian over to dependency based boot sequencing. |
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=== Known issues === | 1. Change the debconf default in DebPkg:insserv to enable dependency based boot sequencing when the package is installed, if it is safe to do so. Show the question again on upgrades if the conversion isn’t done yet. Remove/disable the option to disable DebPkg:insserv after it is enabled. 1. Change DebPkg:sysv-rc to depend on DebPkg:insserv, to pull it in on all (non-file-rc) installations. 1. Wait 6 months, while rewriting policy text to document the new way {{{update-rc.d}}} is going to work. 1. Drop support for specifying sequence numbers in {{{update-rc.d}}}. |
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* There is a real dependency loop in the init.d scripts in mysql-server-5.0. A fix [http://bugs.debian.org/458798 is proposed for this package]. | This will enable dependency based boot sequencing for all in Debian from Squeeze and onwards. |
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* It is not possible to migrate between exim and postfix without purging the other package, due to conflicting provides. | == How to solve migration problems == |
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* 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. | === package X removed but not purged === |
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* [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. | If a script in {{{/etc/init.d/}}} belongs to a package that is removed but not purged, the field is probably missing or is outdated. Purging the package will solve the issue. |
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* Some init.d scripts have buggy headers, making them fail to install properly in the boot sequence. | === package X left obsolete init.d script behind === |
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To see the boot and reboot sequence dependecy graph, use | The script was probably dropped from its package, but the package maintainer forgot to add code in the postinst to remove the obsolete script during upgrades. Removing the script is probably the correct solution. We have seen [[DebianBug:463632|one report]] where dpkg would claim that a script was obsolete one time and not obsolete one upgrade later, so this should probably be checked a bit before the script is removed. To verify that a package really left behind obsolete conffiles, one can run {{{ dpkg-query -W -f='${Conffiles}\n' packagename | grep obsolete }}} There are several reasons why these scripts are not removed automatically during upgrades. First of all, reporting these issues exposes bugs that should be fixed in the individual packages. Second, it is hard to know if the script reported was left behind for a strange and particular reason, or just forgotten. And last, there is the one report that a non-obsolete script was reported as obsolete. Still not sure if that was for real or not, but until we know the reason, it seemed risky to just remove scripts in other packages during upgrades. Besides doing so from the sysv-rc postinst would be a policy violation. === insserv: warning: script 'X' missing LSB tags and overrides === The {{{/etc/init.d/X}}} script is lacking the LSB fields. Adding them to the script header or as a override file in /etc/insserv/overrides/X would solve it. === insserv: script X: service Y already provided! === Bug in the package with script X: The facility provided in script {{{/etc/init.d/X}}} uses a non-unique value. Changing it to a unique value (for example the script name without .sh ending), solves the issue. == Common problems with init.d script header LSB fields == Here are some problems I have seen with the LSB fields in init.d scripts during the last three years. I provide it here for those of you wondering if your package’s init.d scripts are correct. 1. Non-unique Provides field When two packages have scripts with the same Provides field, it will only be able to install these packages if the init.d script of the other is not present in {{{/etc/init.d/}}}. Packages sharing a common service with other packages could use virtual facilities instead of conflicting provides, or normal dependencies if few packages are involved. 2. Incorrect runlevel list If the Default-Start and Default-Stop fields do not list the runlevels where a script should be stopped or started, the wrong set of start and stop symlinks will be created when the script is installed, and the boot and shutdown sequence will most likely be incorrect. Fixing it require both updates to the fields, and code in the postinst script to add or remove symlinks that where missing. 3. Missing dependency on {{{$syslog}}} when logging to syslog Without it, services might be started too early during boot and some syslog messages might be lost. 4. Missing dependency on {{{$remote_fs}}} when needing files in {{{/usr/}}}. Scripts starting from {{{rcS.d/}}} will start too early when {{{/usr/}}} is on NFS, and will probably fail to work because some of its expected files and programs are missing when the script starts. 5. Depending on incorrect or non-existing provides The intended relationship with another script does not take effect, making the script run too early or too late during boot and shutdown. To see the boot and reboot sequence dependency graph, use |
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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. |
The list of packages whose init.d script is lacking an LSB header can be 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. |
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To enable dependency based boot, the [http://packages.qa.debian.org/i/insserv.html insserv] package can be used. At debconf7, Petter Reinholdtsen gave a [http://user.skolelinux.no/~pere/mypapers/200706-bootseq/200706-bootseq.html talk] about the dependency based boot system. To enable it, install the insserv package and activate it like this: |
To enable dependency based boot, DebPkg:insserv 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 in older versions of Debian, install DebPkg:insserv and activate it like this: |
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aptitude install insserv && dpkg-reconfigure insserv | aptitude install insserv && dpkg-reconfigure insserv sysv-rc |
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Make sure to use insserv version 1.09.0-6 or higher. | Make sure to use DebPkg:insserv version 1.09.0-6 or higher. |
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To usertag related bugs, send an email to request (at) bugs.debian.org, with content like this: |
To usertag related bugs, send an email to request (at) bugs.debian.org, with content like this: |
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== 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 W: | cut -d" " -f2)}}} {{{ Guenter Geiger (Debian/GNU) <geiger@debian.org> realtime-lsm Stefan Hornburg (Racke) <racke@linuxia.de> courier-authlib interchange pure-ftpd sympa Cyril Lacoux (Yack) <clacoux@easter-eggs.com> digitools Marco Presi (Zufus) <zufus@debian.org> linesrv Peter De Schrijver (p2) <p2@mind.be> linux-atm Osamu Aoki <osamu@debian.org> tpconfig Ben Armstrong <synrg@sanctuary.nslug.ns.ca> xpilot-ng Don Armstrong <don@debian.org> spamass-milter SZALAY Attila <sasa@debian.org> zorp Alan Bain <afrb2@debian.org> rbootd Andreas Barth <aba@not.so.argh.org> mgetty Daniel Baumann <daniel@debian.org> ipmasq nfs-user-server Hilko Bengen <bengen@debian.org> ulog-acctd Grzegorz Bizon <verdan@pirx.int.pl> specter Blars Blarson <blarson@blars.org> cnews Ed Boraas <ed@debian.org> tinyproxy Cyril Bouthors <cyril@bouthors.org> bld drbdlinks Chris Boyle <cmb@debian.org> reaim Adrian Bridgett <bridgett@debian.org> dante Eric Van Buggenhaut <ericvb@debian.org> udhcp Bruno Barrera C. <bruno@debian.org> portsentry Patrick Caulfield <patrick@debian.org> mopd Dennis L. Clark <dbugger@debian.org> bnetd Jesus Climent <jesus.climent@hispalinux.es> distmp3 Russell Coker <russell@coker.com.au> memlockd Jamin W. Collins <jcollins@asgardsrealm.net> jabber Carlo Contavalli <ccontavalli@debian.org> wipl Paul Cupis <paul@cupis.co.uk> guarddog guidedog Artur R. Czechowski <arturcz@hell.pl> rrdcollect Julien Danjou <acid@debian.org> greylistd ledstats tetrinetx tleds Debian GNUstep maintainers <pkg-gnustep-maintainers@lists.alioth.debian.org> gnustep-base Debian Hamradio Maintainers <debian-hams@lists.debian.org> aprsd ssbd Debian Icecast team <pkg-icecast-devel@lists.alioth.debian.org> icecast2 Debian Multimedia Team <debian-multimedia@lists.debian.org> das-watchdog Debian Nagios Maintainer Group <pkg-nagios-devel@lists.alioth.debian.org> nsca Debian VoIP Team <pkg-voip-maintainers@lists.alioth.debian.org> rtpproxy siproxd Eric Delaunay <delaunay@debian.org> scsitools Bernd Eckenfels <ecki@debian.org> net-acct transproxy Robert S. Edmonds <edmonds@debian.org> pcaputils Nick Estes <debian@nickstoys.com> upsd Martín Ferrari <martin.ferrari@gmail.com> vtun Duncan Findlay <duncf@debian.org> spamassassin Turbo Fredriksson <turbo@debian.org> roxen4 Jochen Friedrich <jochen@scram.de> isakmpd Peter S Galbraith <psg@debian.org> xtide Radovan Garabik <garabik@melkor.dnp.fmph.uniba.sk> serpento Radovan Garabík <garabik@kassiopeia.juls.savba.sk> karrigell xtell Hector Garcia <hector@debian.org> smail Matthew Garrett <mjg59@srcf.ucam.org> netapplet nstx RISKO Gergely <risko@debian.org> shaperd David Gil <dgil@telefonica.net> pads John Goerzen <jgoerzen@complete.org> pygopherd Celso González <celso@bulma.net> cpudyn Daniel Gubser <guterm@debian.org> psad Guido Guenther <agx@sigxcpu.org> smartmontools Aurélien GÉRÔME <ag@roxor.cx> dancer-ircd dancer-services Marc Haber <mh+debian-packages@zugschlus.de> ifupdown-scripts-zg2 Pierre Habouzit <madcoder@debian.org> whitelister Pascal Hakim <pasc@debian.org> anacron Chris Halls <halls@debian.org> apt-proxy David B. Harris <dbharris@debian.org> ipband Andres Seco Hernandez <AndresSH@debian.org> alamin Varun Hiremath <varunhiremath@gmail.com> oss-preserve Henrique de Moraes Holschuh <hmh@debian.org> fcron rng-tools Simon Horman <horms@debian.org> heartbeat perdition Peter Howard <pjh@northern-ridge.com.au> zoneminder Qingning Huo <qhuo@mayhq.co.uk> log2mail Alberto Gonzalez Iniesta <agi@inittab.org> fwlogwatch netkit-bootparamd xmbmon Mario Iseli <admin@marioiseli.com> irmp3 Ian Jackson <ian@chiark.greenend.org.uk> sauce Ian Jackson <ian@davenant.greenend.org.uk> userv LENART Janos <ocsi@debian.org> jmon Joerg Jaspert <joerg@debian.org> muddleftpd LaMont Jones <lamont@debian.org> hpsockd Karl E. Jorgensen <karl@jorgensen.com> battery-stats Takuo KITAME <kitame@debian.org> smtpguard Bastian Kleineidam <calvin@debian.org> fiaif Matthias Klose <doko@debian.org> buildbot Steve Kowalik <stevenk@debian.org> xringd Antonin Kral <A.Kral@sh.cvut.cz> pimd Anand Kumria <wildfire@progsoc.org> tspc Joshua Kwan <joshk@triplehelix.org> nethack Mario Lang <mlang@debian.org> filterproxy Thomas Lange <lange@debian.org> fai Chris Lawrence <lawrencc@debian.org> gnome-lokkit John Lines <john@paladin.demon.co.uk> plptools smtpd Pablo Lorenzzoni <spectra@debian.org> tcpspy Ola Lundqvist <opal@debian.org> dhttpd ledcontrol nfsbooted ntop Ian Maclaine-cross <iml@debian.org> ddns3-client Keita Maehara <maehara@debian.org> freewnn Aigars Mahinovs <aigarius@debian.org> swapd Peter Makholm <peter@makholm.net> slashem Christoph Martin <christoph.martin@uni-mainz.de> mimedefang Peter Mathiasson <peterm@debian.org> pam-devperm Martin Maurer <fireflier@gibraltar.at> fireflier Brian May <bam@snoopy.debian.net> heimdal Rene Mayrhofer <rene.mayrhofer@gibraltar.at> gibraltar-bootcd Rene Mayrhofer <rmayr@debian.org> pptpd Jonathan McDowell <noodles@earth.li> l2tpns Neil McGovern <neilm@debian.org> blootbot Steve McIntyre <93sam@debian.org> nas wmaloader Michael Mende <debian@menole.net> wackamole Abraham vd Merwe <abz@debian.org> ixbiff Michael Meskes <meskes@debian.org> jftpgw Millis Miller <millis@faztek.org> iptotal Loic Minier <lool@dooz.org> termpkg Sam Morris <sam@robots.org.uk> pymsnt Sebastian Muszynski <do2ksm@linkt.de> ax25spyd Gergely Nagy <algernon@debian.org> tama Marco Nenciarini <mnencia@debian.org> xtradius Jaakko Niemi <liiwi@debian.org> sfs Recai Oktaş <roktas@debian.org> elog Masahito Omote <omote@debian.org> totd Gerrit Pape <pape@smarden.org> dropbear Eloy A. Paris <peloy@debian.org> ipxripd ncpfs Javier Fernandez-Sanguino Pen~a <jfs@debian.org> bastille Javier Fernandez-Sanguino Pen~a <jfs@computer.org> honeyd samhain VÃctor Pérez Pereira <vperez@debianvenezuela.org> squidtaild Nick Phillips <nwp@lemon-computing.com> teapop Ari Pollak <ari@debian.org> drscheme Cajus Pollmeier <cajus@debian.org> uif Daniel J. Priem <danielpriem@flexserv.de> capisuite Celso Providelo <cprov@gwyddion.com> sqcwa Puppet Package Maintainers <pkg-puppet-devel@lists.alioth.debian.org> puppet Mark Purcell <msp@debian.org> gsmlib hpoj KELEMEN Péter <fuji@debian.org> arpwatch Martin Quinson <mquinson@debian.org> nws Ganesan Rajagopal <rganesan@debian.org> ipsec-tools openslp-dfsg Kurt Roeckx <kurt@roeckx.be> ircd-irc2 Piotr Roszatycki <dexter@debian.org> ldapdns systune Mats Rynge <mats@rynge.net> p3scan Anibal Monsalve Salazar <anibal@debian.org> bpalogin pipsecd swapspace Bernd Schumacher <bernd.schumacher@hp.com> secvpn Vladimir Shakhov <lumpen.intellectual@gmail.com> wdm Guus Sliepen <guus@debian.org> inputlirc Paul Slootman <paul@debian.org> isdnutils Jonas Smedegaard <dr@jones.dk> netatalk pop-before-smtp rpld Roger So <rogerso@debian.org> im-sdk Joop Stakenborg <pa3aba@debian.org> cwdaemon pingpong Dennis Stampfer <seppy@debian.org> timeoutd Stephan A Suerken <absurd@debian.org> gom Ondřej Surý <ondrej@debian.org> bird nsd postfix-policyd Bryan Sutula <Bryan.Sutula@hp.com> openhpi Matt Taggart <taggart@debian.org> cpqarrayd Jose Luis Tallon <jltallon@adv-solutions.net> couriergraph Stuart Teasdale <sdt@debian.org> ganglia-monitor-core Paul Telford <pxt@debian.org> mordor mudnames Michael Tokarev <mjt@corpit.ru> rbldnsd Torrus maintainers <pkg-torrus-maintainers@lists.alioth.debian.org> torrus Fumitoshi UKAI <ukai@debian.or.jp> hyperestraier quickml smtpfeed Junichi Uekawa <dancer@debian.org> rarpd Utnubu Team <utnubu-maintainers@lists.alioth.debian.org> dmraid Matej Vela <vela@debian.org> vsftpd Santiago Vila <sanvila@debian.org> postfix-gld Michael Vogt <mvo@debian.org> scanlogd Riku Voipio <riku.voipio@iki.fi> setmixer Martin Waitz <tali@debian.org> oidentd Lucas Wall <lwall@debian.org> popfile Hanna Wallach <hmw26@cam.ac.uk> didiwiki Chad Walstrom <chewie@debian.org> clamsmtp Jerome Warnier <jwarnier@beeznest.net> and Joerg Wendland <joergland@debian.org> ipvsadm Brian White <bcwhite@pobox.com> genpower squid-prefetch Martin Wuertele <maxx@debian.org> bopm Matt Zimmerman <mdz@debian.org> umlrun Anton Zinoviev <zinoviev@debian.org> console-cyrillic Marco d'Itri <md@linux.it> binkd lirc Maintainer Team <pkg-lirc-maint@lists.alioth.debian.org> lirc lantz moore <lmoore@debian.org> rplay Sam Hocevar (Debian packages) <sam+deb@zoy.org> gnudip ipfm rinetd }}} |
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CategoryDeveloper | ## This page is linked from sysv-rc postinst script CategoryBootProcess | CategoryDeveloper | CategoryPermalink |
Translation(s): none
Dependency based boot sequence
Before Debian 8.0, Debian used init to boot-up the system. This page provide information of the details to resolve the dependency issues. Since Debian 8.0, Systemd replaced init and the dependency was relied on its target files. The information described here no longer applies to Debian's default in Jessie.
Debian was converted to order the boot sequence using the LSB fields in the header of each init.d script. This has removed several bugs in the former boot sequence, and now makes it easier to keep the sequence correct.
Advantages
Did you ever 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.
Some examples of such problems are 256699 294053, 279297, 311057 and 475626 .
How to add a service when using dependency-based booting
In Debian releases prior to 6.0, a service could be added with update-rc.d:
update-rc.d mydaemon defaults
Starting with Debian 6.0, the insserv command is used instead, if dependency-based booting is enabled:
insserv mydaemon
Where mydaemon is an executable init script placed in /etc/init.d. insserv will produce no output if everything went OK. Examine the error code in $? if you want to be sure.
Both the old and the new way requires an init script to be present in /etc/init.d. For dependency-based booting, the script needs to be an LSB init script.
As of Debian 7 man insserv states
- insserv is a low level tool used by update-rc.d which enables an installed system init script (`boot script') by reading the comment header of the script
so you need not use it instead of update-rc.d - see your local manpage for details.
History of the feature
The feature was proposed at debconf in 2002, and has been worked on since before 2006, and was announced on debian-devel-announce 2008-01-17. A status update message was sent 2008-03-16 and 2008-11-30. The default in Debian was changed to dependency based boot sequencing 2009-07-27, and an updated announcement about the plans for the boot system was sent out 2009-09-05. The default in Debian was changed to run scripts in parallel 2010-05-14 and an announcement was sent on 2010-05-21.
Status
This page was created to keep track of the state of this feature, to make it easier to coordinate an effort to implement it in Debian. It was proposed as a release goal for Lenny. It will be the default boot ordering method for Squeeze. During Debconf in 2009, the default in Sid was changed to use dependency based boot sequencing by default.
A number of bug reports are submitted to request LSB fields in init.d scripts. It is useful to track the ones open in testing as well.
A daily updated archive wide check of init.d scripts is available from http://lintian.debian.org/~pere/ . Piuparts now reports installation errors due to incorrect dependencies, and inconsistencies between update-rc.d calls and LSB fields.
Plan of migration
This is a proposal for a plan to migrate all of Debian over to dependency based boot sequencing.
Change the debconf default in insserv to enable dependency based boot sequencing when the package is installed, if it is safe to do so. Show the question again on upgrades if the conversion isn’t done yet. Remove/disable the option to disable insserv after it is enabled.
Change sysv-rc to depend on insserv, to pull it in on all (non-file-rc) installations.
Wait 6 months, while rewriting policy text to document the new way update-rc.d is going to work.
Drop support for specifying sequence numbers in update-rc.d.
This will enable dependency based boot sequencing for all in Debian from Squeeze and onwards.
How to solve migration problems
package X removed but not purged
If a script in /etc/init.d/ belongs to a package that is removed but not purged, the field is probably missing or is outdated. Purging the package will solve the issue.
package X left obsolete init.d script behind
The script was probably dropped from its package, but the package maintainer forgot to add code in the postinst to remove the obsolete script during upgrades. Removing the script is probably the correct solution. We have seen one report where dpkg would claim that a script was obsolete one time and not obsolete one upgrade later, so this should probably be checked a bit before the script is removed.
To verify that a package really left behind obsolete conffiles, one can run
dpkg-query -W -f='${Conffiles}\n' packagename | grep obsolete
There are several reasons why these scripts are not removed automatically during upgrades. First of all, reporting these issues exposes bugs that should be fixed in the individual packages. Second, it is hard to know if the script reported was left behind for a strange and particular reason, or just forgotten. And last, there is the one report that a non-obsolete script was reported as obsolete. Still not sure if that was for real or not, but until we know the reason, it seemed risky to just remove scripts in other packages during upgrades. Besides doing so from the sysv-rc postinst would be a policy violation.
insserv: warning: script 'X' missing LSB tags and overrides
The /etc/init.d/X script is lacking the LSB fields. Adding them to the script header or as a override file in /etc/insserv/overrides/X would solve it.
insserv: script X: service Y already provided!
Bug in the package with script X: The facility provided in script /etc/init.d/X uses a non-unique value. Changing it to a unique value (for example the script name without .sh ending), solves the issue.
Common problems with init.d script header LSB fields
Here are some problems I have seen with the LSB fields in init.d scripts during the last three years. I provide it here for those of you wondering if your package’s init.d scripts are correct.
- Non-unique Provides field
When two packages have scripts with the same Provides field, it will only be able to install these packages if the init.d script of the other is not present in /etc/init.d/. Packages sharing a common service with other packages could use virtual facilities instead of conflicting provides, or normal dependencies if few packages are involved.
- Incorrect runlevel list
- If the Default-Start and Default-Stop fields do not list the runlevels where a script should be stopped or started, the wrong set of start and stop symlinks will be created when the script is installed, and the boot and shutdown sequence will most likely be incorrect. Fixing it require both updates to the fields, and code in the postinst script to add or remove symlinks that where missing.
Missing dependency on $syslog when logging to syslog
- Without it, services might be started too early during boot and some syslog messages might be lost.
Missing dependency on $remote_fs when needing files in /usr/.
Scripts starting from rcS.d/ will start too early when /usr/ is on NFS, and will probably fail to work because some of its expected files and programs are missing when the script starts.
- Depending on incorrect or non-existing provides
- The intended relationship with another script does not take effect, making the script run too early or too late during boot and shutdown.
To see the boot and reboot sequence dependency 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 list of packages whose init.d script is lacking an LSB header can be fetched from the lintian reports for the init.d-script-missing-lsb-section tag.
To enable dependency based boot, insserv can be used. At debconf7 and FOSDEM 2008 (video), Petter Reinholdtsen gave a talk about the dependency based boot system. To enable it in older versions of Debian, install insserv and activate it like this:
aptitude install insserv && dpkg-reconfigure insserv sysv-rc
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