Differences between revisions 1 and 40 (spanning 39 versions)
Revision 1 as of 2005-08-24 10:55:08
Size: 3261
Editor: anonymous
Comment:
Revision 40 as of 2010-01-01 03:39:01
Size: 10158
Editor: KenyonRalph
Comment: punctuation
Deletions are marked like this. Additions are marked like this.
Line 1: Line 1:
## Auto-converted by kwiki2moinmoin v2005-10-07
Line 3: Line 2:
This is a short documentation about how to make an Init Script LSB-compliant. Most of this page has been pulled from a [http://lists.debian.org/debian-devel/2005/08/msg01172.html message by Petter Reinholdtsen] on [http://lists.debian.org/debian-devel Debian-devel].
Line 5: Line 3:
This page is a quick and dirty draft. It is based on the content in
<URL:http://refspecs.freestandards.org/LSB_2.1.0/LSB-generic/LSB-generic/initscrcomconv.html>.
Is it recommended to read if you want to know more.
A [[LSBInitScripts/DependencyBasedBoot|status page]] for dependency based boot sequencing is
available.
Line 9: Line 6:
Add a block like this in the init.d script (example based on xdebconfigurator):
This is a short documentation about how to make an Init Script LSB-compliant based on the [[http://refspecs.freestandards.org/LSB_3.1.0/LSB-Core-generic/LSB-Core-generic/tocsysinit.html|Chapter 20 of the LSB 3.1]].

LSB-compliant init scripts need to:

 * provide, at least, the following actions: start, stop, restart, force-reload, and status. All of those, except for, status, are required by the [[http://www.debian.org/doc/debian-policy/ch-opersys.html#s9.3.2|Debian Policy, chapter 9.3.2 Writing the scripts]]. "Status" support has been requested into policy, see [[DebianBug:291148|#291148]].

 * return proper exit status codes.
 * document runtime dependencies.
 * [optionally] Log messages using the Init.d functions: log_success_msg, log_failure_msg and log_warning_msg (This would introduce consistent output in scripts, as requested in [[http://lists.debian.org/debian-devel/2005/06/msg00729.html]]
and should also follow
[[http://www.debian.org/doc/debian-policy/ch-opersys.html#s9.4|Debian Policy, chapter 9.4 Console messages from init.d scripts]])

Full information on the actions (and return codes) that LSB scripts have to honor
are available at
[[http://refspecs.freestandards.org/LSB_3.1.0/LSB-Core-generic/LSB-Core-generic/iniscrptact.html|LSB 3.1, Chapter 20.2. Init Script Actions]]. Maintainers should review that section and review / adjust their init.d scripts accordingly.

== Run-time dependencies ==

Adding run-time dependencies was a release goal for Lenny, and dependency based boot sequencing is the default in Squeeze. There is [[LSBInitScripts/DependencyBasedBoot|a separate wiki page]] documenting that effort.

By documenting the run-time dependencies for init.d scripts, it becomes possible to verify the current boot order, order the boot using these dependencies, and also to run boot scripts in parallel to speed up the boot process.

Add a block like this in the init.d script:
Line 11: Line 31:
  ### BEGIN INIT INFO
  # Provides: xdebconfigurator
  # Required-Start: $syslog
  # Required-Stop: $syslog
  # Should-Start: $local_fs
  # Should-Stop: $local_fs
  # Default-Start: 2 3 4 5
  # Default-Stop: 0 1 6
  # Short-Description: Generate xfree86 configuration at boot time
  # Description: Preseed X configuration and use dexconf to
  # generate a new configuration file.
  ### END INIT INFO
### BEGIN INIT INFO
# Provides: scriptname
# Required-Start: $remote_fs $syslog
# Required-Stop: $remote_fs $syslog
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: Start daemon at boot time
# Description: Enable service provided by daemon.
### END INIT INFO
Line 25: Line 42:
All sections except the description-sections are space separate lists. The block shown above has a special rigid format delimited by the lines
Line 27: Line 44:
Provides should list the name of this service, normally the script name but might also list the name of services it "replaces". {{{
### BEGIN INIT INFO
### END INIT INFO
}}}
Line 29: Line 49:
Required-Start are services needed to start this service. These services must start before this service. Required-Stop are services used by this service, and this service should stop before the listed services are stopped. where all trailing spaces shall be ignored. On the other hand, all lines inside the block shall be of the form
{{{
# {keyword}: arg1 [arg2...]
}}}
Line 31: Line 54:
Should-Start are services that if present should start before this service, but this service can start if the listed services are missing. Should-Stop are services that if present should be stopped after this service. and begin with a hash character '#' in the first column followed by one single space, except for the lines following the Description keyword. The following keywords are defined
Line 33: Line 56:
Default-Start is the run levels where this service should be started by default, and Default-Stop is the run levels where this service should be stopped by default.
Line 35: Line 57:
Description and short-description are fairly obvious. '''Provides: boot_facility_1 [boot_facility_2...]'''
Line 37: Line 59:
For dependency tracking, the required-''' and should-''' are important, and the rest is unused. The default runlevels are used by insserv to keep track of which rc#.d directory to update when a service is added for the first time, and should reflect the intent of the service.     defines boot facilities provided by this init script such that when the script is run with the start argument, the
    specified boot facilities will be deemed present and hence other init scripts which require those boot facilities
    will be started at a later stage. Normally you should use the script name as boot facility (without .sh if the file name have such ending) but one can in the exceptional case also use the name of the
    service(s) that the script replaces. Virtual facility names should not be listed here. Those are defined outside the init.d scripts. The provides name should be unique within the distribution, to avoid duplicate provides errors when a package is installed.
Line 39: Line 64:
There are some "virtual"''system service names, listed in <URL:http:''/refspecs.freestandards.org/LSB_2.1.0/LSB-generic/LSB-generic/facilname.html>.
'''Required-Start: boot_facility_1 [boot_facility_2...]'''

    defines facilities that must be available to start the script. Consider using virtual facility names as described
    below if adequate. If no boot facility is specified it means that this script can be started just after the bootstrap
    without local filesystems mounted, nor system logger, etc.

'''Required-Stop: boot_facility_1 [boot_facility_2...]'''

   defines facilities used by the service provided by the script. The facility provided by this script should stop before the listed facilities are stopped to avoid conflicts. Normally you would include here the same facilities as for the Required-Start keyword.


'''Should-Start: boot_facility_1 [boot_facility_2...]'''

    defines the facilities that if present should start before the service provided by the script. Nevertheless, the script can still start if the listed facilities are missing. This allows for weak dependencies which do not cause the service to fail if a facility is not available. Consider using virtual facility names as described below if adequate.

'''Should-Stop: boot_facility_1 [boot_facility_2...]'''

    defines the facilities that if present should be stopped after this service. Normally you would include here the same facilities as those used with the Should-Start keyword.


'''Default-Start: run_level_1 [run_level_2...],Default-Stop: run_level_1 [run_level_2...]'''

    defines the run levels where the script should be started (stopped) by default. For example, if a service should run in runlevels 3, 4, and 5 only, specify "Default-Start: 3 4 5" and "Default-Stop: 0 1 2 6".

'''Short-Description: short_description'''

    provide a brief description of the actions of the init script. Limited to a single line of text.

'''Description: multiline_description'''

    provide a more complete description of the actions of the init script. May span multiple lines. In a multiline description, each continuation line shall begin with a '#' followed by tab character or a '#' followed by at least two space characters. The multiline description is terminated by the first line that does not match this criteria.

'''X-Start-Before: boot_facility_1 [boot_facility_2...]'''

'''X-Stop-After: boot_facility_1 [boot_facility_2...]'''

    provide reverse dependencies, that appear as if the listed facilities had should-start and should-stop on the package with these headers.

For dependency tracking, the provides, required- and should- keywords are important, and the rest is unused. The default runlevels are used by a program to order the init scripts (e.g. insserv) to keep track of which rc#.d directory to update when a service is added for the first time, and should reflect the intent of the service.

There are some "virtual" facility names, listed in the
[[http://refspecs.freestandards.org/LSB_3.1.0/LSB-Core-generic/LSB-Core-generic/facilname.html|[LSB 3.1]]].
Line 42: Line 109:
|| $local_fs || all local filesystems are mounted || || $local_fs || all local filesystems are mounted. All scripts that write in /var/ need to depend on this, unless they already depend on $remote_fs. ||
Line 45: Line 112:
|| $portmap || daemons providing ["SunRPC"]/ONCRPC portmapping service as defined in RFC 1833 (if present) are running all remote ||
|| $remote_fs || filesystems are mounted. In some LSB run-time environments, filesystems such as /usr may be remote. Many applications that require $local_fs will probably require also require $remote_fs. ||
|| $portmap || daemons providing [[SunRPC]]/ONCRPC portmapping service as defined in RFC 1833 (if present) are running all remote ||
|| $remote_fs || all filesystems are mounted. In some LSB run-time environments, filesystems such as /usr may be remote. If the script need a mounted /usr/, it need to depend on $remote_fs. Scripts depending on $remote_fs do not need to depend on $local_fs. During shutdown, scripts that need to run before sendsigs kills all processes should depend on $remote_fs. ||
Line 49: Line 116:
|| $all || facility supported by insserv to start a script after all the other scripts, at the end of the boot sequence. This only work for start ordering, not stop ordering. It is not possible to depend on a script which depend on $all. ||

Other (non-system) facilities may be defined by other applications. These facilities shall be named using the same [[http://refspecs.freestandards.org/LSB_3.1.0/LSB-Core-generic/LSB-Core-generic/etc.html#FHS-NAME-RULES|conventions defined for naming init scripts]]. See [[LSBInitScripts/DebianVirtualFacilities|the list of proposed Debian specific virtual facilities]] for more information on this.


Most of this section was originally based from a [[http://lists.debian.org/debian-devel/2005/08/msg01172.html|message by Petter Reinholdtsen]] on [[http://lists.debian.org/debian-devel|Debian-devel]].

BTS reports related to LSB headers are [[http://bugs.debian.org/cgi-bin/pkgreport.cgi?usertag=initscripts-ng-devel@lists.alioth.debian.org|usertagged]].

-----

== Frequent questions ==

 Is it possible to start a given init script as late as possible? :: yes, if you really want to do so, insserv recognises the $all virtual facility name such that the script will be executed at the end.

 Is it possible to add extra keywords? :: If there is no current keyword you could use for your needs, the LSB allows for local extensions using the prefix X-. For example, X-Debian-foobardecl or X-Ubuntu-fastdecl.

 Is it possible to specify that a given script should start before another script? :: There is no such standard-defined header, but there is a proposed extention implemented in the insserv package (since version 1.09.0-8). Use the X-Start-Before and X-Stop-After headers propsed by SuSe.

 Shouldn't I wait until the Debian policy changes? :: The Debian policy changes are slow to introduce even for things (for an example, see [[DebianBug:291148|#291148]]) which most maintainers agree are good since we have to wait first for many packages to do things in the same way before turning it into policy. Since we want to be LSB compliant, init.d scripts can be adjusted '''now''' to be LSB compliant.

 What is a "proper" exit status code? :: Looking at [[DebianBug:208010|#208010,]] this seems rather controversial. Non-zero exit codes might even cause breakage, and the LSB conflicts with Debian policy here.

How to LSBize an Init Script

A status page for dependency based boot sequencing is available.

This is a short documentation about how to make an Init Script LSB-compliant based on the Chapter 20 of the LSB 3.1.

LSB-compliant init scripts need to:

and should also follow Debian Policy, chapter 9.4 Console messages from init.d scripts)

Full information on the actions (and return codes) that LSB scripts have to honor are available at LSB 3.1, Chapter 20.2. Init Script Actions. Maintainers should review that section and review / adjust their init.d scripts accordingly.

Run-time dependencies

Adding run-time dependencies was a release goal for Lenny, and dependency based boot sequencing is the default in Squeeze. There is a separate wiki page documenting that effort.

By documenting the run-time dependencies for init.d scripts, it becomes possible to verify the current boot order, order the boot using these dependencies, and also to run boot scripts in parallel to speed up the boot process.

Add a block like this in the init.d script:

### BEGIN INIT INFO
# Provides:          scriptname
# Required-Start:    $remote_fs $syslog
# Required-Stop:     $remote_fs $syslog
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: Start daemon at boot time
# Description:       Enable service provided by daemon.
### END INIT INFO

The block shown above has a special rigid format delimited by the lines

### BEGIN INIT INFO
### END INIT INFO

where all trailing spaces shall be ignored. On the other hand, all lines inside the block shall be of the form

# {keyword}: arg1 [arg2...]

and begin with a hash character '#' in the first column followed by one single space, except for the lines following the Description keyword. The following keywords are defined

Provides: boot_facility_1 [boot_facility_2...]

  • defines boot facilities provided by this init script such that when the script is run with the start argument, the specified boot facilities will be deemed present and hence other init scripts which require those boot facilities will be started at a later stage. Normally you should use the script name as boot facility (without .sh if the file name have such ending) but one can in the exceptional case also use the name of the service(s) that the script replaces. Virtual facility names should not be listed here. Those are defined outside the init.d scripts. The provides name should be unique within the distribution, to avoid duplicate provides errors when a package is installed.

Required-Start: boot_facility_1 [boot_facility_2...]

  • defines facilities that must be available to start the script. Consider using virtual facility names as described below if adequate. If no boot facility is specified it means that this script can be started just after the bootstrap without local filesystems mounted, nor system logger, etc.

Required-Stop: boot_facility_1 [boot_facility_2...]

  • defines facilities used by the service provided by the script. The facility provided by this script should stop before the listed facilities are stopped to avoid conflicts. Normally you would include here the same facilities as for the Required-Start keyword.

Should-Start: boot_facility_1 [boot_facility_2...]

  • defines the facilities that if present should start before the service provided by the script. Nevertheless, the script can still start if the listed facilities are missing. This allows for weak dependencies which do not cause the service to fail if a facility is not available. Consider using virtual facility names as described below if adequate.

Should-Stop: boot_facility_1 [boot_facility_2...]

  • defines the facilities that if present should be stopped after this service. Normally you would include here the same facilities as those used with the Should-Start keyword.

Default-Start: run_level_1 [run_level_2...],Default-Stop: run_level_1 [run_level_2...]

  • defines the run levels where the script should be started (stopped) by default. For example, if a service should run in runlevels 3, 4, and 5 only, specify "Default-Start: 3 4 5" and "Default-Stop: 0 1 2 6".

Short-Description: short_description

  • provide a brief description of the actions of the init script. Limited to a single line of text.

Description: multiline_description

  • provide a more complete description of the actions of the init script. May span multiple lines. In a multiline description, each continuation line shall begin with a '#' followed by tab character or a '#' followed by at least two space characters. The multiline description is terminated by the first line that does not match this criteria.

X-Start-Before: boot_facility_1 [boot_facility_2...]

X-Stop-After: boot_facility_1 [boot_facility_2...]

  • provide reverse dependencies, that appear as if the listed facilities had should-start and should-stop on the package with these headers.

For dependency tracking, the provides, required- and should- keywords are important, and the rest is unused. The default runlevels are used by a program to order the init scripts (e.g. insserv) to keep track of which rc#.d directory to update when a service is added for the first time, and should reflect the intent of the service.

There are some "virtual" facility names, listed in the [LSB 3.1]. These are:

$local_fs

all local filesystems are mounted. All scripts that write in /var/ need to depend on this, unless they already depend on $remote_fs.

$network

low level networking (ethernet card; may imply PCMCIA running)

$named

daemons which may provide hostname resolution (if present) are running. For example, daemons to query DNS, NIS+, or LDAP.

$portmap

daemons providing ?SunRPC/ONCRPC portmapping service as defined in RFC 1833 (if present) are running all remote

$remote_fs

all filesystems are mounted. In some LSB run-time environments, filesystems such as /usr may be remote. If the script need a mounted /usr/, it need to depend on $remote_fs. Scripts depending on $remote_fs do not need to depend on $local_fs. During shutdown, scripts that need to run before sendsigs kills all processes should depend on $remote_fs.

$syslog

system logger is operational

$time

the system time has been set, for example by using a network-based time program such as ntp or rdate, or via the hardware Real Time Clock.

$all

facility supported by insserv to start a script after all the other scripts, at the end of the boot sequence. This only work for start ordering, not stop ordering. It is not possible to depend on a script which depend on $all.

Other (non-system) facilities may be defined by other applications. These facilities shall be named using the same conventions defined for naming init scripts. See the list of proposed Debian specific virtual facilities for more information on this.

Most of this section was originally based from a message by Petter Reinholdtsen on Debian-devel.

BTS reports related to LSB headers are usertagged.


Frequent questions

Is it possible to start a given init script as late as possible?
yes, if you really want to do so, insserv recognises the $all virtual facility name such that the script will be executed at the end.
Is it possible to add extra keywords?
If there is no current keyword you could use for your needs, the LSB allows for local extensions using the prefix X-. For example, X-Debian-foobardecl or X-Ubuntu-fastdecl.
Is it possible to specify that a given script should start before another script?

There is no such standard-defined header, but there is a proposed extention implemented in the insserv package (since version 1.09.0-8). Use the X-Start-Before and X-Stop-After headers propsed by ?SuSe.

Shouldn't I wait until the Debian policy changes?

The Debian policy changes are slow to introduce even for things (for an example, see #291148) which most maintainers agree are good since we have to wait first for many packages to do things in the same way before turning it into policy. Since we want to be LSB compliant, init.d scripts can be adjusted now to be LSB compliant.

What is a "proper" exit status code?

Looking at #208010, this seems rather controversial. Non-zero exit codes might even cause breakage, and the LSB conflicts with Debian policy here.