On Fri, Mar 16, 2012 at 03:14:18PM -0500, Jonathan Nieder wrote: > By the way, the above example writes the path to initctl to the > terminal when it is present, which I imagine is not intended. Indeed not. Updated example in the attached patch. > [...] > > Also, the proposal looks underspecified to me: What happens for other > > actions, like stop/restart/reload/force-reload? > Yes, I agree. The example should be corrected to prevent the daemon > from being started by the restart and force-reload actions. This is difficult to include as part of a useful example if we expect the init script to still handle the stop case, because the restart and force-reload actions are so often implemented on top of start+stop. -- Steve Langasek Give me a lever long enough and a Free OS Debian Developer to set it on, and I can move the world. Ubuntu Developer http://www.debian.org/ slangasek@ubuntu.com vorlon@debian.org
From ab57ead712ceaf0c02f68c27f308fb08344fd4a2 Mon Sep 17 00:00:00 2001
From: Steve Langasek <steve.langasek@canonical.com>
Date: Sun, 9 Jan 2011 19:58:58 -0600
Subject: [PATCH] Document generic and upstart-specific init-system
requirements
Add a new section on alternative init systems that outlines the
compatibility requirements for both init replacements and packages shipping
upstart jobs. Closes: #591791
---
policy.sgml | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 68 insertions(+), 0 deletions(-)
diff --git a/policy.sgml b/policy.sgml
index b3c5886..610777d 100644
--- a/policy.sgml
+++ b/policy.sgml
@@ -7188,6 +7188,74 @@ Reloading <var>description</var> configuration...done.
</p>
</sect>
+ <sect id="alternateinit">
+ <heading>Alternate init systems</heading>
+ <p>
+ A number of other init systems are available now in Debian that
+ can be used in place of <package>sysvinit</package>. Alternative
+ init implementations must support running SysV init scripts as
+ described at <ref id="sysvinit"> for compatibility.
+ </p>
+ <p>
+ Packages may integrate with these replacement init systems by
+ providing implementation-specific configuration information about
+ how and when to start a service or in what order to run certain
+ tasks at boot time. However, any package integrating with other
+ init systems must also be backwards-compatible with
+ <package>sysvinit</package> by providing a SysV-style init script
+ with the same name as and equivalent functionality to any
+ init-specific job, as this is the only start-up configuration
+ method guaranteed to be supported by all init implementations. An
+ exception to this rule is scripts or jobs provided by the init
+ implementation itself; such jobs may be required for an
+ implementation-specific equivalent of the <file>/etc/rcS.d/</file>
+ scripts and may not have a one-to-one correspondence with the init
+ scripts.
+ </p>
+ <sect1 id="upstart">
+ <heading>Event-based boot with upstart</heading>
+
+ <p>
+ Packages may integrate with the <prgn>upstart</prgn> event-based
+ boot system by installing job files in the
+ <file>/etc/init</file> directory. SysV init scripts for which
+ an equivalent upstart job is available must query the output of
+ the command <prgn>initctl version</prgn> for the string
+ <tt>upstart</tt> and avoid running in favor of the native
+ upstart job, using a test such as this:
+ <example compact="compact">
+if [ "$1" = start ] && which initctl >/dev/null && initctl version | grep -q upstart
+then
+ exit 1
+fi
+ </example>
+ </p>
+ <p>
+ Because packages shipping upstart jobs may be installed on
+ systems that are not using upstart, maintainer scripts must
+ still use the common <prgn>update-rc.d</prgn> and
+ <prgn>invoke-rc.d</prgn> interfaces for configuring runlevels
+ and for starting and stopping services. These maintainer
+ scripts must not call the upstart <prgn>start</prgn>,
+ <prgn>restart</prgn>, <prgn>reload</prgn>, or <prgn>stop</prgn>
+ interfaces directly. Instead, implementations of
+ <prgn>invoke-rc.d</prgn> must detect when upstart is running and
+ when an upstart job with the same name as an init script is
+ present, and perform the requested action using the upstart job
+ instead of the init script.
+ </p>
+ <p>
+ Dependency-based boot managers for SysV init scripts, such as
+ <prgn>startpar</prgn>, may avoid running a given init script
+ entirely when an equivalent upstart job is present, to avoid
+ unnecessary forking of no-op init scripts. In this case, the
+ boot manager should integrate with upstart to detect when the
+ upstart job in question is started or stopped to know when the
+ dependency has been satisfied.
+ </p>
+ </sect1>
+ </sect>
+
<sect id="cron-jobs">
<heading>Cron jobs</heading>
--
1.7.9.1
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