[Pkg-sysvinit-devel] Future of update-rc.d in wheezy+1

[Roger Leigh]

On Mon, Jul 02, 2012 at 12:16:31AM +0100, Roger Leigh wrote:
> On Fri, Jun 29, 2012 at 10:53:03PM +0100, Roger Leigh wrote:
> > On Fri, Jun 29, 2012 at 08:27:22PM +0100, Roger Leigh wrote:
> > > The following patch implements this behaviour.  While the insserv
> > > parsing logic has been tested, it's not been tested for upgrades
> > > or whether the whole script works correctly.
> > > 
> > > - it needs a Depends on insserv (>= $version_with_-s)
> > >   ==> this needs your feedback so it can be uploaded.
> > > - the preinst could be simplified to just use
> > >     update-rc.d "$script" -f defaults
> > >   if this is sufficient to update the sequence numbers in the
> > >   configuration.  This probably needs running in the postinst TBH.
> > > - this just replaces the defaults and user-provided start and stop
> > >   arguments with those provided by insserv.  Other than that, there
> > >   are no changes to anything else.
> > > - You might need to retain support for the old-style logic so that
> > >   if other scripts call update-rc.d in the gap between unpacking and
> > >   running the postinst, it won't fail.  Just back out the deletions
> > >   and run those blocks only if insserv didn't run or didn't find any
> > >   matches, which are a trivial addition to the script.
> > > 
> > > While this patch is just a proof a concept, this should be pretty much
> > > all you need.  It just needs checking and testing by someone with
> > > file-rc expertise.  If this could be done in the very near future,
> > > then that would be great.
> > 
> > I've attached an updated patch.
> 
> Another patch attached.  This one is somewhat more comprehensive.
> 
> - insserv support is "optional".  If insserv is not present, it will
>   fall back to using static sequence numbers.  This will provide
>   backward compatibility for squeeze upgrades.  For new installations
>   from wheezy however, it will generate runlevel.conf using insserv.
>   For wheezy+1, you'll likely be required to migrate existing users
>   to using insserv, but for now it's optional.
> - the output functions have been refactored to include start and
>   stop entries on separate lines, because this is the common case
>   (due to the sequence numbers for start and stop making no sense to
>   be the same, unless it's pure coincidence).
> - long obsolete code removed from maintainer scripts.
> 
> I've documented most of the user-visible change in NEWS.Debian and
> the changelog.
> 
> The most important change is this: runlevel.conf is no longer user-
> editable, except for adding and removing lines.  When using insserv,
> the sequence numbers mean nothing, because they are dynamically
> generated from the dependency information.  When you run update-rc.d,
> the numbers could potentially change if a script is added or removed
> from the middle of the sequence, causing all following scripts to be
> renumbered.  This means that only two operations are possible:
> 1. remove a script.  This is equivalent to "update-rc.d remove"
> 2. add a script.  This is equivalent to
>    "update-rc.d defaults|start|stop" (which are all equivalent from
>    the insserv POV--they all just add/update the entries for the
>    script according to the LSB dependencies)
> So if you want to reorder the scripts, you just edit the LSB header
> in the init script, and then run "update-rc.d foo defaults" to
> effect the change.  This is a change from the historical behaviour
> of file-rc, but it's the logical consequence of having dependency-
> based boot: you edit the dependencies, not the script numbers.
> 
> Hope this all looks reasonable.  I've tested all the insserv
> codepaths, but not the non-insserv case yet.  Testing
> file-rc -> sysv-rc migration also needs doing (the change to
> not restore the rcS links probably needs reverting).  Anyway,
> I hope this is useful as a basis for implementing insserv
> support in file-rc; hopefully I've done the bulk of the work and
> it just remains to test and tweak, or back out any changes you're
> unhappy with.  I'd appreciate any feedback; I can make any further
> changes you need if you let me know what you want.

Hi Alexander,

I've attached a (hopefully final) patch.  We now have updated
insserv and sysvinit packages in unstable, so it's now safe to
enable this.  It will work with or without insserv, so will
work fine for upgrades and new installs.  It now transparantly
works to install file-rc and sysv-rc and the configuration is
migrated both ways depending on which you install.


Regards,
Roger

-- 
  .''`.  Roger Leigh
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