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Re: policy changes toward Non-Interactive installation



On Mon, Aug 14, 2000 at 11:38:28PM -0700, Joey Hess wrote:
> > ======================================================================
> >  ------------- Question depends on test on fie system
> > / ------------ Question important (IMHO)
> > |/ ----------- Depends on previous answer         
> > ||/ ---------- Needs run time test
> > |||/         __ can be pre asked
> > ||||        /
> > ||||        |
> > ||||        |   
> > X...........Y    1) Ask to remove /System.map files
> > .X          Y    2) ask to prepare a boot floppy
> > XXX.........Y    3) ask which floppy drive to use
> > .XX.........?    4) do I need to format the floppy?
> > .XXX........N    5) Insert floppy, hit return
> > .XXX........N    6) failure, retry?
> > .XXX........N    7) failure, you have formatted floppy?
> > .XXX........N    8) you have floppy, hit return when ready
> > .XXX........N    9) Failure writing floppy, retry?
> > .XXX........N   10) failure, hit return when youhave new floppy
> > XX..........Y   11) if conf exists ask if we should run $loader with old config
> > XXX.........Y   12)                Or else ask if a new $loader config
> > .XX.........Y   13) Or else ask if loader needed at all
> > .XX.........N   14) Install boot vlock on partition detected at runtime
> > XXXX........N   15) Install mbr root disk
> > .XXX........N   16) Failure writing mbr, do this manually, hit return 
> > .XX.........N   17) make that partition active?
> > ======================================================================
> 
> Right. This is obviously a rather important package, which *cannot*
> fail, plus is is very dependant on the actual state of the system. As
> such, the best you'll be able to do is allow a few questions to be
> pre-asked, and defer the remainder to the appropriate maintainer script.
> 
> (BTW, I'm ccing this to Wichert and AJ as a sterling example of why
> debconf has to continue to support this type of thing in maintainer
> scripts. I think both of them don't want it to have this capability,[..]

You'd be at least half right.

To clarify a little: I want to be able to answer the questions up front,
do the install and have it work. If I've made a mistake (like not put a
file where I said I did maybe), I don't mind if it dies and leaves that
package to be configured later or something. I don't want it to pause
and leave the rest of the system unconfigured, though.

This is just for my system, I don't really care that much how it works
for other people.

If we go through the `N' questions above, we have:

> > .XXX........N    6) failure, retry?
> > .XXX........N    7) failure, you have formatted floppy?
> > .XXX........N    9) Failure writing floppy, retry?
> > .XXX........N   10) failure, hit return when youhave new floppy
> > .XXX........N   16) Failure writing mbr, do this manually, hit return 

...failure cases, which I want to address as late as possible, rather
than as soon as possible. (The realplayer question is mainly a failure
question too, iirc)

> > .XXX........N    5) Insert floppy, hit return
> > .XX.........?    4) do I need to format the floppy?
> > .XXX........N    8) you have floppy, hit return when ready

...questions needing a temporary change in hardware. I'd answer "no,
I don't want to have a floppy" initially, or perhaps want to run
/usr/lib/kernel-2.2.17/make-floppy or something after my install's
completed.

> > .XX.........N   14) Install boot block on partition detected at runtime

You can detect stuff at runtime from within the .config too; you should
be able to this before the package is actually installed. At worst, you
can say "no, don't try to detect it and annoy me later: this is what it
should be. okay? trust me"

> > XXXX........N   15) Install mbr root disk
> > .XX.........N   17) make that partition active?

And hence you should be able to ask these beforehand too, I think.

Basically, I'd like to be able to insist that I'm *never* asked a question
as part of a postinst. I'd rather the postinst fail (and I'd rather Apt/Dpkg
just get on with installing everything else, although it probably won't at
the moment) than get asked a question.

One way of dealing with this might be to have a debconf question,
debconf/interactive-postinst. If this is answered "no", then attempts to
ask questions from the postinst (rather than the config) should simply
fail with an error return. In .config's, logic somewhat like:

	db_input kernel-image-blah/make-a-boot-floppy
	if kernel-image-blah/make-a-boot-floppy = yes; then 
		if debconf/interactive-postinst = no; then
			db_input kernel-image-blah/cant-make-a-boot-floppy
			db_set kernel-image-blah/make-a-boot-floppy no
		fi
	fi

should be used, I suppose. Or perhaps:

	if debconf/interactive-postinst = yes; then
		db_input kernel-image-blah/make-a-boot-floppy
	else
		db_input kernel-image-blah/cant-make-a-boot-floppy
		db_set kernel-image-blah/make-a-boot-floppy no
	fi

would be tidier. For the moment, though, as long as I *can* say "no,
I don't want a floppy made" and end up with a non-interactive postinst,
I'm happy.

Cheers,
aj

-- 
Anthony Towns <aj@humbug.org.au> <http://azure.humbug.org.au/~aj/>
I don't speak for anyone save myself. GPG signed mail preferred.

  ``We reject: kings, presidents, and voting.
                 We believe in: rough consensus and working code.''
                                      -- Dave Clark

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