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Re: postrm::downgrade?

> > On Wed, Jul 02, 2003 at 03:18:36PM +0800, Niall Young wrote:
> >
> > I'm using a custom package pool for deploying software, but we need to
> > cleanly rollback if an upgrade doesn't go as expected.
> In easy cases it is possible to first test a package with some testing
> machine and only put in in the used archive when it suites your needs.

Agreed, I meant in *addition* to pre-deployment testing - say if testing
didn't pick up all bugs and you discover fatal problems post deployment.

> > How about a postrm::downgrade hook to reverse any changes made in the
> > new version's preinst::upgrade so that when the old version's
> > preinst::upgrade
> > is applied you're not left with a potential mix of configuration?
> > seamlessly - i.e. reverse all changes made in the upgrade.  Is there
> > another way?
> You'd need more than that. Apt would need to be changed to handle
> undoing of package splitting (Conflicts/Replaces), and is not always
> possible anyway, new packages, might use new file-formats which can be
> converted from the old-version but not back again.

Yeah - it's a minefield of nightmares I know.  Debian handles upgrades
really well, but downgrades aren't as seamless.  A postrm::downgrade
hook is a pretty major change, it would take years to roll out - just
wondering if anyone has thought about the problem before and if/when
Debian could address this?  A remove and clean install seems to be the only
option which is unfortunate.  Something to think about at least...

Niall Young                                    Chime Communications Pty Ltd
niall@chime.net.au                            Level 6, 263 Adelaide Terrace
Ph: (+61) 08 9213 1330 / 0408 192 797         Perth, Western Australia 6000

    "donate to our Charity of the month which is the Eating Disorders
    Association of WA Inc. ...  give a gold coin donation and I'll reward
    you with nice sweettttt chocolate! MMMMM"
                                        -- Jodie Evans, Feb 2003

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