A couple of rants about Launchpad

[Colin Watson]

On Wed, Mar 11, 2009 at 12:26:42AM +0000, David Gerard wrote:
> 2009/3/10 Colin Watson <cjwatson at ubuntu.com>:
> > Honestly, the only meaning that I can consistently assign to "not
> > supported" is "we'll reject bugs you file about it"; and that isn't the
> > case for 'apt-get dist-upgrade' in general.
> > It is true that such upgrades are less well-tested - that's simply a
> > statement of fact. Nevertheless, they'll generally work and only require
> > relatively minor manual intervention (especially in the hands of
> > knowledgeable users), and we ought not to mislead people into thinking
> > that the tools they like flat-out won't work and that they enter some
> > unsupported twilight zone when they use them, when that isn't true.
> > "Supported" is a more nebulous adjective than I would like!
> 
> Then, to get back to the original phrasing of the questions (rather
> than the word "supported"):
> 
> Can it be expected to work more often than not?

Sometimes it will require manual intervention: for instance you might
have to run 'apt-get dist-upgrade' a few times, or you might have to
explicitly install some package first, or you might have to install a
package with --force-overwrite; that kind of thing. These aren't things
that we feel we can inflict on inexperienced users, but they shouldn't
be major obstacles to anyone who has reasonable familiarity with the
Debian package management toolchain.

As for working with no manual intervention whatsoever, I honestly don't
know. I suspect most upgrades will require some small amount of
intervention, just as do Debian upgrades, but I don't feel this is a
hugely important property for people already happy to operate at the
command line. What you care about is that the services you rely on come
back up at the other end of it; I would not expect this to vary hugely
between 'apt-get dist-upgrade' and update-manager, as essentially the
same packages are involved, but of course problems are possible.

It is possible that our expectation of the level of expertise possessed
by users of 'apt-get dist-upgrade' is incorrect. My *advice* would be
that if you are likely to get upset when manual intervention is required
then you should use a more intelligent upgrade tool whose purpose is to
minimise manual intervention (i.e. update-manager/do-release-upgrade).
My experience is that problems that cannot be fixed at worst by repeated
and reasonably simple invocations of apt-get and/or dpkg are pretty
rare, and I'd consider any such problem to be a high-priority bug.

I am interested in whether you feel that "might require multiple
apt-get/dpkg runs" counts as "works" for this purpose, providing that
the things to do are reasonably obvious to an experienced user and you
get a working system at the end of it. If not, why not?

> *Should* it be expected to work more often than not?

Yes, I think so.

> Who is specifically, actively interested in having it work more often
> than not, in real-world conditions rather than just on a Platonic
> ideal machine using nothing but the CD software?

Every Ubuntu developer is supposed to care about making sure the
packages they maintain conform to policy; the result of doing so will be
that they upgrade correctly.

There is nothing we can do at the apt-get level about third-party
packages that are just plain broken. The whole point of using a simple
package manager like apt-get is that it just does what the packages tell
it to do, and if they tell it to do something insane then it often has
no recourse.

If the problem is actually a bug in apt, then we have a full-time
developer one of whose responsibilities is the maintenance of apt. He
also works on update-manager and testing thereof, and since he has a
very clear understanding of the appropriate divisions between the
different tools I have no doubt that he fixes things in the appropriate
place, which will result in fixes being applied to apt-get dist-upgrades
where it's possible and reasonable to do so.

In the release team, we frequently look at upgrade issues of one kind or
another that involve complex interactions between packages, and we
routinely try to get those fixed in the right places rather than just
slamming workarounds into update-manager.

> I appreciate these may seem pointy questions, but they are the actual
> issue ...

I'm not going to commit to "it will work, and if not you can get Colin
Watson fired". I'm not stupid; Ubuntu has bugs. All I think I can
reasonably do is describe what we generally try to ensure works, and
where the development team is willing to accept bug reports.

(As my recent blog entry should indicate, I take no responsibility for
bug triagers who aren't part of the Ubuntu development team closing bugs
when they shouldn't. When I see this happening I reopen the bugs,
although I cannot realistically read all our bug traffic.)

-- 
Colin Watson                                       [cjwatson at ubuntu.com]