Re: Downgrading packages after removing a repository
On 2009-08-04 13:14:25 -0500, C de-Avillez wrote: > On Tue, 2009-08-04 at 17:56 +0200, Michael Bienia wrote: > > On 2009-08-01 19:49:33 +0100, Andrew Sayers wrote: > > > When you add a repository to your computer, then remove that repository, > > > it's not obvious how to downgrade packages that are no longer available.. > > > > Downgrades are not supported, while in practise they work in most cases. > > Offering such a downgrade option will probably lead to bugs about broken > > downgrades as people will assume that it should work. > > > > Downgrade will certainly fail if the format of user data has changed > > (e.g. a new database format or config file format). Assuming that the > > new version will upgrade the data to new format on the first run, the > > data won't be usable after a downgrade anymore (the old version doesn't > > understand the new format). > > Indeed. Some options seem to apply, though: offer to replace the current > configuration with the maintainers one; warn the user the the current > user data format is incompatible with the one provided in this version, > and that the user will have to *manually* recover; etc, etc. > > Still, this is not a reason *not* to provide such service. We already > provide a similar service in the other direction. Also, I am not aware > of API/ABI changes *within* a version (or Ubuntu release) being a common > case. So, for most cases, we are talking only about updates/downgrades > *within* a version/release. If you limit this to use-cases with requirements (like only updates from -security or -updates) when it should be possible to downgrade, then it's easier to do than a "generic downgrade" like it sounded in the first mail. > Nevertheless, I agree that downgrading to a *previous* version is a > potentially dangerous situation, and should not be offered to either the > casual or experienced user. > > > > > While not the best solution, make downgrades only available to those > > who know that downgrades might fail and that they're left alone in such > > a case, will hopefully prevent that people assume that downgrades will > > always succeed. > > Although this is the current practice everywhere (not only on Ubuntu), > and I am not aware of any implementation of this idea, the proposal > still *can* bring value to the table. I certain would love it. And I > think that this would bring even more value for Ubuntu. Surely, making downgrades more easily sounds fine. But like any other feature it needs developers time and also testing that it works and not breaks even more horrible. And as developer time is a rare resource one needs to use it wisely. And using it on a feature which will be only used by a few people while there are enough bug reports in Launchpad about other bugs (incl. upgrade problems) doesn't sound wise to me. > User Case. Jacob upgraded to a -updates package. This upgrade seems to > have broken something (perhaps a regression), and he wants to get back. This is a very specific use-case where downgrades might be possible. The involved packages and versions are pretty well known and the changes to a package between release and release-updates are rather small. Doing the same for -backports which might include complete new upstream versions is on the other hand not so easy anymore. > If what you state were to be generically valid, then Ubuntu must keep > the parts. For -updates Ubuntu tries its best to avoid regressions and in case a severe regression slips through stops the specific update. Michael -- Ubuntu-devel-discuss mailing list Ubuntu-devel-discuss@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss
Re: Downgrading packages after removing a repository
On 2009-08-04 18:28:17 +0100, Andrew Sayers wrote: > You make a good point about breakage when packages are downgraded. But > it seems a little disingenuous for us to bend over backwards to make > unsupported upgrades possible (adding a "software sources" menu item, > putting PPAs in Launchpad, creating /etc/apt/sources.list.d/ and so on), > then for us to walk away when those upgrades make systems unusable. There are certainly use-cases where this is usefull and people using it know what they are doing. Disable such options won't make the problems go away. Removing the option to add software sources through a GUI will only lead to instructions how to add them by adding/editing files in /etc/apt/. If you remove that too, you will find instructions to download the deb and "dpkg -i" it instead. In all cases users will follow them without thinking because the instructions promised them a new version or programm with more bling as they currently have. Indepenent of how hard you make it to break an installation, there will be someone who managed to break it nonetheless and expects from you to unbreak it. And at the same time you will annoy experienced users who know what they are doing. > I also take your point that pain is an important way of communicating > danger to users. But making a system unusable seems like pushing a man > off a cliff to warn him about the dangers of falling. I see it more like using an old, rotten bridge with a big warning "Use at your own risk." You might be lucky and can use it to get to the other side and back again without problems, your might get to the other side and the bridge breaks after you or if you're unlucky, you might not even reach the other side. But your shouldn't complain afterwards if you hurt yourself trying to reach the other side. I'm pretty sure people will be carefull when they should use these (even without a big warning): http://www.scottishmunros.co.uk/assets/galleries/photos/_resampled/Resize500500-7018-Rotten-Bridge-to-Maol-Chean-Dearg-2.jpg http://outdoors.webshots.com/photo/1113598721040505749FqtOqH In this regard people seem to apply some common sense and not use this bridge if it looks unsafe to them but if it comes to software they believe you everything you tell them. Michael -- Ubuntu-devel-discuss mailing list Ubuntu-devel-discuss@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss
Re: Downgrading packages after removing a repository
Michael Bienia wrote: > Indepenent of how hard you make it to break an installation, there will > be someone who managed to break it nonetheless and expects from you to > unbreak it. And at the same time you will annoy experienced users who > know what they are doing. I don't follow this part. Could you explain how the proposed solution (warnings on upgrade, warnings on downgrade) increases the number of people who expect Ubuntu to unbreak their system, or the number of annoyed experienced users? - Andrew -- Ubuntu-devel-discuss mailing list Ubuntu-devel-discuss@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss
Re: Downgrading packages after removing a repository
Michael Bienia wrote: > On 2009-08-05 12:55:04 +0100, Andrew Sayers wrote: >> Michael Bienia wrote: >> >>> Indepenent of how hard you make it to break an installation, there will >>> be someone who managed to break it nonetheless and expects from you to >>> unbreak it. And at the same time you will annoy experienced users who >>> know what they are doing. >> I don't follow this part. Could you explain how the proposed solution >> (warnings on upgrade, warnings on downgrade) increases the number of >> people who expect Ubuntu to unbreak their system, or the number of >> annoyed experienced users? > > It was related to the part where you commented that if Ubuntu makes it > possible to break installations (addind 3rd party repositories) it > should also provide tools to unbreak it again. > But perhaps I misunderstood it or read too much into it that if Ubuntu > doesn't provide these tools, it shouldn't provide options to shoot > oneself into the foot (possibly break an installation). > > Adding additional warnings might help if done right, but I currently see > some problems I don't currently see a solution for: > - you certainly won't warn on every upgrade else the warning is useless > (when you warn about every possible upgrade the warning gets ignored: >the last 20 upgrades went fine, why should this one break things?) > - how to identify repositories to warn about updates from? > - you can't rely on apt (or dpkg) about the warning (how should it know > which updates are "safe" and which not) and you can't rely on the > packages itself either (which 3rd party package will contain a warning > that it might break user data on downgrades?) > > Michael > These are very good points - how about warning when upgrading to a version with a different Origin, Label, Suite, Version, or Codename line in the Release file, or when enabling downgrades? For example: These packages will be upgraded from repositories that are incompatible with their current repositories: * libfoo * old origin: Ubuntu * new origin: LP-PPA-andrew-bugs-launchpad-net * gbar * old origin: LP-PPA-andrew-bugs-launchpad-net * new origin: Evilsoft Inc. * old label: Ubuntu * new label: EvilWare * kqux * old suite: jaunty * new suite: karmic * old codename: jaunty * new codename: karmic * old version: 9.04 * new version: 9.10 WARNING: Incompatible repositories are not supported. Incompatible repositories can cause data loss, can make programs unable to run, and can even make your computer unable to boot. And: WARNING: downgrades are not supported. Downgrading packages can cause data loss, can make programs unable to run, and can even make your computer unable to boot. On the command-line, I would suggest printing the upgrade warning whenever relevant packages are apt-get installed or upgraded, and putting the downgrade warning next to the relevant command-line option in the man page. In a GUI, I would suggest printing the upgrade warning whenever packages are installed or upgraded in any way, and printing the downgrade warning when the user clicks on some type of "allow downgrades for this session" button. - Andrew -- Ubuntu-devel-discuss mailing list Ubuntu-devel-discuss@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss
Re: Downgrading packages after removing a repository
2009/8/1 Andrew Sayers : > When you add a repository to your computer, then remove that repository, > it's not obvious how to downgrade packages that are no longer available. > https://edge.launchpad.net/~xorg-edgers/+archive/ppa/+files/ppa-purge_0.2.2~jaunty.dsc Removes a ppa and downgrades that was pulled from it. AWESOME =) -- With best regards Dmitrijs Ledkovs (for short Dima), Ледков Дмитрий Юрьевич -- Ubuntu-devel-discuss mailing list Ubuntu-devel-discuss@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss
Re: Downgrading packages after removing a repository
On Thu, 2009-08-06 at 01:08 +0300, Dmitrijs Ledkovs wrote: > 2009/8/1 Andrew Sayers : > > When you add a repository to your computer, then remove that repository, > > it's not obvious how to downgrade packages that are no longer available. > > > > https://edge.launchpad.net/~xorg-edgers/+archive/ppa/+files/ppa-purge_0.2.2~jaunty.dsc > > Removes a ppa and downgrades that was pulled from it. > > AWESOME =) Indeed Dima! Seb had also pointed me to it today. But, still, Michael's observations still apply: we must be careful on downgrading, pretty much like we are careful when upgrading, possibly even more: differences on configuration files, or how data is handled, may cause serious problems. It *is* possible, and the ppa-purge script shows it. But... much more care will have to be taken to get from this point to something that can be provided to not-so-experienced-users-if-at-all. But I was really happy to see that we (up to now, Andrew, Michael, myself, and you; well, and Sebastien) were not the only ones thinking about it (even if Seb, like Michael, is unsure). Hell, *I* am unsure! But it would really be nice. In my case, I am usually on the road, so I only have my personal laptop as a testbed. Being able to test/try something, and revert back with minimal effort, is a really good gain. signature.asc Description: This is a digitally signed message part -- Ubuntu-devel-discuss mailing list Ubuntu-devel-discuss@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss
Re: Ubuntu-devel-discuss Digest, Vol 33, Issue 2
Tony Weitekamp 361-737-2569 Windows .- .- .- .- .Where do you want to go today? MacOSX .- .- .- .- .-Where do you want to be tomorrow? Linux .- .- .- .- .- Are you coming or what? ubuntu-devel-discuss-requ...@lists.ubuntu.com wrote: > Send Ubuntu-devel-discuss mailing list submissions to > ubuntu-devel-discuss@lists.ubuntu.com > > To subscribe or unsubscribe via the World Wide Web, visit > https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss > or, via email, send a message with subject or body 'help' to > ubuntu-devel-discuss-requ...@lists.ubuntu.com > > You can reach the person managing the list at > ubuntu-devel-discuss-ow...@lists.ubuntu.com > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Ubuntu-devel-discuss digest..." > > > Today's Topics: > >1. Re: Two packages form Ubuntu 8.04 (amd64) (Siegfried-Angel) >2. Re: Downgrading packages after removing a repository > (C de-Avillez) >3. Re: Downgrading packages after removing a repository > (Michael Bienia) >4. Re: Downgrading packages after removing a repository > (Andrew Sayers) >5. Re: Downgrading packages after removing a repository > (C de-Avillez) >6. Re: Downgrading packages after removing a repository > (Michael Bienia) >7. Re: Downgrading packages after removing a repository > (Michael Bienia) > > > This discussion looks very similar to the Hundred Paper Cuts Discussion from a few weeks ago. The addition of one software package can virtually break your Ubuntu install. The solution that was proposed to me was to have many machines, each running a specific configuration. This is unsatisfactory for people who are resource limited, and in possession of only one (1) Linux machine. Is there a way to save package configurations in a database or flat file so upgraded packages/repositories can be rolled back? Tony > -- > > Message: 1 > Date: Tue, 4 Aug 2009 14:40:04 +0200 > From: Siegfried-Angel > Subject: Re: Two packages form Ubuntu 8.04 (amd64) > To: Jean-Christophe Cazenave > Cc: ubuntu-devel-discuss@lists.ubuntu.com > Message-ID: > <357b51820908040540y7b957eaes56feb24c47879...@mail.gmail.com> > Content-Type: text/plain; charset=UTF-8 > > Hi, > > Thanks for your interest in contributing to Ubuntu. > > 2009/8/3 Jean-Christophe Cazenave : > >> glimpse: http://webglimpse.net , a tool for indexing text files in a tree of >> directories >> > > http://revu.ubuntuwire.com is the place for new packages. > > >> bash-4.0: my objective was to use associative arrays (the current man is >> currently based on bash-3.2 and doesn't tell anything about that, but >> the online documentation does: >> http://www.gnu.org/software/bash/manual/html_node/Arrays.html#Arrays). I >> have compiled it with the whole bunch of currrent patchs. >> > > Please get in touch with Debian's Bash maintainer about those patches. > > --- avast! Antivirus: Outbound message clean. Virus Database (VPS): 090805-1, 08/05/2009 Tested on: 8/6/2009 1:19:45 AM avast! - copyright (c) 1988-2009 ALWIL Software. http://www.avast.com -- Ubuntu-devel-discuss mailing list Ubuntu-devel-discuss@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss
