Debugging the installer on Debian Live

I’ve been using this process for debugging the installer while launched from a Debian Live desktop. Having a full live environment at your disposal during install is a boon to debugging because you don’t have to work within the constraints normally imposed upon you by the limited debian-installer environment. Caveat: running debian-installer from the debian-installer-launcher still has one or two unresolved issues, so unless you’re specifically working on live integration issues like I am, compare with a conventional d-i image install to gain the added confidence the install is the same in both environments.

There are no longer active maintainers working on debian-installer-launcher and live-installer, and I think it’s really important for wheezy to release with solid support for live installs, so I’ve been using this setup to try to solve #702335. So far, progress is slow because I’m new to this. If anyone is interested in collaborating in this work, give me a shout. I am SynrG @ irc.oftc.net and can be found on #debian-live and #debian-boot if you would like to drop in.

Overview:

  1. Use images/lxde-desktop config from live-images.git and build your own image with live-build >=3.0.1-1. Just add “-b hdd” in auto/config before starting your build, as having a read/writable image is handy for this exercise.
  2. Boot the live medium. You may prefer to do this in a VM for convenience, having prepared a blank virtual disk image as your target in advance.
  3. Make any small changes you want to the installer before launching it.  A quick hack I’ve used is to “sudo vi /usr/sbin/debian-installer-launcher” and near the end on the line after “prepare” right before “run”, open a new line and add “bash” so an interactive shell will be opened after the installer is extracted but before it is launched. For larger changes (e.g. inclusion of updated udebs, etc.) add them to your live image configuration before building as described in live-manual.
  4. Open two root terminals and do “debian-installer-launcher -t debug” in one and “tail -f /lib/live/installer/var/log/syslog” in the other. If you’ve added the hack from step 3, don’t forget to “exit” the interactive shell after making changes. Now you can watch debug output as you go through the steps of the installer. If you like, you may append additional boot prompt parameters (e.g. preseeds) to the debian-installer-launcher command.
  5. During the install, you may modify other parts of the unpacked installer under /lib/live/installer (e.g. to add ‘set -x’ to some scripts) prior to executing steps that would call them.

8 thoughts on “Debugging the installer on Debian Live”

  1. I used to make heavy use of the debian live installer until I ran into a bug. The images seem to be broken from 6.0.2 on stating that grub has failed to install. Luckily I found an archive of 6.0.1 images. I hope you gather enough interest to get the live installer working again!

  2. Samuel, if you’re impatient to try, you could boot one of the wheezy rc1 images (at http://live.debian.net/cdimage/release/next/ or http://live.debian.net/cdimage/release/next+nonfree/), install debian-installer-launcher 15 (just uploaded to sid, appearing at your mirror soon) on it and the start the launcher. Debian Live’s wheezy rc2 release (soonish) will include this version if you would prefer to wait.

    Please note that in addition to the bug mentioned in the article, the rc1 images linked above are also afflicted by #702226, rendering the launcher completely unusable until you upgrade it to version 15.

  3. By the way, I’d really like to have a bug report filed for the grub thing. I’m told it still affects the wheezy rc1 image but nobody has furnished me with an easily reproducible failing case nor filed a bug on it yet, and I’ve not been able to reproduce it myself on rc1 or later.

  4. Hi Ben,

    My apologies I took so long to get back to you. I will download the latest gnome live image of wheezy and try to install normally. After which I will upgrade the debian-installer-launcher and try again and report any changes. I will record a screencast of the installation so I can easily document my experience.

    All I know so far is the installation fails reliably for me on the 6.0.2 and up images when I click the launcher from the desktop. My memory is unclear if I have the same bug when I boot directly into the installer. Hopefully my report will assist the developers.

    Thanks,
    Sam

  5. Sam, I’d really appreciate that. Of course, we are working on borrowed time now, so if there are serious problems remaining in the launcher, I need to promptly find solutions to have a chance of making the release. Otherwise, it would be better to release without the launcher at all.

    Thanks,
    Ben

  6. I updated to the version 15 debian-installer-launcher during the live session, and successfully completed the installation without having the grub error. So it seems that problem is fixed! The only problem I encountered was that the gnome screensaver started during the install when I left it idle. I guessed the password was ‘live’ but I can’t expect everyone to know that.

    The image also only let me install using the ’486′ kernel, it gave me a warning when I tried to use 686-pae. Though I assume that is normal (and obviously not an issue on amd64).

    Is there anything you would like me to test or add to a bug report? I can’t report any oddities other than what I have noted here.

  7. Sam,

    Glad to hear you’ve had no GRUB issues. That being said, I’m still a bit nervous about that as I had one report on irc from a user who claimed to still have issues with rc1 + debian-installer-launcher 15. I have a suspicion that it may have to do with certain d-i partitioning choices (encryption, lvm) but have not yet had a chance to test this theory, so there’s one place you could help.

    As for the screensaver, that’s supposed to be disabled by live-config and should be fixed in rc2.

    The kernel mismatch error is indeed normal. I’m not sure if/how we could make it clearer, but I believe d-i will do the right thing and install an appropriate kernel even though you need to always boot the 486 to make the installer work.

    You’ll find debian-installer-launcher 15 has migrated to testing now, and I have also uploaded version 16 and requested an unblock for it (see #704273). I have tested 16 in these flavours: lxde, standard, and xfce. It could use some more testing with other image flavours.

    Finally, I’m going to tackle #704065 next. I’m still not clear on what’s going on here, whether it is some issue in the environment of the installer or else user error.

    Thanks for the help testing,
    Ben

  8. I cannot stress enough how important it is to use version 16 or later now, as it solves the grave bug #703979 which can cause data loss, as you pointed out to me today in email, Sam. Once again, my humble apologies for having gotten bitten by this. To anyone else reading these comments: the damage might not simply affect /target, but also other partitions not flagged as to be used by the installer, so exercise extreme caution and only use version 16 or later!

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