[ProgClub programming] VM won't boot after salt config

John Elliot V | ProgClub jj5 at progclub.org
Sun Jun 30 18:42:27 AEST 2019


On 30/6/19 9:06 am, Jedd Rashbrooke wrote:
>  It sounds like you haven't completed RCA yet, but contributing factors
> appear to be:
> 
>  No off-box archives available  to examine /etc/ deltas between points
> in time

Actually that's not true. I copied a 'clean' virtual disk and mounted it
with qemu-nbd before applying the salt config and then applied my salt
config. I then looked for deltas between the clean image and the broken
image, which is how I diagnosed the issue.

>  No change control - no testing of config changes before, or even after,
> pushing them out

Actually that's not true. This problem surfaced on a test system prior
to production rollout.

>  A bit of a misunderstanding about the difference between
> GRUB_CMDLINE_LINUX and ~_DEFAULT  (you said you 'changed' the parameter
> name, not just the parameter).

Sorry, I made a mistake there. That was a typo. The only relevant
setting was GRUB_CMDLINE_LINUX_DEFAULT, not GRUB_CMDLINE_LINUX.

>  An attachment to running GUIs on virtual machines which *probably*
> should be headless.  Slightly related --  most 'grub maybe-ubiquity'
> searches on the net reveal this is another way that Ubuntu has annoyed a
> good number of its users.  As noted elsewhere, GUIs on VMs that don't
> need them needlessly increase attack vector, consume resources, and now,
> in this case, add an extra set of components that can break your machine

I do run the servers headless, but not during installation as the
installer is interactive. In future I will be able to provision VMs
non-interactively by cloning a base image, but that requires a little
configuration I haven't done yet. If you're interested my current
scripts are here:

 https://svn.jj5.net/jjrepo/jj5-bin/branches/0.2/bin/vm-new

and here:

 https://svn.jj5.net/jjrepo/jj5-bin/branches/0.2/bin/vm-exp

> It's been 3 months since the last time a grub change (details weren't
> specified IIRC) rendered your GUI'd virtual machine unbootable, and
> distracted you from something useful while you spent a day hunting down
> the problem.

Yes, I knew I'd seen this problem before, but I had forgotten the
details. I've tried to log more specifics this time around in the hope I
will be able to find the solution faster if this happens to me again.

May the Force be with you,
John Elliot V
-- 
|_|O|_| ProgClub
|_|_|O| Because every programmer needs a good club!
|O|O|O| https://www.progclub.org/
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