[Bug 1060404] Re: update-grub runs and fails in containers

[Serge Hallyn]

** Description changed:

- ==============================
- SRU justification for lxc part:
- 1. Impact: update-grub fails, causing apt-get updates to fail if there is a new kernel.
- 2. Development fix: modify ubuntu templates to mount devtmpfs before starting container
- 3. Stable fix: same as development fix.
- 4. Test case:
- 	sudo lxc-create -t ubuntu-cloud -n q1
- 	sudo lxc-start q1
- 	# inside the container, run sudo update-grub
- 5. Regression potential: This adds one more mount per container (by default, removable), taking up more memory.
- ==============================
- If grub is installed in a container (as happens, for instance, with the ubuntu-cloud template) then an update of grub or linux-image will cause update-grub to be run.  It tries, finds it can't access the root device, fails, and causes the update to fail.
+ [XXX edit - removed the SRU justification for lxc part.  The proposed solution
+ was not safe, and was undone in a later commit.  devtmpfs cannot be mounted
+ in a container, because changes under the container's /dev are then
+ reflected in the host's /dev.
+ 
+ If grub is installed in a container (as happens, for instance, with the
+ ubuntu-cloud template) then an update of grub or linux-image will cause
+ update-grub to be run.  It tries, finds it can't access the root device,
+ fails, and causes the update to fail.
  
  It would be better for update-grub to detect that it is in a container
  and simply exit 0, so that the apt-get can succeed.  I'm attaching a
  debdiff which does that.

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https://bugs.launchpad.net/bugs/1060404

Title:
  update-grub runs and fails in containers

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