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Re: Comments on live-build, vmdebootstrap, bootstrap-vz, and live-wrapper

On Tue, Aug 30, 2016 at 11:07:33AM +0200, Thomas Goirand wrote:
> On 08/22/2016 01:29 PM, Adam Bolte wrote:
> I believe I could write it myself if:
> 1/ I had access to an AWS account. Can anyone help in this regard?

Amazon offers a free-of-charge trial, with no-cost access to one of
the micro instance types as I recall. That should suffice, and is
probably your best bet to get started, although I think you will need
a credit card.

> 2/ Someone just told me what's missing in the current image. Adam, could
> you give a quick summary of what's needed?

A good starting point would be the ec2 directory of
debian-image-builder, since that splits out the EC2-specific steps
reasonably well I think. Those files can be seen here:

Some of it is specific to EC2 image types, such as paravirtual Vs HVM
images, and EC2-backed Vs instance-backed images. I'm not sure if the
plan for openstack-debian-images is to support all possible EC2
instance types, or just the latest ones AWS recommends (albeit perhaps
not compatible with all existing environments).

debian-image-builder does no partitioning when building HVM images
since only paravirtual images existed when it was written. I would aim
to make sure that partitioning is properly taken care of for HVM
images when adding new code to openstack-debian-images.

As part of the creation process, I attach an EBS volume and install
GRUB on that to avoid some issues I had previously with
grub-install. Maybe that's no longer an issue, so should be re-tested
with the grub-install approach openstack-debian-images uses before
adding that code. My suspicion is that it won't be an issue when
partitioning for HVM images, and Jessie has the grub-xen package which
you can use to create a menu.lst / grub.conf file without needing to
run grub-install for paravirtual images.

Actually, the paravirtual update-grub approach taken in
debian-image-builder could use some improvement. For paravirtual
images, installing grub-xen, removing execute permission on everything
in /etc/default/grub/ except 10_linux, and setting
GRUB_DISABLE_SUBMENU="y" in /etc/default/grub should be enough to
cleanly generate a grub.conf file that's compatible with pygrub,
without the need for the 40_custom Grub script you can see I
deploy. But honestly I don't know if many people use paravirtual
images on AWS these days, and AWS was the main focus of my project
since that's what I use it for.

That's everything I can think of that's noteworthy. Let me know if you
have any questions.

> Since both OpenStack and AWS are using the EC2 metadata server, I'm
> convince that it should be possible (and even desirable) for Debian to
> ship a single image that would accommodate both. I'm willing to do
> so.

That sounds good. Although I personally use EC2 right now, I'd like to
see OpenStack supported as well.

Another tool to maybe take hints from is the xen-create-image script
included in the xen-tools package. It basically creates a Debian
paravirtual image. Written in Perl, but probably simple enough to
understand without much Perl knowledge. It's officially packaged for
Debian, and you can compare the image modifications it makes by


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