Re: Difference between Debian cloud images: openstack/generic/genericcloud
On 3/31/21 4:18 PM, Vitaly Potyarkin wrote:
> I'm trying to understand the differences in content and support status of
> Debian cloud images found here [1]. It seems to me that Openstack, generic and
> genericcloud serve more or less the same purpose - and I'm failing to
> understand when to use which.
>
> Here is what I've gathered so far:
>
> - Openstack image seems to be the go to one for all use cases, even outside of
> Openstack deployments. It also has a more "official" vibe to it, being
> grouped into the same section as CD/DVD installer images at this page [2]
>
> - Generic and genericcloud images are listed under "misc and unofficial stuff"
> at [2] and provide no stable URLs for the latest build - that suggests these
> images are somehow inferior to the Openstack ones.
>
> - Image size differs drastically between Openstack (535M) and generic (285M),
> genericcloud (222M) images. Package list diffs show that openstack adds
> some packages like aptitude, python2.7 and firmware-linux-free - but I'm not
> sure that those are enough to account for the twice larger size, especially
> since generic/genericcloud add some packages too (bridge-utils, curl,
> chrony, man-db, manpages, ethtool, etc). Maybe there are some differences in
> the build process?
>
> - The only difference between generic and genericcloud seems to be the kernel:
> linux-image-amd64 in generic and linux-image-cloud-amd64 in genericcloud.
> For some reason the -cloud kernel is significantly smaller, even though
> package description [3] makes no mention of omitted modules (drivers?)
>
> My use case is pretty simple: I'm just looking for a base image to spawn new
> virtual machines under libvirt/kvm with cloud-init. I'm inclined to go with
> smaller genericcloud images, but I'm a little worried that there are some
> hidden footguns I'm not aware of. Wiki page [4] has no mention of generic
> cloud images, could someone knowledgeable explain the differences please?
>
> [1]: http://cloud.debian.org/images/cloud/
> [2]: https://cdimage.debian.org/cdimage/
> [3]: https://packages.debian.org/buster/linux-image-4.19.0-16-cloud-amd64
> [4]: https://wiki.debian.org/Cloud/
>
Hi,
Indeed, the build process is very different. The OpenStack images are
build using:
https://packages.debian.org/openstack-debian-images
wile the Generic/Genericcloud iamges are build using FAI.
Inded, the choice of binaries are a bit different too.
I'm currently also worried about the URL scheme for the generic images.
This was supposed to be addressed by the cloud image finder, but it
never got to a point where it is useful. Hopefully, this may be
addressed later on. I'm currently thinking about rewriting all from
scratch, since I'm not getting enough support from the original
maintainer. This should be discussed with the team, I guess.
As for Generic vs Genericcloud, indeed, what changes is the kernel. The
idea behind the Generic image is that the image can be used with Ironic,
on baremetal hardware, where the Genericcloud may not.
I hope this helps,
Cheers,
Thomas Goirand (zigo)
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