[Maas-devel] Forward compatibility of subarches (was Re: Problems with the hwe work)

[Jeroen Vermeulen]

On 05/12/2014 06:33 AM, Julian Edwards wrote:

> I suspect we don't really need to have that separate scan any more, we
> can just report via the API after m-i-p-f knows it has downloaded them.

It would give us some more information that we've been wanting,
including “where did I get this image?”

We'll want to report downloads per image, instead of once at the end, to
preserve ‘eventual-consistency.’  Recognition of completed image
downloads will require a bit of extra bookkeeping: the import code
thinks mostly in terms of files, and an image can have several files.

There will be a new failure scenario — “download succeeds but report
fails.”  Later runs should at least re-report the image.  For best
progress in the face of repeated failures however, it would still be
good to keep and re-use files that were successfully downloaded.

Luckily the refactored import code gives us documented access to the
information we need — even after the fact for images that were imported
using older code!


Jeroen