Hi,

On Thu, 2020-06-04 at 15:02 -0400, Matt Campbell wrote:
> I'm looking into RAUC for a product, and I was wondering if there are
> any project goals around the stability of the RAUC bundle format.
> Specifically, it would be great if all future versions of the rauc
> binary was compatible will all previous bundle formats, and also that
> all older versions of the binary can install future created bundles.
> Obviously that's a big ask, but it'd be great to know what to expect
> of RAUC in the future. Even a rough idea of how compatibility will
> play out will help me greatly in evaluating RAUC.

The basic bundle format has not changed so far (squashfs with
CMS
signature), which means that newer versions can install old bundles.
Going forward, any issue with installing old bundles would be
considered a bug.

Newer RAUC versions have introduced new features and slot types, though
(such as casync, emmc-boot partitions, MBR partition switching). If you
use those features, old versions of RAUC won't be able to install those
bundles. As long as you don't use new features, our intention is that
bundles created by newer versions will be installable by older
versions.

There are ideas of introducing a new bundle format to allow streaming
installation (over the network), but we won't remove support for the
original format.


If there are ever reasons that require an incompatible change, you can
use a two step migration:
You can use an intermediate update to ship a new RAUC binary in a
bundle created by the old version. Then use the newly installed RAUC
for the real update.


Does that answer your questions?

Regards,
Jan