> If multi platform images work, a lot of the concerns people have about x86 versus ARM should go away.
Not really. Just because you have ARM and AMD debian, you wouldn't have same behaviour in both. You wouldn't have same list of packages that can be installed.
You'll have extremely close to the same behaviour in both since Debian ships exactly the same versions. It's always possible that there's a compiler bug which only affects one platform but that's relatively uncommon. At one point I was supporting Debian on x86, x86_64, MIPS, and PowerPC. The major portability concern was drivers, which is irrelevant for Docker, and sometimes you'd find performance issues with e.g. OpenSSL having a hand-tuned x86 ASM implementation but relying on the C compiler for another platform but it was rather uncommon.
I am skeptical that anyone will notice a problem unless their workflow is to build a container on their laptop and push it straight to production without testing.
That is fundamentally what I mean when I say "If they work". If the two platforms behave differently, then multi-platform images are pointless.
If 1 in 20 multi-platform images has some kind of oddball cross platform behavior, developers won't be able to rely on them at all. I think we can get far better than that, but we'll see.
Not really. Just because you have ARM and AMD debian, you wouldn't have same behaviour in both. You wouldn't have same list of packages that can be installed.