I'm aware of the WSL dependency for the Windows version of Docker - I dealt with it 5 days a week for 4 years before I switched to Ubuntu as my work OS this January. When I said "Docker runs fine on Windows," I meant that Microsoft already ships the necessary runtime to host a Docker container.
I can't comment on MacOS as I haven't used it regularly in several years, and even then I only used Docker briefly on MacOS.
I can see how this approach would result in reliably cross-platform applications, but it immediately raises a couple of concerns: binary size, and interoperability with the underlying OS.
Docker on its own can already be very large. Shoving it inside of QEMU adds even more largeness. Are binary sizes a priority at all? If so, how do you plan to keep them reasonably compact?
I'll assume that user-facing software is the main target for this tool, which means that GUI support is really important. By hosting an application inside of QEMU and Docker, you create a very long and complicated path that stuff must travel through in order for a dockerc'd GUI application to interact with other programs. It's pretty easy to plumb an X server into WSL, but there are limitations when you get into more nuanced interactions with the rest of the machine (ex: clicking and dragging files into the window). Docker adds yet another layer that could cause trouble.
I wish you luck. I tried to make a similar tool for a game engine a while back, and it was absolutely hellish.
I can't comment on MacOS as I haven't used it regularly in several years, and even then I only used Docker briefly on MacOS.
I can see how this approach would result in reliably cross-platform applications, but it immediately raises a couple of concerns: binary size, and interoperability with the underlying OS.
Docker on its own can already be very large. Shoving it inside of QEMU adds even more largeness. Are binary sizes a priority at all? If so, how do you plan to keep them reasonably compact?
I'll assume that user-facing software is the main target for this tool, which means that GUI support is really important. By hosting an application inside of QEMU and Docker, you create a very long and complicated path that stuff must travel through in order for a dockerc'd GUI application to interact with other programs. It's pretty easy to plumb an X server into WSL, but there are limitations when you get into more nuanced interactions with the rest of the machine (ex: clicking and dragging files into the window). Docker adds yet another layer that could cause trouble.
I wish you luck. I tried to make a similar tool for a game engine a while back, and it was absolutely hellish.