[haswell]

You've lost me. This sentence does not explain how Docker, or containers work.

It explains one aspect/limitation related to the execution of code in a container, but does not foster a deeper understanding of container architecture for the uninformed reader, and is actually somewhat misleading considering Docker's use of a VM behind the scenes in some situations (in which case the "host running the container" is technically the VM, not the user's PC).

I sense that you have useful knowledge to share. I'm afraid you've missed the mark. Instead of spreading vitriol and asking why everyone around you is so dumb, focus that energy on sharing that knowledge!

[stephenr]

> considering Docker's use of a VM behind the scenes in some situations (in which case the "host running the container" is technically the VM, not the user's PC).

That is exactly the point. If you want to run Linux binaries you need a Linux container. On windows or macOS that means a Linux vm.

If you want to run windows binaries you need a windows container.

Conversely if you had a macOS container you’d only be able to run macOS binaries.

This is my point. It’s not a hard concept to understand. I’m not asking people to learn about cgroups or Chroots or network namespaces or any of that.

[geofft]

One, it might be totally fine to run macOS binaries! If your code is portable to macOS and Windows, you might still want to use Docker for dependency management, network isolation, orchestration of multiple processes, etc., but you might not care what the actual host OS is. (Just like how people are interested in running ARM binaries, even though Docker started out as x86-64.) At my day job, all the stuff we put in Docker is either Python (generally portable), Java (generally portable), or Go (built-in cross-compilation support). It's absolutely sensible to do local dev on a Mac and then deploy on Linux in prod - it's perfectly sensible to do so without Docker in the picture, and plenty of people do just that.

So, maybe all the people you're yelling at understand the concept you think they don't, and they're okay with it.

Two, it's not at all true that to run Linux binaries on non-Linux, you need a Linux VM. WSL1 is an existence proof against this on Windows, as is the Linuxulator on FreeBSD, as are LX-branded zones on SmartOS. Linux itself has a "personality" mechanism for running code from non-Linux UNIXes. You could do the same thing on macOS, and teach the kernel to handle a good-enough subset of the Linux system call interface - it would be far less work than adding containerization (namespacing and resource isolation) in the first place, so I'm not sure why you're so hung up about this.

[stephenr]

> Two, it's not at all true that to run Linux binaries on non-Linux, you need a Linux VM.

So (a), this entire thread, the entire post, is about docker. (b) WSL1 worked so well, Microsoft not lonely abandoned that approach for WSL2, they also never used that approach for containers on Windows. Hence, Windows native containers are, drum roll... Windows.