Where Docker adds real value is not (just) Docker Hub but Docker for Windows and Mac. The integrations offer a vastly superior experience than messing around with VirtualBox and Vagrant by hand (been there, done that) to achieve running Docker on one's development machine.
I lived through a failed attempt to migrate from Docker Desktop for Mac to an open source alternative (minikube+portainer, IIRC). A lot of test scripts developers relied on – to run parts of the integration test suite on their laptops for debugging – broke, because Docker Desktop for Mac went to a lot of effort to make macOS look like you were running Docker on Linux, whereas the open source replacement wasn't as seamless. Some of these test scripts contained Java code directly talking to the Docker daemon over its Unix domain socket, so need the same API implemented. Many other scripts made heavy use of the Docker CLI. After spending a lot of time on it, it was decided to just go back to Docker Desktop for Mac. The failed migration had resulted in highly paid engineers spending time pulling their hair out trying to get test scripts to work instead of actually fixing bugs and delivering new features.
Now, that was 2+ years ago now, and maybe the open source alternatives have caught up since, or maybe we picked the wrong one or made some other mistake. But I'm not rushing to try it again.
Similar issues in our environment, and I managed to swap everything over to Rancher Desktop fairly seamlessly as it does the exact same thing. It runs a Linux VM and if you select the "dockerd (moby)" container engine it runs a copy of docker inside of it. So you get a socket with the same docker API implemented... because it's running actual docker. docker compose and everything else work as expected.
The reason we switched is that Rancher Desktop, along with providing a convenient way to run docker, also includes a full k3s install in that same VM. So we can work on unifying some of our stack/configs on kubernetes rather than docker for local and kubernetes for everywhere else. It also opens up using upstream helm charts and things when a developer wants to deploy and try something locally.
It's also free. Open source and backed by SUSE, who also develops and maintains the k3s distribution among other stuff in this space.
Yes, but that wasn't what I was talking about. Docker Desktop for Mac goes to a lot of trouble to hide the fact that there are two different virtual filesystems involved (Linux vs macOS) and two different networking stacks too. That means scripts which run on Docker for Linux and do stuff involving filesystem/network integration between the host and the container will often work without change on Docker Desktop for Mac. In my past experience, open source alternatives don't offer as seamless integration, they don't do as good a job of hiding the fact that there are two different virtual filesystems and networking stacks, so those kinds of scripts are less likely to work.
FS: Rancher mounts your `/Users/$USER` folder in the VM that Docker is running in. It supports virtiofs on macos (not sure if it's used by default though). As far as I can tell, this replicates the default Docker Desktop setup.
Networking Container -> Host: Connecting to `host.docker.internal` works as expected. On the host I can listen on a port on my host (`nc -l -p 1234`) and connect from a container (`docker run -it --rm alpine nc host.docker.internal 1234`).
Networking Host -> Container: Exposed ports work as I would expect. I can run a container with an exposed port (`docker run -it --rm -p 1234:1234 alpine nc -l -p 1234`) and connect from my host (`telnet localhost 1234`). I can't connect directly onto the docker network bridge (though I'm not sure if that was ever supported on OSX?).
No skin in the game either way here, just with a bunch of people suggesting buying OrbStack (which is OSX only), figured I'd throw Rancher Desktop out as a potentially viable cross-platform alternative that's also free and OSS.