I believe it actually installs the Docker community edition (CE) which is under the Apache 2.0 license. Docker (the product) is assembled using the Moby libraries and components.
Correct, Moby is not a distribution of a container runtime.. it's not the "docker" you are looking for. Docker CE is and that's what's used in the guide.
Full Disclosure: I, Manik Taneja, am the Product Manager for all the open source efforts at Docker and work on the Moby Project.
As suggested here, the blog post only talks about installing the Docker Community Edition (CE) that is published under Apache 2.0 License. This is the official incarnation of the Docker Product and is provided to have:
- a consistent user experience across different linux distributions
- strong security guarantees
- regular bug fixes and updates
Moby Project serves as the upstream for the entire Docker Product and includes all open source components that make up Docker, such as runc, containerd, notary, moby, infrakit, linuxkit, libnetwork, hyperkit, vpnkit, datakit, etc.
It's my understanding that the bulk of the components that make Docker work are fully open source, and some extra support and deployment related things are the only things that are commercially licensed. This would include Docker Swarm, as it's a part of Docker itself and not something separate. IANAL though.
I'm pretty sure the reason they go for plain Docker over Moby is sheer ease of use. Despite being a bit weird to understand under the hood, Docker is just dead simple to get up and running with, and using the clustering mode that's built right in is easier to teach new readers than Moby, which from its Github page is obviously designed for folks that are already rather comfortable with Docker. Straight from Moby's Github page:
"Moby is NOT recommended for: Application developers looking for an easy way to run their applications in containers. We recommend Docker CE instead."