[jillesvangurp]

It exists but in terms of people using it or it being actively developed, it's dead as a doornail ever since Docker was more less forced to also support kubernetes and basically gave in to the reality that world + dog was opting for kubernetes instead of swarm.

They never really retired it but at this point it's a footnote in Docker releases.

I've not actually encountered it in the wild in four years or so and never in a production setup.