#27998 seems to have been merged with without any documentation.

There should be.

Short version how to use these features to get the ball rolling:

1. Make a new docker-compose.yml or port an existing one, with version: '3' explicitly specified. Seems the "schema" (layout of services, networks, etc. keys) did not change much in this new version but some parameters for services are unsupported. I'm guessing build: is likely not supported as well?
2. Run docker deploy --compose-file docker-compose.yml stackname.
3. docker stack can be used to view the generated services for the "stack" defined by the Docker Compose file. e.g., docker stack ls to view created stacks, docker stack services stackname to view the services associated with that stack, etc.

FYI @londoncalling @johndmulhausen