Note: this doesn't quite work yet.
The OSD containers need to be started twice (the first time, they fail initializing; second time is a champ).
Also, it looks like you need at least two OSD containers (or the OSD container should have two disks/directories, whatever).
RadosGw is listening on port 8080.
The admin container will create a docker user using radosgw-admin.
If you run it multiple times, that's OK: further invocations are idempotent.
Last but not least: it looks like AWS CLI uses a new signature format that doesn't work with RadosGW. After almost two hours trying to figure out what was wrong, I tried the S3 credentials directly with boto and it worked immediately (I was able to create a bucket).