This is a "Dockerized" version of the install described here for Ubuntu / Debian systems: http://postgis.net/install/
(As of 5/16/17: http://trac.osgeo.org/postgis/wiki/UsersWikiPostGIS23UbuntuPGSQL96Apt ) The adminpack extension is enabled in the default postgres database. PostGIS recommends never installing itself into the default db, postgres, so a separate database, gisdb, is created with schema 'postgis' and that db has the postgis, pgrouting and postgis_sfcgal extensions installed.
Vim is included as a convenience.
docker run --name postgis -e POSTGRES_PASSWORD=postpass -p 5432:5432 -d jjglyn/postgis
Extending this image to create tables, data, etc. can be done by adding .sql or .sh files to the /docker-entrypoint-initdb.d directory.