The mdillon/postgis image provides a Docker container running Postgres 9 with PostGIS 2.2 installed. This image is based on the official postgres image and provides variants for each version of Postgres 9 supported by the base image (9.1-9.5).
This image ensures that the default database created by the parent postgres image will have the following extensions installed:
postgispostgis_topologyfuzzystrmatchpostgis_tiger_geocoder
Unless -e POSTGRES_DB is passed to the container at startup time, this database will be named after the admin user (either postgres or the user specified with -e POSTGRES_USER). If you would prefer to use the older template database mechanism for enabling PostGIS, the image also provides a PostGIS-enabled template database called template_postgis.
In order to run a basic container capable of serving a PostGIS-enabled database, start a container as follows:
docker run --name some-postgis -e POSTGRES_PASSWORD=mysecretpassword -d mdillon/postgis
For more detailed instructions about how to start and control your Postgres container, see the documentation for the postgres image here.
Once you have started a database container, you can then connect to the database as follows:
docker run -it --link some-postgis:postgres --rm postgres \
sh -c 'exec psql -h "$POSTGRES_PORT_5432_TCP_ADDR" -p "$POSTGRES_PORT_5432_TCP_PORT" -U postgres'
See the PostGIS documentation for more details on your options for creating and using a spatially-enabled database.