Create a data-only container from Busybox (very small footprint) and name it "pgsql_data":
docker run -v /data --name=pgsql_data -d busybox echo "pgsql data"
You could use any image you what, but I made one that is derivated from paintedfox/postgresql and make some bugs corrections
docker run -d --name=postgresql -e USER="super" -e DB="software_db" -e PASS="p4ssw0rd" \
--volumes-from pgsql\_data atende/postgresql
This will create a postgresql container and the contents of the database will be separated from the postgres instance. It will also create a user named super with the password p4ssw0rd and a database named software_db. Change to whatever you like. The user is a super user.
If you plan to run other applications in the same host, I recommend create the
users and databases after. That way the user will not be a database super user.
By default the postgresql container create a user called super, you can check
its random password with the command docker logs postgresql.
A quick way to do that could be:
docker exec -i -t postgresql bash # login to the container
su postgres
psql # login to the database
create role software_user with login;
alter user software_user with encrypted password 'p4ssw0rd';
create database software_db owner software_user;