Main steps

install docker and docker-compose
note that folder sharing is required, since this docker image depends on the phabricator repository from developer.blender.org to be cloned into the right location (initialize.py should take care of that)
on Linux ensure the user you run docker with is in in the docker group: sudo usermod -aG docker $USER. Don't forget to logout and back in
clone https://github.com/jesterKing/phabricator
check out blender_phabricator_docker
cp settings_config.py.template settings_config.py
run the initialize.py script (python 3.5 minimum)
update /etc/hosts as suggested by initialize.py example: 192.168.1.100 phab.test.int
note that initialize.py suggests a number of steps to get config applied
- change PHABRICATOR_HOST=phab.test.int:62080 if you use a different domain name
docker-compose up or for running in background docker-compose up -d
browse to http://phab.test.int:62080
to use command-line access in your phabricator container
- docker exec -it phab_container_id bash
- this gives you an interactive bash as root into the container
- use su - git to become the phabricator user on the container
- git user has home at /srv/phabricator

Steps to set up policies and reconfigure

To get set up the policies properly you'll have to work around a bit of chicken and egg problem:

Do all of the steps above
Log into your phabricator instance
Create the policies and note their PHIDs (it is useful to enable developer settings where such data is always easily accessible while using your phabricator in the browser)
Set the PHIDs to the respective policy variables in settings_config.py
In your docker instance bash shell ensure the settings are visible
run the apply_config.py script again

ROOT will be your clone of the docker repository clone

The location of the phabricator clone is

ROOT/srv/docker/phabricator/phabricator

The location of the MySQL database files is

ROOT/srv/docker/phabricator/mysql

Use a Linux distribution that is more commonly used among Blender developers instead of OpenSuse
Complete blender-conduit.py to pull a usable subset of data from developer.blender.org to seed the docker instance with
Automate setting up of policies the when the database needs to be initialized (either very first run, or database location was cleared