Docker, Django and Selenium - Selenium unable to connect

Question

I have Docker configured to run Postgres and Django using docker-compose.yml and it is working fine.

The trouble I am having is with Selenium not being able to conne

Answer 1

I ended up coming up with a better solution that didn't require me to hardcode the IP Address. Below is the configuration I used to run tests in django with docker.

Docker-compose file

# docker-compose base file for everything
version: '2'

services:
  postgis:
    build:
      context: .
      dockerfile: ./docker/postgis/Dockerfile
    container_name: postgis
    volumes:
      # If you are using boot2docker, postgres data has to live in the VM for now until #581 fixed
      # for more info see here: https://github.com/boot2docker/boot2docker/issues/581
      - /data/dev/docker_cookiecutter/postgres:/var/lib/postgresql/data

  django:
    build:
      context: .
      dockerfile: ./docker/django/Dockerfile
    container_name: django
    volumes:
      - .:/app
    depends_on:
      - selenium
      - postgis
    environment:
      - SITE_DOMAIN=django
      - DJANGO_SETTINGS_MODULE=settings.my_dev_settings
    links:
      - postgis
      - mailcatcher

  selenium:
    container_name: selenium
    image: selenium/standalone-firefox-debug:2.52.0
    ports:
      - "4444:4444"
      - "5900:5900"

Dockerfile (for Django)

ENTRYPOINT ["/docker/django/entrypoint.sh"]

In Entrypoint file

#!/bin/bash
set -e

# Now we need to get the ip address of this container so we can supply it as an environmental
# variable for django so that selenium knows what url the test server is on
# Use below or alternatively you could have used
# something like "$@ --liveserver=$THIS_DOCKER_CONTAINER_TEST_SERVER"

if [[ "'$*'" == *"manage.py test"* ]]  # only add if 'manage.py test' in the args
then
  # get the container id
  THIS_CONTAINER_ID_LONG=`cat /proc/self/cgroup | grep 'docker' | sed 's/^.*\///' | tail -n1`
  # take the first 12 characters - that is the format used in /etc/hosts
  THIS_CONTAINER_ID_SHORT=${THIS_CONTAINER_ID_LONG:0:12}
  # search /etc/hosts for the line with the ip address which will look like this:
  #     172.18.0.4    8886629d38e6
  THIS_DOCKER_CONTAINER_IP_LINE=`cat /etc/hosts | grep $THIS_CONTAINER_ID_SHORT`
  # take the ip address from this
  THIS_DOCKER_CONTAINER_IP=`(echo $THIS_DOCKER_CONTAINER_IP_LINE | grep -o '[0-9]\+[.][0-9]\+[.][0-9]\+[.][0-9]\+')`
  # add the port you want on the end
  # Issues here include: django changing port if in use (I think)
  # and parallel tests needing multiple ports etc.
  THIS_DOCKER_CONTAINER_TEST_SERVER="$THIS_DOCKER_CONTAINER_IP:8081"
  echo "this docker container test server = $THIS_DOCKER_CONTAINER_TEST_SERVER"
  export DJANGO_LIVE_TEST_SERVER_ADDRESS=$THIS_DOCKER_CONTAINER_TEST_SERVER
fi


eval "$@"

In your django settings file

SITE_DOMAIN = 'django'

Then to run your tests

docker-compose run django ./manage.py test