title: Gitlab runner Docker executor does not connect to postgres service
body: <p>I am successfully let <code>runner</code> be able to do <code>git clone</code> in order to install <code>Django</code> dependencies. Now I am solving next problem. It is <code>Postgres</code></p>
  
  <p>My ultimate goal is <code>pytest</code>, but for now I will test <code>gitlab-ci</code> script with <code>python manager.py test</code>.</p>
  
  <pre><code>Successfully installed appnope-0.1.0 boto3-1.4.7 botocore-1.7.47 certifi-2017.11.5 chardet-3.0.4 collectfast-0.5.2 decorator-4.1.2 django-1.11.7 django-choices-1.6.0 django-cors-headers-2.1.0 django-countries-5.0 django-debug-toolbar-1.9.1 django-dirtyfields-1.3 django-environ-0.4.4 django-extensions-1.9.7 django-filter-1.1.0 django-geoposition django-guardian-1.4.9 django-money django-reversion-2.0.10 django-s3-folder-storage-0.5 django-storages-1.6.5 djangorestframework-3.7.3 djangorestframework-jwt-1.11.0 docutils-0.14 freezegun-0.3.9 gevent-1.2.2 greenlet-0.4.12 gunicorn-19.7.1 idna-2.6 ipython-6.2.1 ipython-genutils-0.2.0 jedi-0.11.0 jmespath-0.9.3 model-mommy-1.4.0 olefile-0.44 parso-0.1.0 pexpect-4.3.0 pickleshare-0.7.4 pillow-4.3.0 prompt-toolkit-1.0.15 psycopg2-2.7.3.2 ptyprocess-0.5.2 py-1.5.2 py-moneyed-0.7.0 pygments-2.2.0 pyjwt-1.5.3 pytest-3.2.5 pytest-django-3.1.2 python-dateutil-2.6.1 pytz-2017.3 requests-2.18.4 rest-framework-generic-relations-1.1.0 s3transfer-0.1.11 simplegeneric-0.8.1 six-1.11.0 sqlparse-0.2.4 traitlets-4.3.2 typing-3.6.2 urllib3-1.22 wcwidth-0.1.7 werkzeug-0.12.2
  $ python manage.py test
  /usr/local/lib/python3.6/site-packages/django/db/backends/postgresql/base.py:267: RuntimeWarning: Normally Django will use a connection to the 'postgres' database to avoid running initialization queries against the production database when it's not needed (for example, when running tests). Django was unable to create a connection to the 'postgres' database and will use the default database instead.
    RuntimeWarning
  Creating test database for alias 'default'...
  Traceback (most recent call last):
    File "/usr/local/lib/python3.6/site-packages/django/db/backends/base/base.py", line 213, in ensure_connection
      self.connect()
    File "/usr/local/lib/python3.6/site-packages/django/db/backends/base/base.py", line 189, in connect
      self.connection = self.get_new_connection(conn_params)
    File "/usr/local/lib/python3.6/site-packages/django/db/backends/postgresql/base.py", line 176, in get_new_connection
      connection = Database.connect(**conn_params)
    File "/usr/local/lib/python3.6/site-packages/psycopg2/__init__.py", line 130, in connect
      conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
  psycopg2.OperationalError: could not connect to server: Connection refused
      Is the server running on host "localhost" (127.0.0.1) and accepting
      TCP/IP connections on port 5432?
  could not connect to server: Cannot assign requested address
      Is the server running on host "localhost" (::1) and accepting
      TCP/IP connections on port 5432?
  </code></pre>
  
  <p><code>.gitlab-ci.yml</code></p>
  
  <pre><code>image: python:3.6
  services:
    - postgres:latest
  
  variables:
    POSTGRES_DB: poinkdb
    POSTGRES_USER: postgres
    POSTGRES_PASSWORD: postgres
  
  before_script:
    - 'which ssh-agent || ( apt-get update -y &amp;&amp; apt-get install openssh-client -y )'
    - eval $(ssh-agent -s)
    - echo "$SSH_PRIVATE_KEY" | tr -d '\r' | ssh-add - &gt; /dev/null
    - mkdir -p ~/.ssh
    - chmod 700 ~/.ssh
    - ssh-keyscan github.com &gt;&gt; ~/.ssh/known_hosts
    - chmod 644 ~/.ssh/known_hosts
    - git config --global user.email "sarit@elcolie.com"
    - git config --global user.name "sarit"
    - python -V
    - pip install -r requirements.txt
  
  test:
    tags:
      - poink
      - Elcolie
    script:
    - sleep 10
    - python manage.py test
  </code></pre>
  
  <p><strong>FYI:</strong><br>
  I have searched on docker and postgres gitlab-ci. But found irrelevant topic. They are docker networking between Django and Postgres and put the config to single <code>docker-compose</code>. I know <code>docker-compose</code>. I have been using it for a year.</p>
  
  <p>But they are not my case. I am asking inside the <code>runner</code>.</p>
  
  <p><strong>References:</strong><br></p>
  
  <p><a href="https://medium.com/pyslackers/setting-up-tests-in-gitlab-ci-for-django-project-with-docker-engine-44f01940424d" rel="nofollow noreferrer">https://medium.com/pyslackers/setting-up-tests-in-gitlab-ci-for-django-project-with-docker-engine-44f01940424d</a><br>
  <a href="https://github.com/gitlabhq/gitlabhq/blob/master/vendor/gitlab-ci-yml/Django.gitlab-ci.yml" rel="nofollow noreferrer">https://github.com/gitlabhq/gitlabhq/blob/master/vendor/gitlab-ci-yml/Django.gitlab-ci.yml</a></p>
  
  <p><strong>Solution:</strong><br>
  @dvnguyen To remind I myself in the next time.</p>
  
  <pre><code>test:
    tags:
      - poink
      - Elcolie
    variables:
      DATABASE_URL : "postgres://postgres:postgres@postgres:5432/poinkdb"
    script:
    - python manage.py test
  </code></pre>