Gitlab runner Docker executor does not connect to postgres service

I am successfully let runner be able to do git clone in order to install Django dependencies. Now I am solving next problem. It is Postgres

My ultimate goal is pytest, but for now I will test gitlab-ci script with python manager.py test.

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?

.gitlab-ci.yml

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 && apt-get install openssh-client -y )'
  - eval $(ssh-agent -s)
  - echo "$SSH_PRIVATE_KEY" | tr -d '\r' | ssh-add - > /dev/null
  - mkdir -p ~/.ssh
  - chmod 700 ~/.ssh
  - ssh-keyscan github.com >> ~/.ssh/known_hosts
  - chmod 644 ~/.ssh/known_hosts
  - git config --global user.email "[email protected]"
  - git config --global user.name "sarit"
  - python -V
  - pip install -r requirements.txt

test:
  tags:
    - poink
    - Elcolie
  script:
  - sleep 10
  - python manage.py test

FYI:
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 docker-compose. I know docker-compose. I have been using it for a year.

But they are not my case. I am asking inside the runner.

References:

https://medium.com/pyslackers/setting-up-tests-in-gitlab-ci-for-django-project-with-docker-engine-44f01940424d
https://github.com/gitlabhq/gitlabhq/blob/master/vendor/gitlab-ci-yml/Django.gitlab-ci.yml

Solution:
@dvnguyen To remind I myself in the next time.

test:
  tags:
    - poink
    - Elcolie
  variables:
    DATABASE_URL : "postgres://postgres:postgres@postgres:5432/poinkdb"
  script:
  - python manage.py test