Celery can't connect to local PostgreSQL from within Docker container

I have a Django-Celery-PostgreSQL project that should partially run in Docker. Having Redis and PostgreSQL servers running locally on the machine and using virtual environment for the project everything runs smoothly. But when I try to setup Docker instance Celery seems unable to connect to the Postgres database while Django can.

When running project in Docker I put only Django and Celery in it and set network_mode: "host". Redis and Postgres remains on the local machine. Django server itself works flawlessly reading and writing data into the Postgres database, but when I try to run Celery tasks - I get following exception (thrown by django_celery_results):

[2019-08-13 11:26:24,815: ERROR/MainProcess] Pool callback raised exception: OperationalError('could not connect to server: No such file or directory\n\tIs the server running locally and accepting\n\tconnections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?\n',)
Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/base/base.py", line 217, in ensure_connection
    self.connect()
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/base/base.py", line 195, 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 178, in get_new_connection
    connection = Database.connect(**conn_params)
  File "/usr/local/lib/python3.6/site-packages/psycopg2/__init__.py", line 126, in connect
    conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
psycopg2.OperationalError: could not connect to server: No such file or directory
        Is the server running locally and accepting
        connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?


The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/billiard/pool.py", line 1750, in safe_apply_callback
    fun(*args, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/celery/worker/request.py", line 371, in on_failure
    store_result=self.store_errors,
  File "/usr/local/lib/python3.6/site-packages/celery/backends/base.py", line 160, in mark_as_failure
    traceback=traceback, request=request)
  File "/usr/local/lib/python3.6/site-packages/celery/backends/base.py", line 342, in store_result
    request=request, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/django_celery_results/backends/database.py", line 38, in _store_result
    using=using,
  File "/usr/local/lib/python3.6/site-packages/django_celery_results/managers.py", line 50, in _inner
    return fun(*args, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/django_celery_results/managers.py", line 129, in store_result
    defaults=fields)
  File "/usr/local/lib/python3.6/site-packages/django/db/models/query.py", line 538, in get_or_create
    return self.get(**kwargs), False
  File "/usr/local/lib/python3.6/site-packages/django/db/models/query.py", line 402, in get
    num = len(clone)
  File "/usr/local/lib/python3.6/site-packages/django/db/models/query.py", line 256, in __len__
    self._fetch_all()
  File "/usr/local/lib/python3.6/site-packages/django/db/models/query.py", line 1242, in _fetch_all
    self._result_cache = list(self._iterable_class(self))
  File "/usr/local/lib/python3.6/site-packages/django/db/models/query.py", line 55, in __iter__
    results = compiler.execute_sql(chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size)
  File "/usr/local/lib/python3.6/site-packages/django/db/models/sql/compiler.py", line 1098, in execute_sql
    cursor = self.connection.cursor()
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/base/base.py", line 256, in cursor
    return self._cursor()
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/base/base.py", line 233, in _cursor
    self.ensure_connection()
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/base/base.py", line 217, in ensure_connection
    self.connect()
  File "/usr/local/lib/python3.6/site-packages/django/db/utils.py", line 89, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/base/base.py", line 217, in ensure_connection
    self.connect()
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/base/base.py", line 195, 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 178, in get_new_connection
    connection = Database.connect(**conn_params)
  File "/usr/local/lib/python3.6/site-packages/psycopg2/__init__.py", line 126, in connect
    conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
django.db.utils.OperationalError: could not connect to server: No such file or directory
        Is the server running locally and accepting
        connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?

Docker-compose:

version: '3'

services:
  road_data_service:
    build:
      context: ./
      dockerfile: ./_docker/backend/local_dev/Dockerfile
    volumes:
      - ./:/server
    network_mode: "host"
    ports:
      - "8326:8000"

Dockerfile:

RUN apt-get update \
  && apt-get install -y binutils libproj-dev gdal-bin \
  && rm -rf /var/lib/apt/lists/*

WORKDIR ./
COPY ./ /server

COPY _docker/backend/local_dev/entrypoint.sh /usr/local/bin/entrypoint.sh
RUN chmod +x /usr/local/bin/entrypoint.sh

ENTRYPOINT ["entrypoint.sh"]
WORKDIR /server/
CMD python3 manage.py runserver 0.0.0.0:8000 && celery -A worker_name \
worker -l info