Docker&Celery - ERROR: Pidfile (celerybeat.pid) already exists

Question

Application consists of: - Django - Redis - Celery - Docker - Postgres

Before merging the project into docker, everything was working smooth and fine, but once it has been moved into containers, something wrong started to happen. At first it starts perfectly fine, but after a while I do receive folowing error:

celery-beat_1  | ERROR: Pidfile (celerybeat.pid) already exists.

I've been struggling with it for a while, but right now I literally give up. I've no idea of what is wrong with it.

Dockerfile:

FROM python:3.7

ENV PYTHONUNBUFFERED 1
RUN mkdir -p /opt/services/djangoapp/src


COPY /scripts/startup/entrypoint.sh entrypoint.sh
RUN chmod +x /entrypoint.sh
ENTRYPOINT ["/entrypoint.sh"]

COPY Pipfile Pipfile.lock /opt/services/djangoapp/src/
WORKDIR /opt/services/djangoapp/src
RUN pip install pipenv && pipenv install --system

COPY . /opt/services/djangoapp/src

RUN find . -type f -name "celerybeat.pid" -exec rm -f {} \;

RUN sed -i "s|django.core.urlresolvers|django.urls |g" /usr/local/lib/python3.7/site-packages/vanilla/views.py
RUN cp /usr/local/lib/python3.7/site-packages/celery/backends/async.py /usr/local/lib/python3.7/site-packages/celery/backends/asynchronous.py
RUN rm /usr/local/lib/python3.7/site-packages/celery/backends/async.py
RUN sed -i "s|async|asynchronous|g" /usr/local/lib/python3.7/site-packages/celery/backends/redis.py
RUN sed -i "s|async|asynchronous|g" /usr/local/lib/python3.7/site-packages/celery/backends/rpc.py

RUN cd app && python manage.py collectstatic --no-input



EXPOSE 8000
CMD ["gunicorn", "-c", "config/gunicorn/conf.py", "--bind", ":8000", "--chdir", "app", "example.wsgi:application", "--reload"]

docker-compose.yml:

version: '3'

services:

  djangoapp:
    build: .
    volumes:
      - .:/opt/services/djangoapp/src
      - static_volume:/opt/services/djangoapp/static  # <-- bind the static volume
      - media_volume:/opt/services/djangoapp/media  # <-- bind the media volume
      - static_local_volume:/opt/services/djangoapp/src/app/static
      - media_local_volume:/opt/services/djangoapp/src/app/media
      - .:/code
    restart: always
    networks:
      - nginx_network
      - database1_network # comment when testing
      # - test_database1_network # uncomment when testing
      - redis_network
    depends_on:
      - database1 # comment when testing
      # - test_database1 # uncomment when testing
      - migration
      - redis

  # base redis server
  redis:
    image: "redis:alpine"
    restart: always
    ports: 
      - "6379:6379"
    networks:
      - redis_network
    volumes:
      - redis_data:/data

  # celery worker
  celery:
    build: .
    command: >
      bash -c "cd app && celery -A example worker --without-gossip --without-mingle --without-heartbeat -Ofair"
    volumes:
      - .:/opt/services/djangoapp/src
      - static_volume:/opt/services/djangoapp/static  # <-- bind the static volume
      - media_volume:/opt/services/djangoapp/media  # <-- bind the media volume    
      - static_local_volume:/opt/services/djangoapp/src/app/static
      - media_local_volume:/opt/services/djangoapp/src/app/media
    networks:
      - redis_network
      - database1_network # comment when testing
      # - test_database1_network # uncomment when testing
    restart: always
    depends_on:
      - database1 # comment when testing
      # - test_database1 # uncomment when testing
      - redis
    links:
      - redis

  celery-beat:
    build: .
    command: >
      bash -c "cd app && celery -A example beat"
    volumes:
      - .:/opt/services/djangoapp/src
      - static_volume:/opt/services/djangoapp/static  # <-- bind the static volume
      - media_volume:/opt/services/djangoapp/media  # <-- bind the media volume
      - static_local_volume:/opt/services/djangoapp/src/app/static
      - media_local_volume:/opt/services/djangoapp/src/app/media
    networks:
      - redis_network
      - database1_network # comment when testing
      # - test_database1_network # uncomment when testing
    restart: always
    depends_on:
      - database1 # comment when testing
      # - test_database1 # uncomment when testing
      - redis
    links:
      - redis

  # migrations needed for proper db functioning
  migration:
    build: .
    command: >
      bash -c "cd app && python3 manage.py makemigrations && python3 manage.py migrate"
    depends_on:
      - database1 # comment when testing
      # - test_database1 # uncomment when testing
    networks:
     - database1_network # comment when testing
     # - test_database1_network # uncomment when testing

  # reverse proxy container (nginx)
  nginx:
    image: nginx:1.13
    ports:
      - 80:80
    volumes:
      - ./config/nginx/conf.d:/etc/nginx/conf.d
      - static_volume:/opt/services/djangoapp/static  # <-- bind the static volume
      - media_volume:/opt/services/djangoapp/media  # <-- bind the media volume
      - static_local_volume:/opt/services/djangoapp/src/app/static
      - media_local_volume:/opt/services/djangoapp/src/app/media 
    restart: always
    depends_on:
      - djangoapp
    networks:
      - nginx_network

  database1: # comment when testing
    image: postgres:10 # comment when testing
    env_file: # comment when testing
      - config/db/database1_env # comment when testing
    networks: # comment when testing
      - database1_network # comment when testing
    volumes: # comment when testing
      - database1_volume:/var/lib/postgresql/data # comment when testing

  # test_database1: # uncomment when testing
    # image: postgres:10 # uncomment when testing
    # env_file: # uncomment when testing
      # - config/db/test_database1_env # uncomment when testing
    # networks: # uncomment when testing
      # - test_database1_network # uncomment when testing
    # volumes: # uncomment when testing
      # - test_database1_volume:/var/lib/postgresql/data # uncomment when testing


networks:
  nginx_network:
    driver: bridge
  database1_network: # comment when testing
    driver: bridge # comment when testing
  # test_database1_network: # uncomment when testing
    # driver: bridge # uncomment when testing
  redis_network:
    driver: bridge
volumes:
  database1_volume: # comment when testing
  # test_database1_volume: # uncomment when testing
  static_volume:  # <-- declare the static volume
  media_volume:  # <-- declare the media volume
  static_local_volume:
  media_local_volume:
  redis_data:

Please, ignore "test_database1_volume" as it exists only for test purposes.

Answer 1

Another solution (taken from https://stackoverflow.com/a/17674248/39296) is to use --pidfile= (with no path) to not create a pidfile at all. Same effect as Siyu's answer above.