Dockerize Django + mySql app: (2002, "Can't connect to local MySQL server through socket '/run/mysqld/mysqld.sock' (2)") 错误

Question

I'm trying to dockerize my Django app which uses mySql but I'm facing some problems. It's the first time I use Docker so there may be something basic which I don't understand.

Following some online tutorials, this is my Dockerfile:

FROM python:3.8
ENV PYTHONUNBUFFERED 1
RUN mkdir /code
WORKDIR /code
ADD . /code/
RUN pip install --upgrade pip && pip install -r requirements.txt
RUN pip install mysqlclient
COPY . /code/

And this is my docker-compose:

version: '3'

services: 
  db:
    image: mysql:8
    ports:
      - '3306:3306'
    environment:
       MYSQL_DATABASE: 'database_name'
       MYSQL_USER: 'django'
       MYSQL_PASSWORD: 'django-password'
       MYSQL_ROOT_PASSWORD: 'password'
    volumes:
      - .setup.sql:/docker-entrypoint-initbd.d/setup.sql

  web:
    build: .
    command: python manage.py runserver 0.0.0.0:8000
    volumes:
      - .:/code
    ports:
      - "8000:8000"
    depends_on:
      - db
    links: 
      - db 

settings.py:

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': os.environ.get('MYSQL_DATABASE', 'mysql-db'),
        'USER': os.environ.get('MYSQL_USER', 'mysql-user'),
        'PASSWORD': os.environ.get('MYSQL_PASSWORD', 'mysql-password'),
        'HOST': os.environ.get('MYSQL_DATABASE_HOST', 'db'),
        'PORT': os.environ.get('MYSQL_DATABASE_PORT', 3306),
    }
}

And .env:

MYSQL_DATABASE=database_name
MYSQL_USER=django
MYSQL_PASSWORD=django-password
MYSQL_ROOT_PASSWORD=password
MYSQL_DATABASE_HOST=db
MYSQL_DATABASE_PORT=3306

To dockerize the app, I'm using Docker desktop in Windows 10.

After I run:

docker-compose up -d

I see both containers (db and web) are running, however in the web container I see that django is not able to connect to mySql, as it gives me the error:

django.db.utils.OperationalError: (2002, "Can't connect to local MySQL server through socket '/run/mysqld/mysqld.sock' (2)")

I have seem some similar threads around but they didn't help me understand where the problem is, or how to solve it. Please help me to shed some light on the issue, thank you!

Answer 1

Have you tried starting your db container first?

docker compose up db
docker compose build web
docker compose up

Once the services are built, you will be able to docker compose up without starting db container first as containers will be started in the order of depends_on defined in the docker-compose file.