在 Docker 上运行的 Django 中的密码学错误

Question

I'm trying to deploy a web site which has a backend developed in Django. I've set two Docker containers which contain a Django instance and a MySQL instance. I've set also a network between containers in order to create a communication. The problem is that when I start the MySQL container with the parameter MYSQL_ROOT_PASSWORD Django gives me the error below:

return Database.connect(**conn_params)
app    |   File "/usr/local/lib/python3.7/site-packages/pymysql/__init__.py", line 94, in Connect
app    |     return Connection(*args, **kwargs)
app    |   File "/usr/local/lib/python3.7/site-packages/pymysql/connections.py", line 325, in __init__
app    |     self.connect()
app    |   File "/usr/local/lib/python3.7/site-packages/pymysql/connections.py", line 599, in connect
app    |     self._request_authentication()
app    |   File "/usr/local/lib/python3.7/site-packages/pymysql/connections.py", line 882, in _request_authentication
app    |     auth_packet = _auth.caching_sha2_password_auth(self, auth_packet)
app    |   File "/usr/local/lib/python3.7/site-packages/pymysql/_auth.py", line 264, in caching_sha2_password_auth
app    |     data = sha2_rsa_encrypt(conn.password, conn.salt, conn.server_public_key)
app    |   File "/usr/local/lib/python3.7/site-packages/pymysql/_auth.py", line 142, in sha2_rsa_encrypt
app    |     raise RuntimeError("cryptography is required for sha256_password or caching_sha2_password")
app    | RuntimeError: cryptography is required for sha256_password or caching_sha2_password

I've checked that the 3306 port is available on my PC, and yes it is. On the other hand, if I start MySQL container with MYSQL_ALLOW_EMPTY_PASSWORD, and set a blank password in settings.py, it works.

Here there is my settings.py

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'dbname',
        'USER': 'username',
        'PASSWORD': 'userpwd',
        'HOST': 'db',
        'PORT': '3306'
    }
}

Instead, this is my docker-compose.yml file

version: "3"
services:
  app:
    build:
      context: .
    container_name: app
    ports:
      - "8000:8000"
    networks:
      - backend_split
    depends_on:
      - db
    restart: always
    volumes:
      - ./app:/app
    command:
      sh -c "python manage.py runserver 0.0.0.0:8000"
  db:
    image: mysql
    container_name: db
    expose:
      - "3306"
    networks:
      - backend_split
    environment:
      - MYSQL_ROOT_PASSWORD=rootpwd
      - MYSQL_DATABASE=databasename
      - MYSQL_USER=username
      - MYSQL_PASSWORD=userpwd

networks:
  backend_split:

I've been stuck with this error for days.

Thank you in advance.

Answer 1

I've solved this problem on my own. I've opened all kinds of stackOverflow topic about this but nothing. I searched "pip install cryptography" and the tricky was here. So, in Docker which emulate an Alpine environment, the solution is to add these lines of code into your Dockerfile:

RUN apk add gcc
RUN apk add --no-cache libressl-dev musl-dev libffi-dev
RUN pip install --no-cache-dir cryptography==2.1.4
RUN apk del libressl-dev \
        musl-dev \
        libffi-dev

And... it run.

Answer 2

You can solve it by installing this dependency:

1. $ pip install django-cryptographic-fields

2. Add then add "cryptographic_fields" to your INSTALLED_APPS setting like this:

INSTALLED_APPS = (
...
'cryptographic_fields',
)