Docker Compose部署Django项目时PostgreSQL主机名解析失败

问题描述 #

执行docker-compose up启动基于Django、PostgreSQL、Redis、Channels的Docker项目时，出现以下错误：

django.db.utils.OperationalError: could not translate host name "postgres_db" to address: Temporary failure in name resolution

PostgreSQL镜像已创建并可在Docker Desktop中查看，但无法被Django容器识别。

提供的配置文件 #

docker-compose.yml #

version: "3.5"

services:
  redis:
    image: redis:latest
    networks: 
      - redisnet

  postgres_db:
    image: postgres
    volumes:
      - ./data/db:/var/lib/postgresql/data
    environment:
      - POSTGRES_DB=postgres
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=postgres

  django_wsgi:
    container_name: django_wsgi
    build:
      context: .
    command: uwsgi --socket=:9000 --module=core.wsgi:application --py-autoreload=1
    volumes:
      - .:/code
    env_file:
      - .env
    networks: 
      - webnet
      - redisnet
    links:
      - redis
      - postgres_db:postgres_db
    depends_on:
      - postgres_db
  
  django_asgi:
    container_name: django_asgi
    build: .
    # command: python manage.py runserver 0.0.0.0:8002
    command: daphne -b 0.0.0.0 -p 8002  core.asgi:application
    env_file:
      - .env
    volumes:
      - .:/code
    networks: 
      - webnet
      - redisnet
    links:
      - redis
      - postgres_db:postgres_db
    depends_on:
      - postgres_db
      
  nginx:
    image: nginx:1.15.0
    depends_on:
      - django_asgi
      - django_wsgi
    volumes:
      - ./nginx:/etc/nginx/conf.d
      - ./static:/static
    networks:
      - webnet
    ports:
      - "80:80"

networks: 
  webnet:
  redisnet:

Dockerfile #

FROM python:3.8

ENV PYTHONUNBUFFERED 1 
ENV REDIS_HOST "redis" 
RUN mkdir /code 
WORKDIR /code

RUN pip install --upgrade pip 
RUN pip install psycopg2

COPY requirements.txt /code/ 
RUN pip install uwsgi 
RUN apt-get update && apt-get install -y tdsodbc unixodbc-dev

RUN pip install -r requirements.txt 
ADD . /code/

nginx default.conf #

upstream django_wsgi {
  server  django_wsgi:9000;
}

upstream django_asgi {
    server django_asgi:8002;
}

map $http_upgrade $connection_upgrade {
  default upgrade;
    '' close;
}

server {
    listen 80           default_server;
    root                /usr/src/app;
    index               index.html;
    client_max_body_size 60M;

    location / {
      include /etc/nginx/uwsgi_params;
      uwsgi_pass django_wsgi;

      uwsgi_param Host $host;
      uwsgi_param X-Real-IP $remote_addr;
      uwsgi_param X-Forwarded-For $proxy_add_x_forwarded_for;
      uwsgi_param X-Forwarded-Proto $http_x_forwarded_proto;
    }

    location /chat/stream/ {
      proxy_pass http://django_asgi;
      proxy_http_version 1.1;
      proxy_set_header Upgrade $http_upgrade;
      proxy_set_header Connection $connection_upgrade;
      
      proxy_redirect     off;
      proxy_set_header   Host $host;
      proxy_set_header   X-Real-IP $remote_addr;
      proxy_set_header   X-Forwarded-For $proxy_add_x_forwarded_for;
      proxy_set_header   X-Forwarded-Host $server_name;
    }

    location /static {
        alias /static;
    }
}

解决方案 #

1. 修复PostgreSQL的网络配置 #

核心问题：postgres_db服务未加入任何自定义网络，导致Django容器所在的webnet/redisnet无法通过主机名访问它。

修改docker-compose.yml中的postgres_db服务，添加网络配置：

postgres_db:
    image: postgres
    volumes:
      - ./data/db:/var/lib/postgresql/data
    environment:
      - POSTGRES_DB=postgres
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=postgres
    networks:  # 添加这部分
      - webnet
      - redisnet

2. 移除过时的links配置 #

Docker Compose的links是过时特性，在自定义网络中，服务名本身即可作为主机名解析，直接删除django_wsgi和django_asgi中的links字段：

# 从django_wsgi和django_asgi中删除以下内容
links:
  - redis
  - postgres_db:postgres_db

3. 添加PostgreSQL健康检查（可选但推荐） #

depends_on仅保证容器启动顺序，不保证PostgreSQL服务已就绪。添加健康检查确保Django容器在PostgreSQL可用后再启动：

postgres_db:
    image: postgres
    volumes:
      - ./data/db:/var/lib/postgresql/data
    environment:
      - POSTGRES_DB=postgres
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=postgres
    networks:
      - webnet
      - redisnet
    healthcheck:  # 添加健康检查
      test: ["CMD-SHELL", "pg_isready -U postgres"]
      interval: 5s
      timeout: 5s
      retries: 5

同时修改django_wsgi和django_asgi的depends_on，依赖PostgreSQL的健康状态：

depends_on:
  postgres_db:
    condition: service_healthy

4. 验证Django数据库配置 #

确保.env或settings.py中的数据库主机配置为postgres_db：

# settings.py示例
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': 'postgres',
        'USER': 'postgres',
        'PASSWORD': 'postgres',
        'HOST': 'postgres_db',  # 必须和docker-compose中的服务名一致
        'PORT': '5432',
    }
}

操作步骤 #

1. 停止当前运行的容器：docker-compose down
2. 按照上述修改更新配置文件
3. 重新构建并启动容器：docker-compose up --build

内容的提问来源于stack exchange，提问作者turyanazizov