Docker部署Django应用（Nginx+Gunicorn）数据库连接失败求助

问题描述 #

我是业余开发者，平时靠搜索能解决大部分问题，但Docker配置的多样性把我搞懵了。现在尝试把Django应用用Nginx和Gunicorn容器化部署到VPS，docker-compose里配置了db、django_gunicorn、nginx三个服务。db和nginx容器启动正常，但django_gunicorn运行时无法连接数据库，报错：

django.db.utils.OperationalError: (2003, "Can't connect to MySQL server on 'db' ([Errno 111] Connection refused)")

已确认容器内数据库运行正常，Django settings.py里的凭据与数据库一致，HOST设为docker-compose中的db服务，端口3306。以下是我的文件结构及配置代码：

文件结构 #

whatsthefit
- .venv
- conf
  - __pycache__
  - gunicorn_config.py
- nginx
  - default.conf
  - Dockerfile
- whatzthefit
  - App1
  - App2
- manage.py
- requirements.txt
- .dockerignore
- .env
- .gitignore
- docker-compose.yml
- Dockerfile
- entrypoint.sh

配置文件 #

docker-compose.yml #

version: "3.7"

services:
  db:
    image: mysql:oraclelinux8
    restart: always
    environment:
      - MYSQL_ROOT_PASSWORD=${MYSQL_ROOT_PASSWORD}
      - MYSQL_DATABASE=${DB_NAME}
      - MYSQL_USER=${DB_USER}
      - MYSQL_PASSWORD=${DB_PASS}
    ports:
      - "3306:3306"
    expose:
      - "3306"
    volumes:
      - data:/var/lib/mysql
    healthcheck:
      test: ["CMD", "mysqladmin", "ping", "-h", "localhost", "-u", "${DB_USER}", "-p${MYSQL_ROOT_PASSWORD}"]
      interval: 10s
      retries: 3

  django_gunicorn:
    volumes:
      - static:/static
    env_file:
      - /home/ynot/fitweb/whatzthefit/.env
    build:
      context: .
    ports:
      - "8080:8080"
    depends_on:
      - db

  nginx:
    build: ./nginx
    volumes:
      - static:/static
      - media:/media
    ports:
      - "84:84"
    depends_on:
      - django_gunicorn

volumes:
  static:
  data:
  media:

NGINX default.conf #

upstream django {
    server django_gunicorn:8080;
}

server {
    listen 84;

    location / {
        proxy_pass http://django;
    }

    location /static/ {
        alias /static;
    }

    location /media/{
        alias /media;
    }
}

nginx Dockerfile #

FROM nginx:1.25.4-alpine-slim

COPY ./default.conf /etc/nginx/conf.d/default.conf

主Dockerfile #

FROM nginx:1.25.4-alpine-slim

# replace the nginx default conf by the one we made in this folder
COPY ./default.conf /etc/nginx/conf.d/default.conf

entrypoint.sh #

#!/bin/sh

python manage.py migrate --noinput
python manage.py collectstatic --noinput

gunicorn fitweb.wsgi:application --bind 0.0.0.0:8000

gunicorn_config.py #

import os

command = "/home/ynot/fitweb/whatzthefit/.venv/bin/gunicorn"
pythonpath = "/home/ynot/fitweb/whatzthefit/whatzthefit"
bind = "0.0.0.0:8000"
workers = 3

核心问题与修复方案 #

1. 主Dockerfile镜像错误 #

django_gunicorn服务需要Python环境运行Django和Gunicorn，但你当前的主Dockerfile用的是Nginx镜像，完全不符合需求。替换为Python基础镜像：

FROM python:3.11-slim

WORKDIR /app

# 安装依赖
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt

# 复制项目文件
COPY . .

# 赋予entrypoint执行权限
RUN chmod +x entrypoint.sh

ENTRYPOINT ["./entrypoint.sh"]

2. 服务启动顺序与健康检查依赖 #

depends_on仅保证容器启动顺序，不保证数据库服务就绪。修改django_gunicorn服务配置，等待db健康检查通过后再启动：

django_gunicorn:
    volumes:
      - static:/static
    env_file:
      - /home/ynot/fitweb/whatzthefit/.env
    build:
      context: .
    ports:
      - "8080:8000"  # 容器内Gunicorn绑定8000，映射到主机8080，与Nginx配置对应
    depends_on:
      db:
        condition: service_healthy  # 等待数据库服务就绪

同时修正db服务的健康检查命令，用普通用户密码而非root密码：

healthcheck:
  test: ["CMD", "mysqladmin", "ping", "-h", "localhost", "-u", "${DB_USER}", "-p${DB_PASS}"]
  interval: 10s
  retries: 3

3. 端口映射与Gunicorn配置不匹配 #

entrypoint.sh中Gunicorn绑定的是8000端口，但docker-compose里django_gunicorn的端口映射是8080:8080，导致端口不通。已在上一步修正映射为8080:8000，同时修正entrypoint.sh中的WSGI模块路径（你的项目根模块是whatzthefit，不是fitweb）：

#!/bin/sh

python manage.py migrate --noinput
python manage.py collectstatic --noinput

# 修正WSGI模块路径，直接指定参数无需依赖本地配置文件
gunicorn whatzthefit.wsgi:application --bind 0.0.0.0:8000 --workers 3

4. Gunicorn配置文件路径无效 #

容器内不存在你本地的.venv路径，gunicorn_config.py中的路径完全无效，直接在entrypoint.sh中指定启动参数即可，无需依赖该配置文件。

验证步骤 #

1. 清理旧容器与数据卷：docker-compose down -v
2. 重新构建镜像：docker-compose build
3. 启动服务：docker-compose up -d
4. 查看django_gunicorn日志确认修复：docker-compose logs django_gunicorn

内容的提问来源于stack exchange，提问作者Tony