Docker Compose无法连接PostgreSQL容器问题求助

问题场景 #

我的docker-compose.yaml配置如下：

version: '3.3'

services:
  django:
    build: ./project # Dockerfile路径
    command: sh -c " 
      sleep 3 && gunicorn --bind 0.0.0.0:8000 core_app.wsgi"
    volumes:
      - ./project:/project
      - ./project/static:/project/static
      - ./project/media:/project/media
      - ./project/logs:/project/logs
    expose:
      - 8000
    env_file:
      - ./.env
    depends_on:
      - db

  
  db:
    image: postgres:13-alpine
    volumes:
      - pg_data:/var/lib/postgresql/data/
    expose: 
      - 5432
    ports:
      - "5433:5432"
    env_file:
      - .env
    environment:
      - POSTGRES_USER=postgresuser
      - POSTGRES_PASSWORD=post222
      - POSTGRES_DB=yandex_parser_db

无法连接到db容器内的PostgreSQL数据库，操作及错误如下：

执行docker-compose ps输出：

sudo docker-compose ps
               Name                              Command               State            Ports         
------------------------------------------------------------------------------------------------------
app-content-protect_db_1              docker-entrypoint.sh postgres    Up       0.0.0.0:5433->5432/tcp
app-content-protect_django_1          sh -c  sleep 3 && gunicorn ...   Exit 3         

进入db容器执行连接命令：

sudo docker exec -ti app-content-protect_db_1 bash
e21385ac10e4:/# psql -h db -U postgresuser
Password for user postgresuser: 
psql: error: FATAL:  password authentication failed for user "postgresuser"

启动docker-compose时的日志错误：

db_1             | 2024-11-19 17:59:52.314 UTC [32] FATAL:  password authentication failed for user "postgresuser"
db_1             | 2024-11-19 17:59:52.314 UTC [32] DETAIL:  Role "postgresuser" does not exist.
db_1             |  Connection matched pg_hba.conf line 99: "host all all all md5"
django_1         | [2024-11-19 20:59:52 +0300] [9] [ERROR] Exception in worker process
django_1         | Traceback (most recent call last):
django_1         |   File "/usr/local/lib/python3.9/site-packages/django/db/backends/base/base.py", line 244, in ensure_connection
django_1         |     self.connect()
django_1         |   File "/usr/local/lib/python3.9/site-packages/django/utils/asyncio.py", line 26, in inner
django_1         |     return func(*args, **kwargs)
django_1         |   File "/usr/local/lib/python3.9/site-packages/django/db/backends/base/base.py", line 225, in connect
django_1         |     self.connection = self.get_new_connection(conn_params)
django_1         |   File "/usr/local/lib/python3.9/site-packages/django/utils/asyncio.py", line 26, in inner
django_1         |     return func(*args, **kwargs)
django_1         |   File "/usr/local/lib/python3.9/site-packages/django/db/backends/postgresql/base.py", line 203, in get_new_connection
django_1         |     connection = Database.connect(**conn_params)
django_1         |   File "/usr/local/lib/python3.9/site-packages/psycopg2/__init__.py", line 122, in connect
django_1         |     conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
django_1         | psycopg2.OperationalError: FATAL:  password authentication failed for user "postgresuser"

解决步骤 #

1. 清理旧数据卷 #

PostgreSQL首次启动时会根据环境变量创建用户、数据库，一旦数据卷pg_data生成，后续修改环境变量不会生效。必须先删除旧数据卷：

# 停止并删除容器
docker-compose down
# 删除pg_data数据卷
docker volume rm app-content-protect_pg_data

2. 解决环境变量冲突 #

db服务同时配置了env_file和environment，如果.env文件里存在POSTGRES_USER、POSTGRES_PASSWORD、POSTGRES_DB，会覆盖environment中的设置。二选一即可：

• 方案一：删除env_file行，仅保留environment配置；
• 方案二：把PostgreSQL相关变量移到.env文件，删除environment块，确保变量值统一。

3. 重新启动容器 #

清理数据卷并调整配置后，重新构建启动：

docker-compose up -d --build

4. 验证连接 #

进入db容器，用正确参数连接：

docker exec -ti app-content-protect_db_1 psql -U postgresuser -d yandex_parser_db

输入密码post222即可成功连接。

5. 同步Django配置 #

确保Django的settings.py数据库配置与容器变量一致：

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': 'yandex_parser_db',
        'USER': 'postgresuser',
        'PASSWORD': 'post222',
        'HOST': 'db',
        'PORT': 5432,
    }
}

如果使用.env文件，建议从环境变量读取配置：

import os
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': os.getenv('POSTGRES_DB'),
        'USER': os.getenv('POSTGRES_USER'),
        'PASSWORD': os.getenv('POSTGRES_PASSWORD'),
        'HOST': os.getenv('DB_HOST', 'db'),
        'PORT': os.getenv('DB_PORT', 5432),
    }
}

内容的提问来源于stack exchange，提问作者mascai