Docker容器中Nginx+PHP-FPM出现502错误，请求排查配置问题

问题场景 #

尝试在php:8.2-fpm Docker容器中安装Nginx，配置完成后通过浏览器访问出现502错误，Nginx日志提示连接127.0.0.1:9000被拒绝，但控制台可正常执行PHP文件。

用户提供的配置文件 #

Dockerfile #

FROM php:8.2-fpm

# Instala Nginx y herramientas necesarias
RUN apt-get update && apt-get install -y nginx wget

# Instala Xdebug
RUN pecl install xdebug && docker-php-ext-enable xdebug

# Configura Nginx
COPY ./nginx/default.conf /etc/nginx/conf.d/default.conf

# Inicia PHP-FPM y Nginx
CMD ["nginx", "-g", "daemon off;"]

docker-compose.yml #

version: '3'
services:
  php-fpm:
    build: .
    volumes:
      - ./src:/var/www/html
    ports:
      - 9000:9000
      - 80:80

default.conf #

server {
    listen 80;
    server_name localhost;

    location / {
        root /var/www/html;
        index index.php;
    }

    location ~ \.php$ {
        fastcgi_pass localhost:9000;
        fastcgi_index index.php;
        include fastcgi_params;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
    }
}

Nginx错误日志 #

2024/02/27 17:50:18 [error] 11#11: *19 connect() failed (111: Connection refused) while connecting to upstream, client: 172.22.0.1, server: localhost, request: "GET / HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "localhost"

核心问题原因 #

容器启动命令仅运行了Nginx，未启动PHP-FPM进程：

• php:8.2-fpm镜像默认启动命令是启动PHP-FPM，但Dockerfile中用CMD ["nginx", "-g", "daemon off;"]覆盖了默认命令，导致容器内只有Nginx在运行，PHP-FPM未启动，Nginx无法连接到9000端口处理PHP请求。

解决步骤 #

方法一：用Supervisord管理多进程 #

通过Supervisord同时启动PHP-FPM和Nginx，这是容器内运行多进程的标准方案。

1. 修改Dockerfile

FROM php:8.2-fpm

# 安装依赖与Supervisord
RUN apt-get update && apt-get install -y nginx wget supervisor

# 安装Xdebug
RUN pecl install xdebug && docker-php-ext-enable xdebug

# 复制Nginx配置
COPY ./nginx/default.conf /etc/nginx/conf.d/default.conf

# 配置Supervisord
RUN echo "[supervisord]" > /etc/supervisor/conf.d/supervisord.conf && \
    echo "nodaemon=true" >> /etc/supervisor/conf.d/supervisord.conf && \
    echo "" >> /etc/supervisor/conf.d/supervisord.conf && \
    echo "[program:php-fpm]" >> /etc/supervisor/conf.d/supervisord.conf && \
    echo "command=php-fpm" >> /etc/supervisor/conf.d/supervisord.conf && \
    echo "autostart=true" >> /etc/supervisor/conf.d/supervisord.conf && \
    echo "autorestart=true" >> /etc/supervisor/conf.d/supervisord.conf && \
    echo "" >> /etc/supervisor/conf.d/supervisord.conf && \
    echo "[program:nginx]" >> /etc/supervisor/conf.d/supervisord.conf && \
    echo "command=nginx -g 'daemon off;'" >> /etc/supervisor/conf.d/supervisord.conf && \
    echo "autostart=true" >> /etc/supervisor/conf.d/supervisord.conf && \
    echo "autorestart=true" >> /etc/supervisor/conf.d/supervisord.conf

# 启动Supervisord
CMD ["supervisord"]

2. 重建并启动容器

docker-compose down && docker-compose build && docker-compose up -d

方法二：用Shell脚本启动多进程 #

如果不想依赖Supervisord，可通过自定义脚本启动两个进程。

1. 创建启动脚本start.sh（项目根目录）

#!/bin/bash
# 后台启动PHP-FPM
php-fpm &
# 前台运行Nginx（保持容器存活）
nginx -g "daemon off;"

添加执行权限：

chmod +x start.sh

2. 修改Dockerfile

FROM php:8.2-fpm

# 安装依赖
RUN apt-get update && apt-get install -y nginx wget

# 安装Xdebug
RUN pecl install xdebug && docker-php-ext-enable xdebug

# 复制Nginx配置
COPY ./nginx/default.conf /etc/nginx/conf.d/default.conf

# 复制启动脚本
COPY start.sh /usr/local/bin/start.sh
RUN chmod +x /usr/local/bin/start.sh

# 执行启动脚本
CMD ["start.sh"]

3. 重建并启动容器

docker-compose down && docker-compose build && docker-compose up -d

额外验证步骤 #

1. 确认./src目录下存在index.php测试文件，例如：

<?php phpinfo(); ?>

2. 进入容器检查PHP-FPM状态：

docker exec -it [容器ID/名称] netstat -tulpn | grep 9000

应能看到php-fpm进程监听127.0.0.1:9000。

内容的提问来源于stack exchange，提问作者user3447780