Nginx反向代理无法访问Prometheus等Docker容器问题排查

一、修改Docker网络的Internal和Attachable属性 #

1. 针对已创建的现有网络 #

直接用docker network update命令修改：

# 开启Attachable属性，允许外部容器连接到该网络
docker network update --attachable=true <你的网络名称>
# 关闭Internal属性，允许网络内容器与外部通信
docker network update --internal=false <你的网络名称>

2. 在Docker Compose中提前定义网络参数 #

在compose文件的networks块里直接配置：

networks:
  monitoring-net:
    driver: bridge
    internal: false  # 允许网络与外部互通
    attachable: true # 允许外部容器接入该网络

二、Nginx反向代理404问题核心修复 #

404的本质是：当你访问http://你的域名/prometheus时，Nginx默认把请求转发给Prometheus容器的/prometheus路径，但Prometheus/Grafana默认根路径是/，自然找不到对应资源。以下两种方案任选：

方案1：Nginx配置路径重写 #

在Nginx的server块里添加如下location规则：

server {
    listen 80;
    server_name localhost;

    # 保留你正常的根路径配置
    location / {
        root /usr/share/nginx/html;
        index index.html index.htm;
    }

    # Prometheus反向代理
    location /prometheus/ {
        # 重写路径，去掉/prometheus前缀后转发到Prometheus的根路径
        rewrite ^/prometheus/(.*)$ /$1 break;
        proxy_pass http://prometheus:9090/;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }

    # Grafana反向代理
    location /grafana/ {
        rewrite ^/grafana/(.*)$ /$1 break;
        proxy_pass http://grafana:3000/;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        # Grafana需要额外头部防止跳转错误
        proxy_set_header X-Forwarded-Proto $scheme;
    }
}

注意：访问时要带末尾斜杠，比如http://localhost/prometheus/，若不想带斜杠，可将location改为location /prometheus并调整rewrite规则。

方案2：修改Prometheus/Grafana的外部URL参数（推荐） #

通过启动参数让服务自身适配子路径，避免Nginx复杂重写：

Prometheus配置（在Docker Compose的services块中）

prometheus:
    image: prom/prometheus:latest
    command:
      --config.file=/etc/prometheus/prometheus.yml
      --web.external-url=http://localhost/prometheus  # 指定外部访问的URL前缀
      --web.route-prefix=/  # 保持内部路由前缀为/
    volumes:
      - ./prometheus/config:/etc/prometheus
      - prometheus-data:/prometheus
    networks:
      - monitoring-net

Grafana配置（在Docker Compose的services块中）

grafana:
    image: grafana/grafana:latest
    environment:
      - GF_SERVER_ROOT_URL=http://localhost/grafana  # 指定外部访问根URL
      - GF_SERVER_SERVE_FROM_SUB_PATH=true  # 开启子路径服务模式
      - GF_SECURITY_ADMIN_PASSWORD=admin  # 可自定义初始密码
    volumes:
      - grafana-data:/var/lib/grafana
    networks:
      - monitoring-net

对应的Nginx配置可简化为：

location /prometheus/ {
    proxy_pass http://prometheus:9090/prometheus/;
    proxy_set_header Host $host;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}

location /grafana/ {
    proxy_pass http://grafana:3000/grafana/;
    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-Proto $scheme;
}

三、完整Docker Compose示例 #

整合所有配置的完整文件：

version: '3.8'

services:
  nginx:
    image: nginx:alpine
    ports:
      - "80:80"
    volumes:
      - ./nginx/conf.d:/etc/nginx/conf.d  # 挂载你的Nginx配置文件目录
      - ./nginx/html:/usr/share/nginx/html
    networks:
      - monitoring-net
    depends_on:
      - prometheus
      - grafana

  prometheus:
    image: prom/prometheus:latest
    command:
      --config.file=/etc/prometheus/prometheus.yml
      --web.external-url=http://localhost/prometheus
      --web.route-prefix=/
    volumes:
      - ./prometheus/prometheus.yml:/etc/prometheus/prometheus.yml
      - prometheus-data:/prometheus
    networks:
      - monitoring-net

  grafana:
    image: grafana/grafana:latest
    environment:
      - GF_SERVER_ROOT_URL=http://localhost/grafana
      - GF_SERVER_SERVE_FROM_SUB_PATH=true
      - GF_SECURITY_ADMIN_PASSWORD=admin
    volumes:
      - grafana-data:/var/lib/grafana
    networks:
      - monitoring-net

volumes:
  prometheus-data:
  grafana-data:

networks:
  monitoring-net:
    driver: bridge
    internal: false
    attachable: true

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