Nginx代理无法转发至Docker容器？技术求助

环境配置 #

Docker网络创建命令 #

docker network create my-network

Backend的docker-compose.yml #

version: '3'
services:
  my-backend:
    image: my-backend
    ports:
      - "8080:8080"
    networks:
      - my-network
networks:
  my-network:
    driver: bridge
    external: true

Frontend的docker-compose.yml #

version: '3'
services:
  my-frontend:
    image: my-frontend
    ports:
      - "4200:80"
    networks:
      - my-network
networks:
  my-network:
    driver: bridge
    external: true

问题现象 #

• Frontend容器内通过curl http://my-backend:8080/somepath可正常访问后端接口
• 浏览器访问http://localhost:4200能正常打开前端应用，http://localhost:4200/example转发正常
• 访问http://localhost:4200/backend/deployment-info时Nginx返回404，但直接访问http://localhost:8080/deployment-info正常

补充配置与调试信息 #

修改Nginx配置，添加反向代理规则：

location /backend {
  resolver 127.0.0.11; # 同时在http和server段添加了该行
  set $backend http://my-backend:8080;
  proxy_pass $backend;
}

使用nginx-debug调试，关键日志显示：

my-frontend_1  | 2022/11/08 12:56:02 [debug] 30#30: *5 http request line: "GET /backend/deployment-info HTTP/1.1"
my-frontend_1  | 2022/11/08 12:56:02 [debug] 30#30: *5 http uri: "/backend/deployment-info"
my-frontend_1  | 2022/11/08 12:56:02 [debug] 30#30: *5 test location: "backend"
my-frontend_1  | 2022/11/08 12:56:02 [debug] 30#30: *5 using configuration "/backend"
my-frontend_1  | 2022/11/08 12:56:02 [debug] 30#30: *5 http script value: "http://my-backend:8080"
my-frontend_1  | 2022/11/08 12:56:02 [debug] 30#30: *5 http script set $backend
my-frontend_1  | 2022/11/08 12:56:02 [debug] 30#30: *5 http upstream resolve: "/backend/deployment-info?"
my-frontend_1  | 2022/11/08 12:56:02 [debug] 30#30: *5 name was resolved to 172.19.0.2
my-frontend_1  | 2022/11/08 12:56:02 [debug] 30#30: *5 connect to 172.19.0.2:8080, fd:13 #7
my-frontend_1  | 2022/11/08 12:56:02 [debug] 30#30: *5 http proxy status 404 "404 Not Found"

已验证curl 172.19.0.2:8080/deployment-info可正常访问后端接口。

问题原因与解决方案 #

从日志可见，Nginx把请求/backend/deployment-info原封不动转发给了后端，但后端实际接口路径是/deployment-info，而非/backend/deployment-info，因此后端返回404。

调整Nginx配置，去掉转发路径中的/backend前缀，有两种写法可选：

1. 带变量的写法（保留resolver配置）：

location /backend {
  resolver 127.0.0.11;
  set $backend http://my-backend:8080;
  rewrite ^/backend(.*)$ $1 break;
  proxy_pass $backend;
}

2. 更简洁的写法（利用路径自动替换）：

location /backend/ {
  resolver 127.0.0.11;
  proxy_pass http://my-backend:8080/;
}

注意location和proxy_pass末尾的斜杠，它们会自动把请求中的/backend/替换为/，转发后的路径变为/deployment-info，后端即可正确处理。

内容的提问来源于stack exchange，提问作者Searles