Traefik代理Mailpit 8025端口返回404问题排查与解决

已配置Traefik作为反向代理，whoami服务和Traefik控制台均可正常访问，但添加Mailpit服务后，通过https://localhost/mailpit访问返回404 page not found，直接访问http://localhost:8025则正常，Traefik控制台也能识别到Mailpit服务地址，容器内也可正常访问该地址。

现有Traefik配置 #

docker-compose.yaml #

services:
  traefik:
    image: traefik:latest
    container_name: traefik
    ports:
      - "80:80"
      - "443:443"
    volumes:
      - ./htpasswd:/htpasswd
      - ./traefik.yaml:/etc/traefik/traefik.yaml
      - /var/run/docker.sock:/var/run/docker.sock
    labels:
      - "traefik.http.routers.dashboard.rule=Host(`localhost`) && (PathPrefix(`/api`) || PathPrefix(`/dashboard`))"
      - "traefik.http.routers.dashboard.service=api@internal"
      - "traefik.http.routers.dashboard.tls=true"
      - "traefik.http.routers.dashboard.middlewares=auth"
      - "traefik.http.middlewares.auth.basicauth.usersfile=/htpasswd"
    networks:
      - traefik

  whoami:
    image: traefik/whoami
    labels:
      - "traefik.http.routers.whoami.rule=Host(`localhost`) && PathPrefix(`/whoami`)"
      - "traefik.http.routers.whoami.tls=true"
    networks:
      - traefik

networks:
  traefik:
    external: true

traefik.yaml（静态配置） #

api:
  dashboard: true

entrypoints:
  web:
    address: ":80"
  websecure:
    address: ":443"

log:
  level: TRACE

metrics:
  addInternals: true

providers:
  docker:
    endpoint: "unix:///var/run/docker.sock"

验证现有配置正常：
执行以下命令可正常返回whoami结果：

$ curl -sk https://localhost/whoami | head 
Hostname: ea1b0e62d773
IP: 127.0.0.1
IP: ::1
IP: 172.19.0.3
RemoteAddr: 172.19.0.2:37404
GET /whoami HTTP/1.1
Host: localhost
User-Agent: curl/8.9.1
Accept: */*
Accept-Encoding: gzip

同时可通过https://localhost/dashboard/访问Traefik控制台。

Mailpit初始配置及404问题 #

添加的Mailpit服务docker-compose.yml：

services:
  mailpit:
    image: axllent/mailpit
    container_name: mailpit
    restart: unless-stopped
    volumes:
      - mailpit-data:/data
    ports:
      - 8025:8025
      - 1025:1025
    environment:
      MP_MAX_MESSAGES: 5000
      MP_DATABASE: /data/mailpit.db
      MP_SMTP_AUTH_ACCEPT_ANY: 1
      MP_SMTP_AUTH_ALLOW_INSECURE: 1
    labels:
      - "traefik.http.routers.mailpit.rule=Host(`localhost`) && PathPrefix(`/mailpit`)"
      - "traefik.http.routers.mailpit.tls=true"
      - "traefik.http.routers.mailpit.service=mailpit"
      - "traefik.http.services.mailpit.loadbalancer.server.port=8025"
    networks:
      - traefik

volumes:
  mailpit-data:

networks:
  traefik:
    external: true

访问测试返回404：

$ curl -sk https://localhost/mailpit | head
404 page not found

但Mailpit本身运行正常：

• 直接访问http://localhost:8025可打开控制台
• Traefik控制台显示Mailpit服务地址为http://172.19.0.4:8025
• 在Traefik容器内部可正常访问该地址：

$ docker exec -it traefik wget -O - http://172.19.0.4:8025 | head
Connecting to 172.19.0.4:8025 (172.19.0.4:8025)
writing to stdout
<!DOCTYPE html>
<html lang="en" class="h-100">

<head>
        <meta charset="utf-8">
        <meta name="viewport" content="width=device-width,initial-scale=1.0">
        <meta name="referrer" content="no-referrer">
        <meta name="robots" content="noindex, nofollow, noarchive">

问题原因 #

Traefik默认会将请求的完整路径原样转发给后端服务，当访问https://localhost/mailpit时，实际转发给Mailpit的请求路径是/mailpit，但Mailpit的服务根路径是/，并不存在/mailpit这个路由，因此返回404。若使用路径剥离中间件，可能会引发Mailpit内部静态资源加载路径错误等其他问题。

解决方案：使用专属Host #

修改Mailpit的docker-compose.yml，移除路径匹配规则，改用专属Host（如mailpit.localhost）：

services:
  mailpit:
    image: axllent/mailpit
    restart: unless-stopped
    volumes:
      - mailpit-data:/data
    ports:
      - 8025:8025
      - 1025:1025
    environment:
      MP_MAX_MESSAGES: 5000
      MP_DATABASE: /data/mailpit.db
      MP_SMTP_AUTH_ACCEPT_ANY: 1
      MP_SMTP_AUTH_ALLOW_INSECURE: 1
    labels:
      - "traefik.http.routers.mailpit.rule=Host(`mailpit.localhost`)"
      - "traefik.http.routers.mailpit.tls=true"
      - "traefik.http.routers.mailpit.service=mailpit"
      - "traefik.http.services.mailpit.loadbalancer.server.port=8025"
    networks:
      - traefik

volumes:
  mailpit-data:

networks:
  traefik:
    external: true

修改后，通过https://mailpit.localhost即可正常访问Mailpit服务。

内容的提问来源于stack exchange，提问作者dyle