使用Dockerfile+Github Actions部署至Nginx时端口占用问题排查

我正尝试通过Nginx，使用Dockerfile和Github Actions进行应用部署，却遇到如下错误：

Error starting userland proxy: listen tcp4 0.0.0.0:80: bind: address already in use.

停止服务器上的Nginx后即可部署，但我需要Nginx保持运行状态，请问我哪里操作有误？

我的Dockerfile内容 #

FROM node:20-alpine

WORKDIR /app

COPY package*.json yarn.lock ./

RUN yarn

COPY . .

EXPOSE 8081

CMD [ "yarn", "start" ]

我的Github Actions文件内容 #

name: Deploy to DigitalOcean

on:
  push:
    branches:
      - main

jobs:
  deploy:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout code
        uses: actions/checkout@v4.0.0

      - name: Set up Docker
        uses: docker/setup-buildx-action@v2.10.0

      - name: Login to Docker Hub
        uses: docker/login-action@v2
        with:
          username: ${{ secrets.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}

      - name: Build and push image to Docker Hub
        uses: docker/build-push-action@v4.2.1
        with:
          context: .
          push: true
          tags: ${{ secrets.DOCKERHUB_USERNAME }}/example:${{ github.sha }}
          build-args: |
            NODE_VERSION=20

      - name: Deploy to DigitalOcean Droplet
        uses: appleboy/ssh-action@v1.0.0
        with:
          host: ${{ secrets.DROPLET_IP }}
          username: ${{ secrets.SSH_USERNAME }}
          key: ${{ secrets.SSH_PRIVATE_KEY }}
          port: 22
          script: |
            echo "Pulling Docker image..."
            docker pull ${{ secrets.DOCKERHUB_USERNAME }}/example:${{ github.sha }}

            echo "Stopping and removing existing container (if it exists)..."
            if docker ps -a | grep -q "example-container"; then
              docker stop example-container
              docker rm example-container
            fi

            echo "Starting a new container..."
            docker run -d --name example-container -p 80:8081 ${{ secrets.DOCKERHUB_USERNAME }}/example:${{ github.sha }}

我的Nginx配置文件（/etc/nginx/sites-available/example.com）内容 #

server {
        root /var/www/example.com/html;
        index index.html index.htm index.nginx-debian.html;
        server_name example.com www.example.com;
        location / {
                try_files $uri $uri/ =404;
                proxy_pass http://localhost:8081;
                proxy_set_header Host $host;
                proxy_set_header X-Real-IP $remote_addr;
        }
    listen [::]:443 ssl ipv6only=on; # managed by Certbot
    listen 443 ssl; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem; # managed by Certbot
    include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot
}
server {
    if ($host = www.example.com) {
        return 301 https://$host$request_uri;
    } # managed by Certbot


    if ($host = example.com) {
        return 301 https://$host$request_uri;
    } # managed by Certbot


        listen 80;
        listen [::]:80;

        server_name example.com www.example.com;
    return 404; # managed by Certbot
}

问题原因及解决方案 #

问题原因 #

你在Docker启动命令里把容器的8081端口映射到了主机的80端口（-p 80:8081），但主机上的Nginx已经在监听80端口处理HTTP请求（第二个server块明确配置了listen 80），两者端口冲突导致Docker启动失败。

解决方案 #

方案1：修改Docker端口映射，避开80端口

把Docker的端口映射改成主机的其他空闲端口，比如8080，再调整Nginx的反向代理指向这个新端口：

1. 更新Github Actions里的Docker启动命令：

   docker run -d --name example-container -p 8080:8081 ${{ secrets.DOCKERHUB_USERNAME }}/example:${{ github.sha }}
   

2. 修改Nginx配置中的proxy_pass：

   proxy_pass http://localhost:8080;
   

3. 重启Nginx生效：

   sudo systemctl restart nginx
   

方案2：Docker容器与Nginx同网络，用容器名直接通信（推荐）

这种方式不需要暴露主机端口，安全性更高：

1. 创建一个Docker网络：

   docker network create nginx-network
   

2. 修改Docker启动命令，加入网络并去掉主机端口映射：

   docker run -d --name example-container --network nginx-network ${{ secrets.DOCKERHUB_USERNAME }}/example:${{ github.sha }}
   

3. 修改Nginx配置中的proxy_pass，直接用容器名访问：

   proxy_pass http://example-container:8081;
   

4. 重启Nginx和容器：

   sudo systemctl restart nginx
   docker restart example-container
   

额外注意事项 #

你当前Nginx配置里try_files $uri $uri/ =404;在proxy_pass之前，会优先从本地/var/www/example.com/html读取静态文件。如果你的应用静态文件都在Docker容器里，需要删除root和try_files相关配置，或者调整顺序让代理优先。

内容的提问来源于stack exchange，提问作者kar