Docker Swarm部署nginx+api-service实现负载均衡

背景介绍

api服务开发完毕之后如何快速部署实现负载均衡。如果不是重量级的项目，非常建议使用 Docker Swarm来实现，非常简单高效且稳定。

关于Docker Swarm集群的构建详见我的另一篇博客：Docker Swarm集群搭建

相关文件准备（这里以一个ocr服务为例）

• docker-compose.yml

version: '3.8'

services:
  nginx:
    image: nginx:1.21
    ports:
      - "8080:8088"
    configs:
      - source: nginx.conf
        target: /etc/nginx/nginx.conf
    networks:
      - ocr
    deploy:
      replicas: 1
      restart_policy:
        condition: on-failure
      placement:
        constraints:
          - node.labels.ocr.replica==1

  api-server:
    image: paddleocr:gpu-v3
    hostname: api-server
    networks:
      - ocr
    deploy:
      replicas: 10
      restart_policy:
        condition: on-failure
      placement:
        constraints:
          - node.labels.ocr.replica==1

configs:
  nginx.conf:
    file: ./nginx.conf

networks:
  ocr:
    external: true # 用已经创建好的网络

• nginx.conf

user  nginx;
worker_processes  2;

error_log  /var/log/nginx/error.log;
pid        /var/run/nginx.pid;


events {
    worker_connections  1024;
}


http {
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;

    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';

    access_log  /var/log/nginx/access.log  main;

    sendfile        on;
    #tcp_nopush     on;

    keepalive_timeout  65;

    upstream ocr_servers {
        server api-server:8866;  # Docker 会自动进行 DNS 负载均衡到 API 服务的各个实例
    }

    server {
        listen 8088;
        
        location / {
            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;

            proxy_pass http://ocr_servers;
            proxy_read_timeout 600;  # 可根据实际需求调整

            proxy_redirect off;
            proxy_buffering off;
        }
    }
}

创建专用网络：

docker network create --driver overlay ocr

部署

docker stack deploy -c docker-compose.yml ocr

查看

docker stack ls

NAME      SERVICES
ocr       2

docker service ls

ID             NAME             MODE         REPLICAS   IMAGE              PORTS
c94y6w6r8lok   ocr_api-server   replicated   10/10      paddleocr:gpu-v3   
iliarkza8v68   ocr_nginx        replicated   1/1        nginx:1.21         *:8080->8088/tcp