version: '3'
services:
  tomcat1:
    image: tomcat
    container_name: tomcat1
    ports:
      - 9090:8080

  tomcat2:
    image: tomcat
    container_name: tomcat2
    ports:
      - 9091:8080

docker-compose up -d

docker ps

CONTAINER ID  IMAGE    COMMAND    CREATED    STATUS    PORTS     NAMES
271dd3610d1d  tomcat    "catalina.sh run" 58 minutes ago  Up 58 minutes  0.0.0.0:9091->8080/tcp tomcat2
fa19d20f0022  tomcat    "catalina.sh run" 58 minutes ago  Up 58 minutes  0.0.0.0:9090->8080/tcp tomcat1

docker exec -it fa19d20f0022 bash

echo "9090"  webapps/ROOT/index.jsp

version: '3.1'
services:
  nginx:
    restart: always
    image: nginx
    container_name: nginx
    ports:
      - 81:80
    volumes:
      - ./conf/nginx.conf:/etc/nginx/nginx.conf

user nginx;
worker_processes 1;

events {
 worker_connections 1024;
}

http {
 upstream myapp1 {
  server [服务器ip]:9090 weight=10;
  server [服务器ip]:9091 weight=10;
 }
 server {

  listen 80;
  server_name [服务器ip];
  location / {
   proxy_pass http://myapp1;
  }
 }
}

docker-compose up -d