Build node js app with

docker build -t username:nodejsapp .

Build network

docker network create nginx-app

Run 3 container

docker run --name nodeapp1 -e PORT=8000 --network nginx-app username/nodejsapp:latest  
docker run --name nodeapp2 -e PORT=7000 --network nginx-app username/nodejsapp:latest  
docker run --name nodeapp3 -e PORT=5000 --network nginx-app username/nodejsapp:latest  

Run nginx container

docker run --name nginx-test -p 9000:80 --network nginx-app -v $(pwd)/default.conf:/etc/nginx/nginx.conf nginx

Run curl to test endpoint

// round roubin 
curl localhost:9000/all

// reverse proxy
curl localhost:9000/app
curl localhost:9000/test
curl localhost:9000/appsatu