Http request from one application to another via Nginx

Question

I have just started with Nginx, kindly bear with me.

My scenario is one application is sending Http request to another ( both deployed on Jboss). I want to pass this request via Nginx.

The request url in normal case ( where it is working as expected) :

https://localhost:8443/AppName/serviceName/methodName

I am using Nginx as docker container and the entry in the compose file looks like

nginx-container:
    image: nginx:1.13
    ports: 
        - "8083:80"
    volumes: 
        - './ngnix.conf:/etc/ngnix/nginx.conf'
    networks:
      default:
        aliases:
          - 'nginx-container.localhost.localdomain'
    depends_on: 
        - jboss 

The nginx.conf looks like

events { worker_connections 1024;}
http {
    upstream app {
        server jboss:8080;
    }
}

I have configured my appliaction so that the request goes through port 8083 ( assigned for Nginx), and so the request url now looks like

https://localhost:8083/AppName/serviceName/methodName

But I am receiving

java.net.ConnectException: java.net.ConnectException: Connection refused (Connection refused)(https://localhost:8083/AppName/serviceName/methodName)

I am sure I have done ( many) things wrong, but so far unable to pinpoint it. Any help is appreciated.