config vagrant, nginx and node for load balancing

Setup Vagrant + nginx + nodejs

setup seperate vagrant box for nginx and node app, assign different ips for each box.
write script file in vagrant box and config in Vagrantfile:
    config.vm.provision "shell", path: "script.sh"

        ------- script.sh --------
 
        echo "---- start setting up ------"

        echo "---- update package list ----"
        sudo apt-get update

        echo "---- install nvm ----"
        curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.32.1/install.sh | bash
        source $HOME/.nvm/nvm.sh

        echo "---- install nodejs ----"
        nvm install stable
        nvm alias default stable

        echo "---- install express ----"
        npm install -g express-generator


and then reload the vagrant:
    vagrant reload --provision
    

upstream module in nginx:

    upstream app_name {
            server srv1.example.com;
            server srv2.example.com;
            server srv3.example.com;
    }

    server {
        listen 80;

        location / {
            proxy_pass http://app_name;
        }
    }
    
run Apache Bench testing
-install: sudo apt install apache2-utils
-ab -c 40 -n 1000 http://ip.address/
    -n requests     Number of requests to perform
    -c concurrency  Number of multiple requests to make
    see more: https://www.petefreitag.com/item/689.cfm