portdiscovery

Finds an open port and sends the output to stdout

portdiscovery

Finds an open port (using portfinder) and sends output to stdout

npm install -g portdiscovery

Simply run portdiscovery and it will look for open ports starting in 8000.

You can specify a base port if 8000 doesn't fit your needs: portdiscovery 8010

You can assign to a bash variable then use it to deploy your apps, for example:

httpPort=$(portdiscovery)
echo $httpPort