How to print environment variables on Heroku?
The heroku run command runs a one-off process inside a Heroku dyno. The unix command that prints environment variables is printenv (manual page). Thus
heroku run -a app-name printenvis the command you are looking for.
step 1 : list your apps
heroku appsCopy the name of your app
step 2 : view config variables of this app
heroku config -a acme-web