Add .env file in the root and add the config variables for firebase,
API_KEY=AIzaSyCrOpA4qWg...................
AUTH_DOMAIN=cygnus-website.....firebaseapp.com
PROJECT_ID=cygnus-website.......
STORAGE_BUCKET=cygnus-website.....appspot.com
MESSAGING_SENDER_ID=1148......
APP_ID=1:11...........:web:cdef.............