12 factor app: environment variables

Use the dotenv library to read both a file called .env, as well as inspect
environment variables.
In addition, provide some checking and sanitization on the PUMP_SERIAL_NUMBER
along with an error message for commonly anticipated issues.

secret.py

@@ -0,0 +1,31 @@
+import os, sys
+from dotenv import load_dotenv
+load_dotenv( )
+
+TCONNECT_EMAIL = os.environ.get('TCONNECT_EMAIL', 'email@email.com')
+TCONNECT_PASSWORD = os.environ.get('TCONNECT_PASSWORD', 'password')
+
+try:
+  PUMP_SERIAL_NUMBER = int(os.environ.get('PUMP_SERIAL_NUMBER', '11111111'))
+  if (len(str(PUMP_SERIAL_NUMBER)) < 8):
+    print("""PUMP_SERIAL_NUMBER should be a number.
+  Please review the following which is not a number.
+  PUMP_SERIAL_NUMBER={}""".format(os.environ.get('PUMP_SERIAL_NUMBER')))
+    sys.exit(1)
+except ValueError as e:
+  print("""PUMP_SERIAL_NUMBER must be a number.
+Please review the following which is not a number.
+PUMP_SERIAL_NUMBER={}""".format(os.environ.get('PUMP_SERIAL_NUMBER')))
+  sys.exit(1)
+
+NS_URL = os.environ.get('NS_URL', 'https://yournightscouturl/')
+NS_SECRET = os.environ.get('NS_SECRET', 'apisecret')
+
+TIMEZONE_NAME = os.environ.get('TIMEZONE_NAME', 'America/New_York')
+_config = ['TCONNECT_EMAIL', 'TCONNECT_PASSWORD', 'PUMP_SERIAL_NUMBER',
+          'NS_URL', 'NS_SECRET', 'TIMEZONE_NAME']
+
+if __name__ == '__main__':
+  for k in _config:
+    print("{}: {}".format( k, locals( ).get(k)))
+