Use default application credential

Author: kroikie

config/README.md

@@ -15,7 +15,7 @@ Getting started
 
 1. [Add Firebase to your Android Project](https://firebase.google.com/docs/android/setup).
 2. Create a service account as described in [Adding Firebase to your Server](https://firebase.google.com/docs/admin/setup) and download the JSON file.
-  - Copy the private key JSON file to this folder and rename it to `service-account.json`.
+  - Set `GOOGLE_APPLICATION_CREDENTIALS` environment variable to path of downloaded credential file.
 3. Change the `PROJECT_ID` variable in `configure.py` to your project ID.
 
 Run

config/configure.py

@@ -15,10 +15,13 @@
 def _get_access_token():
   """Retrieve a valid access token that can be used to authorize requests.
 
+  This method assumes it is either running in a trusted Google environment like GCP or if running
+  elsewhere the the GOOGLE_APPLICATION_CREDENTIALS environment variable is set to the path of the
+  service account credentials file.
+
   :return: Access token.
   """
-  credentials = ServiceAccountCredentials.from_json_keyfile_name(
-      'service-account.json', SCOPES)
+  credentials = ServiceAccountCredentials.get_application_default().create_scoped(scopes=SCOPES)
   access_token_info = credentials.get_access_token()
   return access_token_info.access_token
 # [END retrieve_access_token]