[#69] Set GOOGLE_APPLICATION_CREDENTIALS with a temp credentials file (#70)

* [#69] Set GOOGLE_APPLICATION_CREDENTIALS with a temp credentials file

This change sets the GOOGLE_APPLICATION_CREDENTIALS environment variable to a temporary file that contains the service account credentials.

* Apply code review

app.py

@@ -8,6 +8,8 @@ from firebase_admin import firestore
 import gradio as gr
 import lingua
 
+import credentials
+from credentials import set_credentials
 from leaderboard import build_leaderboard
 from leaderboard import db
 from leaderboard import SUPPORTED_TRANSLATION_LANGUAGES
@@ -186,6 +188,8 @@ with gr.Blocks(title="Arena", css=css) as app:
   build_leaderboard()
 
 if __name__ == "__main__":
+  set_credentials(credentials.CREDENTIALS, credentials.CREDENTIALS_PATH)
+
   # We need to enable queue to use generators.
   app.queue()
   app.launch(debug=True)

credentials.py

@@ -5,6 +5,8 @@ required for authentication with GCP services.
 
 import json
 import os
+import stat
+import tempfile
 
 # Path to local credentials file, used in local development.
 CREDENTIALS_PATH = os.environ.get("CREDENTIALS_PATH")
@@ -13,6 +15,27 @@ CREDENTIALS_PATH = os.environ.get("CREDENTIALS_PATH")
 CREDENTIALS = os.environ.get("CREDENTIALS")
 
 
+def set_credentials(credentials: str = None, credentials_path: str = None):
+  if not credentials and not credentials_path:
+    raise ValueError(
+        "No credentials found. Ensure credentials or credentials path is set.")
+
+  if credentials_path:
+    if os.path.exists(credentials_path):
+      os.environ["GOOGLE_APPLICATION_CREDENTIALS"] = credentials_path
+      return
+    raise FileNotFoundError(f"Credentials file not found: {credentials_path}")
+
+  # Create a temporary file to store credentials for
+  # services that don't accept string format credentials.
+  with tempfile.NamedTemporaryFile(mode="w", suffix=".json",
+                                   delete=False) as cred_file:
+    cred_file.write(credentials)
+    os.chmod(cred_file.name, stat.S_IRUSR)
+    os.environ["GOOGLE_APPLICATION_CREDENTIALS"] = cred_file.name
+
+
+# TODO(#69): Replace get_credentials_json with set_credentials.
 def get_credentials_json():
   if not CREDENTIALS and not CREDENTIALS_PATH:
     raise ValueError(