fix(backup): Pull correct GCP credentials file path (#60038)

src/sentry/utils/env.py

@@ -1,6 +1,7 @@
 import os
 import sys
 
+import requests
 from django.conf import settings
 
 from sentry.utils import json
@@ -14,12 +15,22 @@ def gcp_project_id() -> str:
     if in_test_environment():
         return "__test_gcp_project__"
 
-    adc_path = os.environ.get("GOOGLE_APPLICATION_CREDENTIALS", "")
-    if adc_path:
-        with open(adc_path) as fp:
-            adc = json.load(fp)
-            if adc.get("quota_project_id") is not None:
-                return adc.get("quota_project_id")
+    # Try the metadata endpoint, if possible. If not, we'll assume a local environment as use the
+    # app credentials env variable instead.
+    try:
+        return requests.get(
+            "http://metadata.google.internal/computeMetadata/v1/project/project-id",
+            headers={
+                "Metadata-Flavor": "Google",
+            },
+        ).text
+    except requests.exceptions.RequestException:
+        adc_path = os.environ.get("GOOGLE_APPLICATION_CREDENTIALS", "")
+        if adc_path:
+            with open(adc_path) as fp:
+                adc = json.load(fp)
+                if adc.get("quota_project_id") is not None:
+                    return adc.get("quota_project_id")
 
     return "__unknown_gcp_project__"