feat: Use float instead of int for GCE_METADATA_TIMEOUT

google/auth/compute_engine/_metadata.py

@@ -96,10 +96,7 @@ def _get_metadata_ip_root(use_mtls: bool):
 
 # Timeout in seconds to wait for the GCE metadata server when detecting the
 # GCE environment.
-try:
-    _METADATA_DEFAULT_TIMEOUT = int(os.getenv(environment_vars.GCE_METADATA_TIMEOUT, 3))
-except ValueError:  # pragma: NO COVER
-    _METADATA_DEFAULT_TIMEOUT = 3
+_METADATA_PING_DEFAULT_TIMEOUT = 3
 
 # The number of tries to perform when waiting for the GCE metadata server
 # when detecting the GCE environment.
@@ -209,6 +206,16 @@ def ping(
     #       could lead to false negatives in the event that we are on GCE, but
     #       the metadata resolution was particularly slow. The latter case is
     #       "unlikely".
+
+    if timeout is None:
+        try:
+            timeout = float(os.getenv(
+                environment_vars.GCE_METADATA_TIMEOUT,
+                str(_METADATA_PING_DEFAULT_TIMEOUT)))
+        except ValueError:
+            timeout = _METADATA_PING_DEFAULT_TIMEOUT
+
+    retries = 0
     headers = _METADATA_HEADERS.copy()
     headers[metrics.API_CLIENT_HEADER] = metrics.mds_ping()
 

google/auth/environment_vars.py

@@ -94,6 +94,9 @@
 Used to distinguish between GAE gen1 and GAE gen2+.
 """
 
+GCE_METADATA_TIMEOUT = "GCE_METADATA_TIMEOUT"
+"""Environment variable for setting timeouts in seconds for metadata queries."""
+
 # AWS environment variables used with AWS workload identity pools to retrieve
 # AWS security credentials and the AWS region needed to create a serialized
 # signed requests to the AWS STS GetCalledIdentity API that can be exchanged

tests/compute_engine/test__metadata.py

@@ -143,9 +143,46 @@ def test_ping_success(mock_metrics_header_value):
 
     request.assert_called_once_with(
         method="GET",
-        url="http://169.254.169.254",
-        headers=MDS_PING_REQUEST_HEADER,
-        timeout=_metadata._METADATA_DEFAULT_TIMEOUT,
+        url=_metadata._METADATA_IP_ROOT,
+        headers=_metadata._METADATA_HEADER,
+        timeout=_metadata._METADATA_PING_DEFAULT_TIMEOUT,
+    )
+
+@mock.patch("google.auth.metrics.mds_ping", return_value=MDS_PING_METRICS_HEADER_VALUE)
+def test_ping_success_with_gce_metadata_timeout(mock_metrics_header_value):
+    request = make_request("", headers=_metadata._METADATA_HEADERS)
+    gce_metadata_timeout = .5
+    os.environ[
+        environment_vars.GCE_METADATA_TIMEOUT] = str(gce_metadata_timeout)
+
+    try:
+        assert _metadata.ping(request)
+    finally:
+        del os.environ[environment_vars.GCE_METADATA_TIMEOUT]
+
+    request.assert_called_once_with(
+        method="GET",
+        url=_metadata._METADATA_IP_ROOT,
+        headers=_metadata._METADATA_HEADER,
+        timeout=gce_metadata_timeout,
+    )
+
+@mock.patch("google.auth.metrics.mds_ping", return_value=MDS_PING_METRICS_HEADER_VALUE)
+def test_ping_success_with_invalid_gce_metadata_timeout(mock_metrics_header_value):
+    request = make_request("", headers=_metadata._METADATA_HEADERS)
+    os.environ[
+        environment_vars.GCE_METADATA_TIMEOUT] = "Not a valid float value!"
+
+    try:
+        assert _metadata.ping(request)
+    finally:
+        del os.environ[environment_vars.GCE_METADATA_TIMEOUT]
+
+    request.assert_called_once_with(
+        method="GET",
+        url=_metadata._METADATA_IP_ROOT,
+        headers=_metadata._METADATA_HEADERS,
+        timeout=_metadata._METADATA_PING_DEFAULT_TIMEOUT, # Fallback value.
     )
 
 
@@ -197,7 +234,7 @@ def test_ping_success_custom_root(mock_metrics_header_value):
         method="GET",
         url="http://" + fake_ip,
         headers=MDS_PING_REQUEST_HEADER,
-        timeout=_metadata._METADATA_DEFAULT_TIMEOUT,
+        timeout=_metadata._METADATA_PING_DEFAULT_TIMEOUT,
     )