Merge tag 'v0.21.0'

Author: nyergler

google/google.go

@@ -252,7 +252,10 @@ func (f *credentialsFile) tokenSource(ctx context.Context, params CredentialsPar
 // Further information about retrieving access tokens from the GCE metadata
 // server can be found at https://cloud.google.com/compute/docs/authentication.
 func ComputeTokenSource(account string, scope ...string) oauth2.TokenSource {
-	return computeTokenSource(account, 0, scope...)
+	// refresh 3 minutes and 45 seconds early. The shortest MDS cache is currently 4 minutes, so any
+	// refreshes earlier are a waste of compute.
+	earlyExpirySecs := 225 * time.Second
+	return computeTokenSource(account, earlyExpirySecs, scope...)
 }
 
 func computeTokenSource(account string, earlyExpiry time.Duration, scope ...string) oauth2.TokenSource {