Merge pull request terraform-google-modules#284 from omazin/master

[wait-for-cluster.sh] Set CLOUDSDK_AUTH_CREDENTIAL_FILE_OVERRIDE.

scripts/wait-for-cluster.sh

@@ -1,5 +1,5 @@
 #!/bin/bash
-# Copyright 2018 Google LLC
+# Copyright 2019 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -15,6 +15,10 @@
 
 set -e
 
+if [ -n "${GOOGLE_APPLICATION_CREDENTIALS}" ]; then
+    CLOUDSDK_AUTH_CREDENTIAL_FILE_OVERRIDE=${GOOGLE_APPLICATION_CREDENTIALS}
+fi
+
 PROJECT=$1
 CLUSTER_NAME=$2
 gcloud_command="gcloud container clusters list --project=$PROJECT --format=json"