Activate account when SERVICE_ACCOUNT_EMAIL is provided (#56)

* Activate account when SERVICE_ACCOUNT_EMAIL is provided

Author: armandomiani

scripts/build-vm-image.sh

@@ -42,7 +42,12 @@ function _register_gcloud_config() {
 
 
 if [[ -v SERVICE_ACCOUNT_EMAIL ]]; then
+  declare -r active_account="$(gcloud auth list \
+                                --filter "status:ACTIVE" \
+                                --format "value(account)")"
+
   _register_gcloud_config
+  gcloud config set account "${active_account}"
 else
   # If the service account e-mail is not specified, check that the
   # key file is mounted.
@@ -58,7 +63,6 @@ fi
 
 # Print environment variables.
 env
-
 gcloud info
 
 # Set default value for unset variables.