Merge "Change message when no nodes found during update"

src/bin/shipyard_airflow/shipyard_airflow/plugins/drydock_verify_nodes.py

@@ -23,37 +23,57 @@ except ImportError:
         DrydockBaseOperator
 
 LOG = logging.getLogger(__name__)
+safeguard_message_header = (
+    "No nodes were found by Drydock. Safeguard triggered to prevent "
+    "continued deployment of nodes.")
+safeguard_message_body = (
+    "This condition can occur if update_site is invoked before a deploy_site "
+    "has previously deployed nodes in this site. If nodes are expected to be "
+    "present (previously deployed), this is a serious condition and should "
+    "be investigated. This behavior can be bypassed by setting "
+    "continue-on-fail to true.")
+safeguard_bypassed_message = (
+    "Nodes do not exist, but continue-on-fail is True. Safeguard bypassed by "
+    "invocation options.")
 
 
 class DrydockVerifyNodesExistOperator(DrydockBaseOperator):
-
     """Drydock Verify nodes exist Operator
 
-    This operator will trigger drydock to verify node for
-    site update
-
+    Check that ANY nodes exist.
+    One use of this is to prevent an update_site from redeploying servers if
+    the underlying datastores have lost their data. Doing this prevents
+    destruction of potentially running workloads.
     """
 
     def do_execute(self):
-
-        LOG.info('verify_nodes_exit was invoked.')
+        LOG.info("Verifying that nodes exist before proceeding.")
         node_list = self.get_nodes()
-        continue_on_fail = self.action_info['parameters'].get(
-            'continue-on-fail', 'false')
-        LOG.debug('node list is : {}'.format(node_list))
-        LOG.debug('continue on fail is: {}'.format(continue_on_fail))
+        if not node_list:
+            if self.continue_on_fail():
+                LOG.info(safeguard_bypassed_message)
+            else:
+                LOG.error(safeguard_message_header)
+                LOG.error(safeguard_message_body)
+                raise AirflowException(safeguard_message_header)
+        else:
+            LOG.info("Drydock reports nodes: %s", node_list)
 
-        if not node_list and str(continue_on_fail).lower() != 'true':
-            msg = 'No nodes were found in MaaS, ' \
-                  'and continue_on_fail is {} ' \
-                  '-> Fail Drydock prepare and ' \
-                  'deply nodes.'.format(continue_on_fail)
-            LOG.error(msg)
-            raise AirflowException(msg)
+    def continue_on_fail(self):
+        """Retrieve the continue_on_fail boolean value
+
+        Fetch the continue-on-fail value from the action_info parameters and
+        translate it into a boolean value.
+        """
+        continue_on_fail_str = str(self.action_info['parameters'].get(
+            'continue-on-fail', 'false'))
+        continue_on_fail = continue_on_fail_str.lower() == 'true'
+        LOG.debug("continue-on-fail value is: %s, evaluates to: %s",
+                  continue_on_fail_str, continue_on_fail)
+        return continue_on_fail
 
 
 class DrydockVerifyNodesExistOperatorPlugin(AirflowPlugin):
-
     """Creates DrydockVerifyNodesExistOperatorPlugin in Airflow."""
 
     name = 'drydock_verify_nodes_exist_operator'