Fix deployment execution fetching

The auto deployments feature required creation of deployments
without executions, making it unsafe to presume the deployment
will have an execution at any time. This patch fixes this by
checking that the deployment has an execution, before trying
to access it for operations like deployment deletion or
cancellation.

coriolis/conductor/rpc/server.py

@@ -1352,11 +1352,12 @@ class ConductorServerEndpoint(object):
             ctxt, deployment_id, include_task_info=include_task_info,
             to_dict=True)
 
-    @staticmethod
-    def _check_running_transfer_deployments(ctxt, transfer_id):
+    def _check_running_transfer_deployments(self, ctxt, transfer_id):
         deployments = db_api.get_transfer_deployments(ctxt, transfer_id)
         for d in deployments:
-            if d.executions and d.executions[0].status in (
+            execution = self._get_execution_for_deployment(
+                ctxt, d, raise_on_executions_empty=False)
+            if execution and execution.status in (
                     constants.ACTIVE_EXECUTION_STATUSES):
                 raise exception.InvalidTransferState(
                     "Transfer '%s' is currently being deployed" % transfer_id)
@@ -1803,14 +1804,17 @@ class ConductorServerEndpoint(object):
             transfer.executions, key=lambda e: e.number)[-1]
         return last_transfer_execution
 
-    def _get_execution_for_deployment(self, ctxt, deployment, requery=False):
+    def _get_execution_for_deployment(self, ctxt, deployment, requery=False,
+                                      raise_on_executions_empty=True):
         if requery:
             deployment = self._get_deployment(ctxt, deployment.id)
 
         if not deployment.executions:
-            raise exception.InvalidDeploymentState(
-                "Deployment with ID '%s' has no existing executions." % (
-                    deployment.id))
+            if raise_on_executions_empty:
+                raise exception.InvalidDeploymentState(
+                    "Deployment with ID '%s' has no existing executions." % (
+                        deployment.id))
+            return None
         if len(deployment.executions) > 1:
             raise exception.InvalidDeploymentState(
                 "Deployment with ID '%s' has more than one execution:"
@@ -1924,11 +1928,13 @@ class ConductorServerEndpoint(object):
 
     def _delete_deployment(self, ctxt, deployment_id):
         deployment = self._get_deployment(ctxt, deployment_id)
-        execution = deployment.executions[0]
-        if execution.status in constants.ACTIVE_EXECUTION_STATUSES:
-            raise exception.InvalidDeploymentState(
-                "Cannot delete Deployment '%s' as it is currently in "
-                "'%s' state." % (deployment_id, execution.status))
+        execution = self._get_execution_for_deployment(
+            ctxt, deployment, raise_on_executions_empty=False)
+        if execution:
+            if execution.status in constants.ACTIVE_EXECUTION_STATUSES:
+                raise exception.InvalidDeploymentState(
+                    "Cannot delete Deployment '%s' as it is currently in "
+                    "'%s' state." % (deployment_id, execution.status))
         db_api.delete_deployment(ctxt, deployment_id)
 
     @deployment_synchronized
@@ -1941,15 +1947,17 @@ class ConductorServerEndpoint(object):
             raise exception.InvalidDeploymentState(
                 "Deployment '%s' has in improper number of tasks "
                 "executions: %d" % (deployment_id, len(deployment.executions)))
-        execution = deployment.executions[0]
-        if execution.status not in constants.ACTIVE_EXECUTION_STATUSES:
-            raise exception.InvalidDeploymentState(
-                "Deployment '%s' is not currently running" % deployment_id)
-        if execution.status == constants.EXECUTION_STATUS_CANCELLING and (
-                not force):
-            raise exception.InvalidDeploymentState(
-                "Deployment '%s' is already being cancelled. Please use the "
-                "force option if you'd like to force-cancel it.")
+        execution = self._get_execution_for_deployment(
+            ctxt, deployment, raise_on_executions_empty=False)
+        if execution:
+            if execution.status not in constants.ACTIVE_EXECUTION_STATUSES:
+                raise exception.InvalidDeploymentState(
+                    "Deployment '%s' is not currently running" % deployment_id)
+            if execution.status == constants.EXECUTION_STATUS_CANCELLING and (
+                    not force):
+                raise exception.InvalidDeploymentState(
+                    "Deployment '%s' is already being cancelled. Please use "
+                    "the force option if you'd like to force-cancel it.")
 
         with lockutils.lock(
                 constants.EXECUTION_LOCK_NAME_FORMAT % execution.id,