Add root_execution_id to sub-workflow executions

For sub-workflow executions this will be the ID of the initial workflow
execution. For example, given the following workflows.

workflows:
  wf1:
    tasks:
      task1:
        workflow: wf2

  wf2:
    tasks:
      task1:
        workflow: wf3

  wf3:
    tasks:
      task1:
        action: std.noop

When we start wf1, it calls wf2 which calls wf3. Currently, it is hard to
retrieve the full execution, including sub-workflow executions. This patch adds
the root_execution_id to the sub-workflows, so the execution for wf2 and wf3
have a root_execution_id that is the ID of the execution for wf1. The execution
for wf1 is the root execution, so root_execution_id is None. This basically
gives us a flat reference to the graph of workflow executions.

This change is useful as we can then expose it via the API and it makes
it easier and more efficient to find a full execution, including it's
sub-workflow executions.

Implements: blueprint mistral-root-execution-id
Change-Id: I24638812caa2e48e3c071925db5e552b21e15d47

mistral/db/sqlalchemy/migration/alembic_migrations/versions/023_add_root_execution_id.py

@@ -0,0 +1,36 @@
+# Copyright 2015 OpenStack Foundation.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Add the root execution ID to the workflow execution model
+
+Revision ID: 023
+Revises: 022
+Create Date: 2017-07-26 14:51:02.384729
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '023'
+down_revision = '022'
+
+from alembic import op
+import sqlalchemy as sa
+
+
+def upgrade():
+    op.add_column(
+        'workflow_executions_v2',
+        sa.Column('root_execution_id', sa.String(length=80), nullable=True)
+    )

mistral/db/v2/sqlalchemy/models.py

@@ -317,6 +317,14 @@ sa.Index(
     'task_execution_id'
 )
 
+# Many-to-one for 'WorkflowExecution' and 'WorkflowExecution'
+
+WorkflowExecution.root_execution_id = sa.Column(
+    sa.String(36),
+    sa.ForeignKey(WorkflowExecution.id, ondelete='SET NULL'),
+    nullable=True
+)
+
 # Many-to-one for 'TaskExecution' and 'WorkflowExecution'.
 
 TaskExecution.workflow_execution_id = sa.Column(

mistral/engine/actions.py

@@ -534,7 +534,13 @@ class WorkflowAction(Action):
             wf_def.updated_at
         )
 
+        # If the parent has a root_execution_id, it must be a sub-workflow. So
+        # we should propogate that ID down. Otherwise the parent must be the
+        # root execution and we should use the parents ID.
+        root_execution_id = parent_wf_ex.root_execution_id or parent_wf_ex.id
+
         wf_params = {
+            'root_execution_id': root_execution_id,
             'task_execution_id': self.task_ex.id,
             'index': index,
             'namespace': parent_wf_ex.params['namespace']

mistral/engine/workflows.py

@@ -270,6 +270,7 @@ class Workflow(object):
             'state': states.IDLE,
             'output': {},
             'task_execution_id': params.get('task_execution_id'),
+            'root_execution_id': params.get('root_execution_id'),
             'runtime_context': {
                 'index': params.get('index', 0)
             },

mistral/tests/unit/engine/test_subworkflows.py

@@ -187,7 +187,29 @@ workflows:
     tasks:
         task1:
             action: std.noop
+"""
 
+WB6 = """
+---
+version: '2.0'
+
+name: wb6
+
+workflows:
+  wf1:
+    tasks:
+      task1:
+        workflow: wf2
+
+  wf2:
+    tasks:
+      task1:
+        workflow: wf3
+
+  wf3:
+    tasks:
+      task1:
+        action: std.noop
 """
 
 
@@ -200,6 +222,7 @@ class SubworkflowsTest(base.EngineTestCase):
         wb_service.create_workbook_v2(WB3)
         wb_service.create_workbook_v2(WB4)
         wb_service.create_workbook_v2(WB5)
+        wb_service.create_workbook_v2(WB6)
 
     def test_subworkflow_success(self):
         wf2_ex = self.engine.start_workflow('wb1.wf2', '', None)
@@ -409,3 +432,28 @@ class SubworkflowsTest(base.EngineTestCase):
         with db_api.transaction():
             ex = db_api.get_workflow_execution(ex.id)
             self.assertEqual({'sub_wf_out': 'abc'}, ex.output)
+
+    def test_subworkflow_root_execution_id(self):
+        wf1_ex = self.engine.start_workflow('wb6.wf1', '', None)
+
+        self._await(lambda: len(db_api.get_workflow_executions()) == 3, 0.5, 5)
+
+        wf_execs = db_api.get_workflow_executions()
+        wf1_ex = self._assert_single_item(wf_execs, name='wb6.wf1')
+        wf2_ex = self._assert_single_item(wf_execs, name='wb6.wf2')
+        wf3_ex = self._assert_single_item(wf_execs, name='wb6.wf3')
+
+        self.assertEqual(3, len(wf_execs))
+
+        # Wait till workflow 'wf1' is completed (and all the sub-workflows
+        # will be completed also).
+        self.await_workflow_success(wf1_ex.id)
+
+        with db_api.transaction():
+            wf1_ex = db_api.get_workflow_execution(wf1_ex.id)
+            wf2_ex = db_api.get_workflow_execution(wf2_ex.id)
+            wf3_ex = db_api.get_workflow_execution(wf3_ex.id)
+
+        self.assertIsNone(wf1_ex.root_execution_id, None)
+        self.assertEqual(wf2_ex.root_execution_id, wf1_ex.id)
+        self.assertEqual(wf3_ex.root_execution_id, wf1_ex.id)