Implements custom resource type managed by Mistral workflows

Adds a new resource named OS::Mistral::ExternalResource which
allow users to use custom resource types implementing their actions
as Mistral workflows.

Implements: blueprint mistral-new-resource-type-workflow-execution
Change-Id: If02799e7457ca017cc119317dfb2db7198a3559f

heat/engine/resources/openstack/mistral/external_resource.py

@@ -0,0 +1,282 @@
+#
+#    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.
+
+from oslo_log import log as logging
+from oslo_serialization import jsonutils
+import six
+
+from heat.common import exception
+from heat.common.i18n import _
+from heat.engine import attributes
+from heat.engine import constraints
+from heat.engine import properties
+from heat.engine import resource
+from heat.engine import support
+
+LOG = logging.getLogger(__name__)
+
+
+class MistralExternalResource(resource.Resource):
+    """A plugin for managing user-defined resources via Mistral workflows.
+
+    This resource allows users to manage resources that are not known to Heat.
+    The user may specify a Mistral workflow to handle each resource action,
+    such as CREATE, UPDATE, or DELETE.
+
+    The workflows may return an output named 'resource_id', which will be
+    treated as the physical ID of the resource by Heat.
+
+    Once the resource is created, subsequent workflow runs will receive the
+    output of the last workflow execution in the 'heat_extresource_data' key
+    in the workflow environment (accessible as ``env().heat_extresource_data``
+    in the workflow).
+
+    The template author may specify a subset of inputs as causing replacement
+    of the resource when they change, as an alternative to running the
+    UPDATE workflow.
+    """
+
+    support_status = support.SupportStatus(version='9.0.0')
+
+    default_client_name = 'mistral'
+
+    entity = 'executions'
+
+    _ACTION_PROPERTIES = (
+        WORKFLOW, PARAMS
+    ) = (
+        'workflow', 'params'
+    )
+
+    PROPERTIES = (
+        EX_ACTIONS,
+        INPUT,
+        DESCRIPTION,
+        REPLACE_ON_CHANGE,
+        ALWAYS_UPDATE
+    ) = (
+        'actions',
+        'input',
+        'description',
+        'replace_on_change_inputs',
+        'always_update'
+    )
+
+    ATTRIBUTES = (
+        OUTPUT,
+    ) = (
+        'output',
+    )
+
+    _action_properties_schema = properties.Schema(
+        properties.Schema.MAP,
+        _('Dictionary which defines the workflow to run and its params.'),
+        schema={
+            WORKFLOW: properties.Schema(
+                properties.Schema.STRING,
+                _('Workflow to execute.'),
+                required=True,
+                constraints=[
+                    constraints.CustomConstraint('mistral.workflow')
+                ],
+            ),
+            PARAMS: properties.Schema(
+                properties.Schema.MAP,
+                _('Workflow additional parameters. If workflow is reverse '
+                  'typed, params requires "task_name", which defines '
+                  'initial task.'),
+                default={}
+            ),
+        }
+    )
+
+    properties_schema = {
+        EX_ACTIONS: properties.Schema(
+            properties.Schema.MAP,
+            _('Resource action which triggers a workflow execution.'),
+            schema={
+                resource.Resource.CREATE: _action_properties_schema,
+                resource.Resource.UPDATE: _action_properties_schema,
+                resource.Resource.SUSPEND: _action_properties_schema,
+                resource.Resource.RESUME: _action_properties_schema,
+                resource.Resource.DELETE: _action_properties_schema,
+            },
+            required=True
+        ),
+        INPUT: properties.Schema(
+            properties.Schema.MAP,
+            _('Dictionary which contains input for the workflows.'),
+            update_allowed=True,
+            default={}
+        ),
+        DESCRIPTION: properties.Schema(
+            properties.Schema.STRING,
+            _('Workflow execution description.'),
+            default='Heat managed'
+        ),
+        REPLACE_ON_CHANGE: properties.Schema(
+            properties.Schema.LIST,
+            _('A list of inputs that should cause the resource to be replaced '
+              'when their values change.'),
+            default=[]
+        ),
+        ALWAYS_UPDATE: properties.Schema(
+            properties.Schema.BOOLEAN,
+            _('Triggers UPDATE action execution even if input is '
+              'unchanged.'),
+            default=False
+        ),
+    }
+
+    attributes_schema = {
+        OUTPUT: attributes.Schema(
+            _('Output from the execution.'),
+            type=attributes.Schema.MAP
+        ),
+    }
+
+    def _check_execution(self, action, execution_id):
+        """Check execution status.
+
+        Returns False if in IDLE, RUNNING or PAUSED
+        returns True if in SUCCESS
+        raises ResourceFailure if in ERROR, CANCELLED
+        raises ResourceUnknownState otherwise.
+        """
+        execution = self.client().executions.get(execution_id)
+        LOG.debug('Mistral execution %(id)s is in state '
+                  '%(state)s' % {'id': execution_id,
+                                 'state': execution.state})
+
+        if execution.state in ('IDLE', 'RUNNING', 'PAUSED'):
+            return False, {}
+
+        if execution.state in ('SUCCESS',):
+            return True, jsonutils.loads(execution.output)
+
+        if execution.state in ('ERROR', 'CANCELLED'):
+            raise exception.ResourceFailure(
+                exception_or_error=execution.state,
+                resource=self,
+                action=action)
+
+        raise exception.ResourceUnknownStatus(
+            resource_status=execution.state,
+            result=_('Mistral execution is in unknown state.'))
+
+    def _handle_action(self, action, inputs=None):
+        action_data = self.properties[self.EX_ACTIONS].get(action)
+        if action_data:
+            # bring forward output from previous executions into env
+            if self.resource_id:
+                old_outputs = jsonutils.loads(self.data().get('outputs', '{}'))
+                action_env = action_data[self.PARAMS].get('env', {})
+                action_env['heat_extresource_data'] = old_outputs
+                action_data[self.PARAMS]['env'] = action_env
+            # inputs is not None when inputs changed on stack UPDATE
+            if not inputs:
+                inputs = self.properties[self.INPUT]
+            execution = self.client().executions.create(
+                action_data[self.WORKFLOW],
+                jsonutils.dumps(inputs),
+                self.properties[self.DESCRIPTION],
+                **action_data[self.PARAMS])
+            LOG.debug('Mistral execution %(id)s params set to '
+                      '%(params)s' % {'id': execution.id,
+                                      'params': action_data[self.PARAMS]})
+            return execution.id
+
+    def _check_action(self, action, execution_id):
+        success = True
+        # execution_id is None when no data is available for a given action
+        if execution_id:
+            rsrc_id = execution_id
+            success, output = self._check_execution(action, execution_id)
+            # merge output with outputs of previous executions
+            outputs = jsonutils.loads(self.data().get('outputs', '{}'))
+            outputs.update(output)
+            self.data_set('outputs', jsonutils.dumps(outputs))
+            # set resource id using output, if found
+            if output.get('resource_id'):
+                rsrc_id = output.get('resource_id')
+                LOG.debug('ExternalResource id set to %(rid)s from Mistral '
+                          'execution %(eid)s output' % {'eid': execution_id,
+                                                        'rid': rsrc_id})
+            self.resource_id_set(six.text_type(rsrc_id)[:255])
+        return success
+
+    def _resolve_attribute(self, name):
+        if self.resource_id and name == self.OUTPUT:
+            return self.data().get('outputs')
+
+    def _needs_update(self, after, before, after_props, before_props,
+                      prev_resource, check_init_complete=True):
+        # check if we need to force replace first
+        old_inputs = before_props[self.INPUT]
+        new_inputs = after_props[self.INPUT]
+        for i in after_props[self.REPLACE_ON_CHANGE]:
+            if old_inputs.get(i) != new_inputs.get(i):
+                LOG.debug('Replacing ExternalResource %(id)s instead of '
+                          'updating due to change to input "%(i)s"' %
+                          {"id": self.resource_id,
+                           "i": i})
+                raise resource.UpdateReplace(self)
+        # honor always_update if found
+        if self.properties[self.ALWAYS_UPDATE]:
+            return True
+        # call super in all other scenarios
+        else:
+            return super(MistralExternalResource,
+                         self)._needs_update(after,
+                                             before,
+                                             after_props,
+                                             before_props,
+                                             prev_resource,
+                                             check_init_complete)
+
+    def handle_create(self):
+        return self._handle_action(self.CREATE)
+
+    def check_create_complete(self, execution_id):
+        return self._check_action(self.CREATE, execution_id)
+
+    def handle_update(self, json_snippet, tmpl_diff, prop_diff):
+        new_inputs = prop_diff.get(self.INPUT)
+        return self._handle_action(self.UPDATE, new_inputs)
+
+    def check_update_complete(self, execution_id):
+        return self._check_action(self.UPDATE, execution_id)
+
+    def handle_suspend(self):
+        return self._handle_action(self.SUSPEND)
+
+    def check_suspend_complete(self, execution_id):
+        return self._check_action(self.SUSPEND, execution_id)
+
+    def handle_resume(self):
+        return self._handle_action(self.RESUME)
+
+    def check_resume_complete(self, execution_id):
+        return self._check_action(self.RESUME, execution_id)
+
+    def handle_delete(self):
+        return self._handle_action(self.DELETE)
+
+    def check_delete_complete(self, execution_id):
+        return self._check_action(self.DELETE, execution_id)
+
+
+def resource_mapping():
+    return {
+        'OS::Mistral::ExternalResource': MistralExternalResource
+    }