Catch error in sdk when workflow instance not found (#771)

* Catch error in sdk when workflow instance not found

Signed-off-by: Elena Kolevska <elena@kolevska.com>

* fixes demo workflow example test

Signed-off-by: Elena Kolevska <elena@kolevska.com>

* Only return None for the correct error

Signed-off-by: Elena Kolevska <elena@kolevska.com>

* Adds test

Signed-off-by: Elena Kolevska <elena@kolevska.com>

* Linter

Signed-off-by: Elena Kolevska <elena@kolevska.com>

* Extends test

Signed-off-by: Elena Kolevska <elena@kolevska.com>

---------

Signed-off-by: Elena Kolevska <elena@kolevska.com>

examples/demo_workflow/app.py

@@ -139,13 +139,17 @@ def main():
 
         # Pause Test
         d.pause_workflow(instance_id=instance_id, workflow_component=workflow_component)
+        sleep(3)
+
         get_response = d.get_workflow(
             instance_id=instance_id, workflow_component=workflow_component
         )
         print(f'Get response from {workflow_name} after pause call: {get_response.runtime_status}')
 
         # Resume Test
         d.resume_workflow(instance_id=instance_id, workflow_component=workflow_component)
+        sleep(3)
+
         get_response = d.get_workflow(
             instance_id=instance_id, workflow_component=workflow_component
         )

examples/workflow/monitor.py

@@ -68,6 +68,7 @@ def send_alert(ctx, message: str):
         status = wf_client.get_workflow_state(job_id)
     except Exception:
         pass
+
     if not status or status.runtime_status.name != 'RUNNING':
         # TODO update to use reuse_id_policy
         instance_id = wf_client.schedule_new_workflow(

ext/dapr-ext-workflow/dapr/ext/workflow/dapr_workflow_client.py

@@ -24,6 +24,7 @@
 from dapr.ext.workflow.workflow_state import WorkflowState
 from dapr.ext.workflow.workflow_context import Workflow
 from dapr.ext.workflow.util import getAddress
+from grpc import RpcError
 
 from dapr.clients import DaprInternalError
 from dapr.clients.http.client import DAPR_API_TOKEN_HEADER
@@ -130,8 +131,17 @@ def get_workflow_state(
             exist.
 
         """
-        state = self.__obj.get_orchestration_state(instance_id, fetch_payloads=fetch_payloads)
-        return WorkflowState(state) if state else None
+        try:
+            state = self.__obj.get_orchestration_state(instance_id, fetch_payloads=fetch_payloads)
+            return WorkflowState(state) if state else None
+        except RpcError as error:
+            if 'no such instance exists' in error.details():
+                self._logger.warning(f'Workflow instance not found: {instance_id}')
+                return None
+            self._logger.error(
+                f'Unhandled RPC error while fetching workflow state: {error.code()} - {error.details()}'
+            )
+            raise
 
     def wait_for_workflow_start(
         self, instance_id: str, *, fetch_payloads: bool = False, timeout_in_seconds: int = 60

ext/dapr-ext-workflow/tests/test_workflow_client.py

@@ -21,6 +21,7 @@
 from dapr.ext.workflow.dapr_workflow_client import DaprWorkflowClient
 from durabletask import client
 import durabletask.internal.orchestrator_service_pb2 as pb
+from grpc import RpcError
 
 mock_schedule_result = 'workflow001'
 mock_raise_event_result = 'event001'
@@ -29,6 +30,19 @@
 mock_resume_result = 'resume001'
 mock_purge_result = 'purge001'
 mock_instance_id = 'instance001'
+wf_status = 'not-found'
+
+
+class SimulatedRpcError(RpcError):
+    def __init__(self, code, details):
+        self._code = code
+        self._details = details
+
+    def code(self):
+        return self._code
+
+    def details(self):
+        return self._details
 
 
 class FakeTaskHubGrpcClient:
@@ -43,7 +57,15 @@ def schedule_new_orchestration(
         return mock_schedule_result
 
     def get_orchestration_state(self, instance_id, fetch_payloads):
-        return self._inner_get_orchestration_state(instance_id, client.OrchestrationStatus.PENDING)
+        global wf_status
+        if wf_status == 'not-found':
+            raise SimulatedRpcError(code='UNKNOWN', details='no such instance exists')
+        elif wf_status == 'found':
+            return self._inner_get_orchestration_state(
+                instance_id, client.OrchestrationStatus.PENDING
+            )
+        else:
+            raise SimulatedRpcError(code='UNKNOWN', details='unknown error')
 
     def wait_for_orchestration_start(self, instance_id, fetch_payloads, timeout):
         return self._inner_get_orchestration_state(instance_id, client.OrchestrationStatus.RUNNING)
@@ -100,6 +122,20 @@ def test_client_functions(self):
             )
             assert actual_schedule_result == mock_schedule_result
 
+            global wf_status
+            wf_status = 'not-found'
+            actual_get_result = wfClient.get_workflow_state(
+                instance_id=mock_instance_id, fetch_payloads=True
+            )
+            assert actual_get_result is None
+
+            wf_status = 'error'
+            with self.assertRaises(RpcError):
+                wfClient.get_workflow_state(instance_id=mock_instance_id, fetch_payloads=True)
+
+            assert actual_get_result is None
+
+            wf_status = 'found'
             actual_get_result = wfClient.get_workflow_state(
                 instance_id=mock_instance_id, fetch_payloads=True
             )