Added examples for error scenarios in multi-app workflow

Signed-off-by: Albert Callarisa <[email protected]>

Author: acroca

examples/workflow/README.md

@@ -291,11 +291,10 @@ expected_stdout_lines:
   - '== APP == app1 - received workflow result'
   - '== APP == app1 - returning workflow result'
 background: true
-sleep: 5
+sleep: 20
 -->
 
 ```sh
-pip install ./ext/dapr-ext-workflow
 dapr run --app-id wfexample3 --dapr-grpc-port 50003 python3 cross-app3.py &
 dapr run --app-id wfexample2 --dapr-grpc-port 50002 python3 cross-app2.py &
 dapr run --app-id wfexample1 --dapr-grpc-port 50001 python3 cross-app1.py
@@ -310,3 +309,89 @@ app2 - triggering app3 activity
 ...
 ```
 among others. This shows that the workflow calls are working as expected.
+
+
+#### Error handling on activity calls
+
+This example demonstrates how the error handling works on activity calls across apps.
+
+Error handling on activity calls across apps works as normal workflow activity calls.
+
+In this example we run `app3` in failing mode, which makes the activity call return error constantly. The activity call from `app2` will fail after the retry policy is exhausted.
+
+<!-- STEP
+name: Run apps
+expected_stdout_lines:
+  - '== APP == app1 - triggering app1 workflow'
+  - '== APP == app1 - received workflow call'
+  - '== APP == app1 - triggering app2 workflow'
+  - '== APP == app2 - received workflow call'
+  - '== APP == app2 - triggering app3 activity'
+  - '== APP == app3 - received activity call'
+  - '== APP == app3 - raising error in activity due to error mode being enabled'
+  - '== APP == app2 - received activity error from app3'
+  - '== APP == app2 - returning workflow result'
+  - '== APP == app1 - received workflow result'
+  - '== APP == app1 - returning workflow result'
+sleep: 20
+-->
+
+```sh
+export ERROR_ACTIVITY_MODE=true
+dapr run --app-id wfexample3 --dapr-grpc-port 50013 python3 cross-app3.py &
+dapr run --app-id wfexample2 --dapr-grpc-port 50012 python3 cross-app2.py &
+dapr run --app-id wfexample1 --dapr-grpc-port 50011 python3 cross-app1.py
+```
+<!-- END_STEP -->
+
+
+When you run the apps with the `ERROR_ACTIVITY_MODE` environment variable set, you will see output like this:
+```
+...
+app3 - received activity call
+app3 - raising error in activity due to error mode being enabled
+app2 - received activity error from app3
+...
+```
+among others. This shows that the activity calls are failing as expected, and they are being handled as expected too.
+
+
+#### Error handling on workflow calls
+
+This example demonstrates how the error handling works on workflow calls across apps.
+
+Error handling on workflow calls across apps works as normal workflow calls.
+
+In this example we run `app2` in failing mode, which makes the workflow call return error constantly. The workflow call from `app1` will fail after the retry policy is exhausted.
+
+<!-- STEP
+name: Run apps
+expected_stdout_lines:
+  - '== APP == app1 - triggering app1 workflow'
+  - '== APP == app1 - received workflow call'
+  - '== APP == app1 - triggering app2 workflow'
+  - '== APP == app2 - received workflow call'
+  - '== APP == app2 - raising error in workflow due to error mode being enabled'
+  - '== APP == app1 - received workflow error from app2'
+  - '== APP == app1 - returning workflow result'
+sleep: 20
+-->
+
+```sh
+export ERROR_WORKFLOW_MODE=true
+dapr run --app-id wfexample3 --dapr-grpc-port 50023 python3 cross-app3.py &
+dapr run --app-id wfexample2 --dapr-grpc-port 50022 python3 cross-app2.py &
+dapr run --app-id wfexample1 --dapr-grpc-port 50021 python3 cross-app1.py
+```
+<!-- END_STEP -->
+
+When you run the apps with the `ERROR_WORKFLOW_MODE` environment variable set, you will see output like this:
+```
+...
+app2 - received workflow call
+app2 - raising error in workflow due to error mode being enabled
+app1 - received workflow error from app2
+...
+```
+among others. This shows that the workflow calls are failing as expected, and they are being handled as expected too.
+

examples/workflow/cross-app1.py

@@ -10,6 +10,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from datetime import timedelta
+
+from durabletask.task import TaskFailedError
 import dapr.ext.workflow as wf
 import time
 
@@ -21,14 +24,23 @@ def app1_workflow(ctx: wf.DaprWorkflowContext):
     print(f'app1 - received workflow call', flush=True)
     print(f'app1 - triggering app2 workflow', flush=True)
 
-    yield ctx.call_child_workflow(
-        workflow='app2_workflow',
-        input=None,
-        app_id='wfexample2',
-    )
-    print(f'app1 - received workflow result', flush=True)
-    print(f'app1 - returning workflow result', flush=True)
+    try:
+        retry_policy = wf.RetryPolicy(
+            max_number_of_attempts=2,
+            first_retry_interval=timedelta(milliseconds=100),
+            max_retry_interval=timedelta(seconds=3),
+        )
+        yield ctx.call_child_workflow(
+            workflow='app2_workflow',
+            input=None,
+            app_id='wfexample2',
+            retry_policy=retry_policy,
+        )
+        print(f'app1 - received workflow result', flush=True)
+    except TaskFailedError as e:
+        print(f'app1 - received workflow error from app2', flush=True)
 
+    print(f'app1 - returning workflow result', flush=True)
     return 1
 
 
@@ -41,6 +53,6 @@ def app1_workflow(ctx: wf.DaprWorkflowContext):
     instance_id = wf_client.schedule_new_workflow(workflow=app1_workflow)
 
     # Wait for the workflow to complete
-    time.sleep(5)
+    time.sleep(7)
 
     wfr.shutdown()

examples/workflow/cross-app2.py

@@ -10,6 +10,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from datetime import timedelta
+import os
+
+from durabletask.task import TaskFailedError
 import dapr.ext.workflow as wf
 import time
 
@@ -19,11 +23,24 @@
 @wfr.workflow
 def app2_workflow(ctx: wf.DaprWorkflowContext):
     print(f'app2 - received workflow call', flush=True)
+    if os.getenv('ERROR_WORKFLOW_MODE', 'false') == 'true':
+        print(f'app2 - raising error in workflow due to error mode being enabled', flush=True)
+        raise ValueError('Error in workflow due to error mode being enabled')
     print(f'app2 - triggering app3 activity', flush=True)
-    yield ctx.call_activity('app3_activity', input=None, app_id='wfexample3')
-    print(f'app2 - received activity result', flush=True)
-    print(f'app2 - returning workflow result', flush=True)
+    try:
+        retry_policy = wf.RetryPolicy(
+            max_number_of_attempts=2,
+            first_retry_interval=timedelta(milliseconds=100),
+            max_retry_interval=timedelta(seconds=3),
+        )
+        result = yield ctx.call_activity(
+            'app3_activity', input=None, app_id='wfexample3', retry_policy=retry_policy
+        )
+        print(f'app2 - received activity result', flush=True)
+    except TaskFailedError as e:
+        print(f'app2 - received activity error from app3', flush=True)
 
+    print(f'app2 - returning workflow result', flush=True)
     return 2
 
 

examples/workflow/cross-app3.py

@@ -9,7 +9,7 @@
 # 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.
-
+import os
 import dapr.ext.workflow as wf
 import time
 
@@ -19,6 +19,9 @@
 @wfr.activity
 def app3_activity(ctx: wf.DaprWorkflowContext) -> int:
     print(f'app3 - received activity call', flush=True)
+    if os.getenv('ERROR_ACTIVITY_MODE', 'false') == 'true':
+        print(f'app3 - raising error in activity due to error mode being enabled', flush=True)
+        raise ValueError('Error in activity due to error mode being enabled')
     print(f'app3 - returning activity result', flush=True)
     return 3