Assure that when something goes wrong calling a service task that we get as much good information about the problem as possible.

spiffworkflow-backend/src/spiffworkflow_backend/services/service_task_service.py

@@ -7,6 +7,7 @@ import sentry_sdk
 from flask import current_app
 from flask import g
 
+from spiffworkflow_backend.exceptions.api_error import ApiError
 from spiffworkflow_backend.services.file_system_service import FileSystemService
 from spiffworkflow_backend.services.secret_service import SecretService
 from spiffworkflow_backend.services.user_service import UserService
@@ -43,6 +44,28 @@ class ServiceTaskDelegate:
 
         return value
 
+    @staticmethod
+    def get_message_for_status(code):
+        """Given a code like 404, return a string like 'The requested resource was not found.'"""
+        msg = f'HTTP Status Code {code}.'
+        if code == 301:
+            msg =  '301 (Permanent Redirect) - you may need to use a different URL in this service task.'
+        if code == 302:
+            msg =  '302 (Temporary Redirect) - you may need to use a different URL in this service task.'
+        if code == 400:
+            msg =  '400 (Bad Request) - The request was received by the service, but it was not understood.'
+        if code == 401:
+            msg =  '401 (Unauthorized Error) - this end point requires some form of authentication.'
+        if code == 403:
+            msg =  '403 (Forbidden) - The service you called refused to accept the request.'
+        if code == 404:
+            msg =  '404 (Not Found) - The service did not find the requested resource.'
+        if code == 500:
+            msg =  '500 (Internal Server Error) - The service you called is experiencing technical difficulties.'
+        if code == 501:
+            msg =  '501 (Not Implemented) - This service needs to be called with the different method (like POST not GET).'
+        return msg
+
     @staticmethod
     def call_connector(name: str, bpmn_params: Any, task_data: Any) -> str:
         """Calls a connector via the configured proxy."""
@@ -55,20 +78,40 @@ class ServiceTaskDelegate:
             params["spiff__task_data"] = task_data
 
             proxied_response = requests.post(call_url, json=params)
+            response_text = proxied_response.text
+            json_parse_error = None
 
-            parsed_response = json.loads(proxied_response.text)
+            if response_text == "":
+                response_text = "{}"
+            try:
+                parsed_response = json.loads(response_text)
+            except Exception as e:
+                json_parse_error = e
+                parsed_response = {}
+
+            if proxied_response.status_code >= 300:
+                error = f"Received an unexpected response from the service : "
+                error += ServiceTaskDelegate.get_message_for_status(proxied_response.status_code)
+                if "error" in parsed_response:
+                    error += parsed_response["error"]
+                if json_parse_error:
+                    error += "A critical component (The connector proxy) is not responding correctly."
+                raise ConnectorProxyError(error)
+            elif json_parse_error:
+                raise ConnectorProxyError( f"There is a problem with this connector: '{name}'. "
+                                           f"Responses for connectors must be in JSON format. ")
 
             if "refreshed_token_set" not in parsed_response:
-                return proxied_response.text
+                return response_text
 
             secret_key = parsed_response["auth"]
             refreshed_token_set = json.dumps(parsed_response["refreshed_token_set"])
             user_id = g.user.id if UserService.has_user() else None
             SecretService().update_secret(secret_key, refreshed_token_set, user_id)
-
             return json.dumps(parsed_response["api_response"])
 
 
+
 class ServiceTaskService:
     """ServiceTaskService."""
 

spiffworkflow-backend/tests/spiffworkflow_backend/unit/test_service_task_delegate.py

@@ -1,9 +1,10 @@
 """Test_various_bpmn_constructs."""
+import pytest
 from flask.app import Flask
 from tests.spiffworkflow_backend.helpers.base_test import BaseTest
 
 from spiffworkflow_backend.services.secret_service import SecretService
-from spiffworkflow_backend.services.service_task_service import ServiceTaskDelegate
+from spiffworkflow_backend.services.service_task_service import ServiceTaskDelegate, ConnectorProxyError
 
 
 class TestServiceTaskDelegate(BaseTest):
@@ -31,3 +32,12 @@ class TestServiceTaskDelegate(BaseTest):
         SecretService().add_secret("hot_secret", "my_secret_value", user.id)
         result = ServiceTaskDelegate.check_prefixes("secret:hot_secret")
         assert result == "my_secret_value"
+
+    def test_invalid_call_returns_good_error_message(
+        self, app: Flask, with_db_and_bpmn_file_cleanup: None
+    ) -> None:
+        with pytest.raises(ConnectorProxyError) as ae:
+            ServiceTaskDelegate.call_connector('my_invalid_operation', {}, {})
+        assert "404" in str(ae)
+        assert "The service did not find the requested resource." in str(ae)
+        assert "A critical component (The connector proxy) is not responding correctly." in str(ae)