fix local development with the Pub/Sub emulator

src/functions_framework/__init__.py

@@ -126,7 +126,7 @@ def view_func(path):
             function(data, context)
         else:
             # This is a regular CloudEvent
-            event_data = request.get_json()
+            event_data = event_conversion.marshal_background_event_data(request)
             if not event_data:
                 flask.abort(400)
             event_object = BackgroundEvent(**event_data)

src/functions_framework/event_conversion.py

@@ -13,7 +13,8 @@
 # limitations under the License.
 import re
 
-from typing import Tuple
+from datetime import datetime
+from typing import Optional, Tuple
 
 from cloudevents.http import CloudEvent
 
@@ -55,6 +56,12 @@
 _PUBSUB_CE_SERVICE = "pubsub.googleapis.com"
 _STORAGE_CE_SERVICE = "storage.googleapis.com"
 
+# Raw pubsub types
+_PUBSUB_EVENT_TYPE = "google.pubsub.topic.publish"
+_PUBSUB_MESSAGE_TYPE = "type.googleapis.com/google.pubsub.v1.PubsubMessage"
+
+_PUBSUB_TOPIC_REQUEST_PATH = re.compile(r"projects\/[^/?]+\/topics\/[^/?]+")
+
 # Maps background event services to their equivalent CloudEvent services.
 _SERVICE_BACKGROUND_TO_CE = {
     "providers/cloud.firestore/": _FIRESTORE_CE_SERVICE,
@@ -89,8 +96,8 @@
 
 
 def background_event_to_cloudevent(request) -> CloudEvent:
-    """Converts a background event represented by the given HTTP request into a CloudEvent. """
-    event_data = request.get_json()
+    """Converts a background event represented by the given HTTP request into a CloudEvent."""
+    event_data = marshal_background_event_data(request)
     if not event_data:
         raise EventConversionException("Failed to parse JSON")
 
@@ -168,3 +175,56 @@ def _split_resource(context: Context) -> Tuple[str, str, str]:
         raise EventConversionException("Resource regex did not match")
 
     return service, match.group(1), match.group(2)
+
+
+def marshal_background_event_data(request):
+    """Marshal the request body of a raw Pub/Sub HTTP request into the schema that is expected of
+    a background event"""
+    try:
+        request_data = request.get_json()
+        if not _is_raw_pubsub_payload(request_data):
+            # If this in not a raw Pub/Sub request, return the unaltered request data.
+            return request_data
+        return {
+            "context": {
+                "eventId": request_data["message"]["messageId"],
+                "timestamp": request_data["message"].get(
+                    "publishTime", datetime.utcnow().isoformat() + "Z"
+                ),
+                "eventType": _PUBSUB_EVENT_TYPE,
+                "resource": {
+                    "service": _PUBSUB_CE_SERVICE,
+                    "type": _PUBSUB_MESSAGE_TYPE,
+                    "name": _parse_pubsub_topic(request.path),
+                },
+            },
+            "data": {
+                "@type": _PUBSUB_MESSAGE_TYPE,
+                "data": request_data["message"]["data"],
+                "attributes": request_data["message"]["attributes"],
+            },
+        }
+    except (AttributeError, KeyError, TypeError):
+        raise EventConversionException("Failed to convert Pub/Sub payload to event")
+
+
+def _is_raw_pubsub_payload(request_data) -> bool:
+    """Does the given request body match the schema of a unmarshalled Pub/Sub request"""
+    return (
+        request_data is not None
+        and "context" not in request_data
+        and "subscription" in request_data
+        and "message" in request_data
+        and "data" in request_data["message"]
+        and "messageId" in request_data["message"]
+    )
+
+
+def _parse_pubsub_topic(request_path) -> Optional[str]:
+    match = _PUBSUB_TOPIC_REQUEST_PATH.search(request_path)
+    if match:
+        return match.group(0)
+    else:
+        # It is possible to configure a Pub/Sub subscription to push directly to this function
+        # without passing the topic name in the URL path.
+        return ""

tests/test_convert.py

@@ -65,23 +65,64 @@
 
 BACKGROUND_RESOURCE_STRING = "projects/_/buckets/some-bucket/objects/folder/Test.cs"
 
+PUBSUB_CLOUD_EVENT = {
+    "specversion": "1.0",
+    "id": "1215011316659232",
+    "source": "//pubsub.googleapis.com/projects/sample-project/topics/gcf-test",
+    "time": "2020-05-18T12:13:19Z",
+    "type": "google.cloud.pubsub.topic.v1.messagePublished",
+    "datacontenttype": "application/json",
+    "data": {
+        "message": {
+            "data": "10",
+        },
+    },
+}
+
 
 @pytest.fixture
 def pubsub_cloudevent_output():
-    event = {
-        "specversion": "1.0",
-        "id": "1215011316659232",
-        "source": "//pubsub.googleapis.com/projects/sample-project/topics/gcf-test",
-        "time": "2020-05-18T12:13:19Z",
-        "type": "google.cloud.pubsub.topic.v1.messagePublished",
-        "datacontenttype": "application/json",
+    return from_json(json.dumps(PUBSUB_CLOUD_EVENT))
+
+
+@pytest.fixture
+def raw_pubsub_request():
+    return {
+        "subscription": "projects/sample-project/subscriptions/gcf-test-sub",
+        "message": {
+            "data": "eyJmb28iOiJiYXIifQ==",
+            "messageId": "1215011316659232",
+            "attributes": {"test": "123"},
+        },
+    }
+
+
+@pytest.fixture
+def marshalled_pubsub_request():
+    return {
         "data": {
-            "message": {
-                "data": "10",
+            "@type": "type.googleapis.com/google.pubsub.v1.PubsubMessage",
+            "data": "eyJmb28iOiJiYXIifQ==",
+            "attributes": {"test": "123"},
+        },
+        "context": {
+            "eventId": "1215011316659232",
+            "eventType": "google.pubsub.topic.publish",
+            "resource": {
+                "name": "projects/sample-project/topics/gcf-test",
+                "service": "pubsub.googleapis.com",
+                "type": "type.googleapis.com/google.pubsub.v1.PubsubMessage",
             },
+            "timestamp": "2021-04-17T07:21:18.249Z",
         },
     }
 
+
+@pytest.fixture
+def raw_pubsub_cloudevent_output(marshalled_pubsub_request):
+    event = PUBSUB_CLOUD_EVENT.copy()
+    # the data payload is more complex for the raw pubsub request
+    event["data"] = {"message": marshalled_pubsub_request["data"]}
     return from_json(json.dumps(event))
 
 
@@ -212,3 +253,79 @@ def test_split_resource_no_resource_regex_match():
     with pytest.raises(EventConversionException) as exc_info:
         event_conversion._split_resource(context)
     assert "Resource regex did not match" in exc_info.value.args[0]
+
+
+def test_marshal_background_event_data_without_topic_in_path(
+    raw_pubsub_request, marshalled_pubsub_request
+):
+    req = flask.Request.from_values(json=raw_pubsub_request, path="/myfunc/")
+    payload = event_conversion.marshal_background_event_data(req)
+
+    # Remove timestamps as they get generates on the fly
+    del marshalled_pubsub_request["context"]["timestamp"]
+    del payload["context"]["timestamp"]
+
+    # Resource name is set to empty string when it cannot be parsed from the request path
+    marshalled_pubsub_request["context"]["resource"]["name"] = ""
+
+    assert payload == marshalled_pubsub_request
+
+
+def test_marshal_background_event_data_with_topic_path(
+    raw_pubsub_request, marshalled_pubsub_request
+):
+    req = flask.Request.from_values(
+        json=raw_pubsub_request,
+        path="x/projects/sample-project/topics/gcf-test?pubsub_trigger=true",
+    )
+    payload = event_conversion.marshal_background_event_data(req)
+
+    # Remove timestamps as they are generated on the fly.
+    del marshalled_pubsub_request["context"]["timestamp"]
+    del payload["context"]["timestamp"]
+
+    assert payload == marshalled_pubsub_request
+
+
+def test_pubsub_emulator_request_to_cloudevent(
+    raw_pubsub_request, raw_pubsub_cloudevent_output
+):
+    req = flask.Request.from_values(
+        json=raw_pubsub_request,
+        path="x/projects/sample-project/topics/gcf-test?pubsub_trigger=true",
+    )
+    cloudevent = event_conversion.background_event_to_cloudevent(req)
+
+    # Remove timestamps as they are generated on the fly.
+    del raw_pubsub_cloudevent_output["time"]
+    del cloudevent["time"]
+
+    assert cloudevent == raw_pubsub_cloudevent_output
+
+
+def test_pubsub_emulator_request_to_cloudevent_without_topic_path(
+    raw_pubsub_request, raw_pubsub_cloudevent_output
+):
+    req = flask.Request.from_values(json=raw_pubsub_request, path="/")
+    cloudevent = event_conversion.background_event_to_cloudevent(req)
+
+    # Remove timestamps as they are generated on the fly.
+    del raw_pubsub_cloudevent_output["time"]
+    del cloudevent["time"]
+
+    # Default to the service name, when the topic is not configured subscription's pushEndpoint.
+    raw_pubsub_cloudevent_output["source"] = "//pubsub.googleapis.com/"
+
+    assert cloudevent == raw_pubsub_cloudevent_output
+
+
+def test_pubsub_emulator_request_with_invalid_message(
+    raw_pubsub_request, raw_pubsub_cloudevent_output
+):
+    # Create an invalid message payload
+    raw_pubsub_request["message"] = None
+    req = flask.Request.from_values(json=raw_pubsub_request, path="/")
+
+    with pytest.raises(EventConversionException) as exc_info:
+        cloudevent = event_conversion.background_event_to_cloudevent(req)
+    assert "Failed to convert Pub/Sub payload to event" in exc_info.value.args[0]