def _split_resource(context: Context) -> Tuple[str, str, str]:
"""Splits a background event's resource into a CloudEvent service, resource, and subject."""
service = ""
resource = ""
if isinstance(context.resource, dict):
service = context.resource.get("service", "")
resource = context.resource["name"]
else:
resource = context.resource
# If there's no service we'll choose an appropriate one based on the event type.
if not service:
for b_service, ce_service in _SERVICE_BACKGROUND_TO_CE.items():
if context.event_type.startswith(b_service):
service = ce_service
break
if not service:
raise EventConversionException(
"Unable to find CloudEvent equivalent service "
f"for {context.event_type}")
# If we don't need to split the resource string then we're done.
if service not in _CE_SERVICE_TO_RESOURCE_RE:
return service, resource, ""
# Split resource into resource and subject.
match = _CE_SERVICE_TO_RESOURCE_RE[service].fullmatch(resource)
if not match:
raise EventConversionException("Resource regex did not match")
return service, match.group(1), match.group(2)
def cloud_event_to_background_event(request) -> Tuple[Any, Context]:
"""Converts a background event represented by the given HTTP request into a CloudEvent."""
try:
event = from_http(request.headers, request.get_data())
data = event.data
service, name = _split_ce_source(event["source"])
if event["type"] not in _CE_TO_BACKGROUND_TYPE:
raise EventConversionException(
f'Unable to find background event equivalent type for "{event["type"]}"'
)
if service == _PUBSUB_CE_SERVICE:
resource = {
"service": service,
"name": name,
"type": _PUBSUB_MESSAGE_TYPE
}
if "message" in data:
data = data["message"]
if "messageId" in data:
del data["messageId"]
if "publishTime" in data:
del data["publishTime"]
elif service == _FIREBASE_AUTH_CE_SERVICE:
resource = name
if "metadata" in data:
for old, new in _FIREBASE_AUTH_METADATA_FIELDS_CE_TO_BACKGROUND.items(
):
if old in data["metadata"]:
data["metadata"][new] = data["metadata"][old]
del data["metadata"][old]
elif service == _STORAGE_CE_SERVICE:
resource = {
"name": f"{name}/{event['subject']}",
"service": service,
"type": data["kind"],
}
elif service == _FIREBASE_DB_CE_SERVICE:
name = re.sub("/locations/[^/]+", "", name)
resource = f"{name}/{event['subject']}"
else:
resource = f"{name}/{event['subject']}"
context = Context(
eventId=event["id"],
timestamp=event["time"],
eventType=_CE_TO_BACKGROUND_TYPE[event["type"]],
resource=resource,
)
return (data, context)
except (AttributeError, KeyError, TypeError, MissingRequiredFields):
raise EventConversionException(
"Failed to convert CloudEvent to BackgroundEvent.")
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 background_event_to_cloudevent(request) -> CloudEvent:
"""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")
event_object = BackgroundEvent(**event_data)
data = event_object.data
context = Context(**event_object.context)
if context.event_type not in _BACKGROUND_TO_CE_TYPE:
raise EventConversionException(
f'Unable to find CloudEvent equivalent type for "{context.event_type}"'
)
new_type = _BACKGROUND_TO_CE_TYPE[context.event_type]
service, resource, subject = _split_resource(context)
# Handle Pub/Sub events.
if service == _PUBSUB_CE_SERVICE:
data = {"message": data}
# Handle Firebase Auth events.
if service == _FIREBASE_AUTH_CE_SERVICE:
if "metadata" in data:
for old, new in _FIREBASE_AUTH_METADATA_FIELDS_BACKGROUND_TO_CE.items(
):
if old in data["metadata"]:
data["metadata"][new] = data["metadata"][old]
del data["metadata"][old]
if "uid" in data:
uid = data["uid"]
subject = f"users/{uid}"
metadata = {
"id": context.event_id,
"time": context.timestamp,
"specversion": _CLOUDEVENT_SPEC_VERSION,
"datacontenttype": "application/json",
"type": new_type,
"source": f"//{service}/{resource}",
}
if subject:
metadata["subject"] = subject
return CloudEvent(metadata, data)
def _split_ce_source(source) -> Tuple[str, str]:
"""Splits a CloudEvent source string into resource and subject components."""
regex = re.compile(r"\/\/([^/]+)\/(.+)")
match = regex.fullmatch(source)
if not match:
raise EventConversionException("Unexpected CloudEvent source.")
return match.group(1), match.group(2)
def background_event_to_cloud_event(request) -> CloudEvent:
"""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")
event_object = BackgroundEvent(**event_data)
data = event_object.data
context = Context(**event_object.context)
if context.event_type not in _BACKGROUND_TO_CE_TYPE:
raise EventConversionException(
f'Unable to find CloudEvent equivalent type for "{context.event_type}"'
)
new_type = _BACKGROUND_TO_CE_TYPE[context.event_type]
service, resource, subject = _split_resource(context)
source = f"//{service}/{resource}"
# Handle Pub/Sub events.
if service == _PUBSUB_CE_SERVICE:
if "messageId" not in data:
data["messageId"] = context.event_id
if "publishTime" not in data:
data["publishTime"] = context.timestamp
data = {"message": data}
# Handle Firebase Auth events.
if service == _FIREBASE_AUTH_CE_SERVICE:
if "metadata" in data:
for old, new in _FIREBASE_AUTH_METADATA_FIELDS_BACKGROUND_TO_CE.items(
):
if old in data["metadata"]:
data["metadata"][new] = data["metadata"][old]
del data["metadata"][old]
if "uid" in data:
uid = data["uid"]
subject = f"users/{uid}"
# Handle Firebase DB events.
if service == _FIREBASE_DB_CE_SERVICE:
# The CE source of firebasedatabase CloudEvents includes location information
# that is inferred from the 'domain' field of legacy events.
if "domain" not in event_data:
raise EventConversionException(
"Invalid FirebaseDB event payload: missing 'domain'")
domain = event_data["domain"]
location = "us-central1"
if domain != "firebaseio.com":
location = domain.split(".")[0]
resource = f"projects/_/locations/{location}/{resource}"
source = f"//{service}/{resource}"
metadata = {
"id": context.event_id,
"time": context.timestamp,
"specversion": _CLOUD_EVENT_SPEC_VERSION,
"datacontenttype": "application/json",
"type": new_type,
"source": source,
}
if subject:
metadata["subject"] = subject
return CloudEvent(metadata, data)