Implemented synchronization with webhook responses.

When a client triggers a `WebhookEvent` by calling a configured webhook
over `/hook/<hook_name>`, the server will now wait for the configured
`@hook` function to complete and it will return the returned response
back to the client.

This makes webhooks much more powerful, as they can be used to proxy
HTTP calls or other services, and in general return something to the
client instead of just executing actions.

platypush/backend/http/app/routes/hook.py

@@ -1,9 +1,11 @@
 import json
 
-from flask import Blueprint, abort, request, Response
+from flask import Blueprint, abort, request
+from flask.wrappers import Response
 
 from platypush.backend.http.app import template_folder
 from platypush.backend.http.app.utils import logger, send_message
+from platypush.config import Config
 from platypush.message.event.http.hook import WebhookEvent
 
 
@@ -15,9 +17,11 @@ __routes__ = [
 ]
 
 
-@hook.route('/hook/<hook_name>', methods=['GET', 'POST', 'PUT', 'DELETE', 'PATCH', 'OPTIONS'])
+@hook.route(
-def _hook(hook_name):
+    '/hook/<hook_name>', methods=['GET', 'POST', 'PUT', 'DELETE', 'PATCH', 'OPTIONS']
-    """ Endpoint for custom webhooks """
+)
+def hook_route(hook_name):
+    """Endpoint for custom webhooks"""
 
     event_args = {
         'hook': hook_name,
@@ -28,20 +32,36 @@ def _hook(hook_name):
     }
 
     if event_args['data']:
-        # noinspection PyBroadException
         try:
             event_args['data'] = json.loads(event_args['data'])
         except Exception as e:
-            logger().warning('Not a valid JSON string: {}: {}'.format(event_args['data'], str(e)))
+            logger().warning(
+                'Not a valid JSON string: %s: %s', event_args['data'], str(e)
+            )
 
     event = WebhookEvent(**event_args)
+    matching_hooks = [
+        hook
+        for hook in Config.get_event_hooks().values()
+        if hook.condition.type == WebhookEvent
+        and hook.condition.args.get('hook') == hook_name
+        and request.method.lower()
+        == hook.condition.args.get('method', request.method).lower()
+    ]
 
     try:
         send_message(event)
-        return Response(json.dumps({'status': 'ok', **event_args}), mimetype='application/json')
+
+        # If there are matching hooks, wait for their completion before returning
+        if matching_hooks:
+            return event.wait_response(timeout=60)
+
+        return Response(
+            json.dumps({'status': 'ok', **event_args}), mimetype='application/json'
+        )
     except Exception as e:
         logger().exception(e)
-        logger().error('Error while dispatching webhook event {}: {}'.format(event, str(e)))
+        logger().error('Error while dispatching webhook event %s: %s', event, str(e))
         abort(500, str(e))
 
 

platypush/event/hook.py

@@ -15,10 +15,10 @@ logger = logging.getLogger('platypush')
 
 
 def parse(msg):
-    """ Builds a dict given another dictionary or
+    """Builds a dict given another dictionary or
-        a JSON UTF-8 encoded string/bytearray """
+    a JSON UTF-8 encoded string/bytearray"""
 
-    if isinstance(msg, bytes) or isinstance(msg, bytearray):
+    if isinstance(msg, (bytes, bytearray)):
         msg = msg.decode('utf-8')
     if isinstance(msg, str):
         try:
@@ -30,8 +30,8 @@ def parse(msg):
     return msg
 
 
-class EventCondition(object):
+class EventCondition:
-    """ Event hook condition class """
+    """Event hook condition class"""
 
     def __init__(self, type=Event.__class__, priority=None, **kwargs):
         """
@@ -55,8 +55,8 @@ class EventCondition(object):
 
     @classmethod
     def build(cls, rule):
-        """ Builds a rule given either another EventRule, a dictionary or
+        """Builds a rule given either another EventRule, a dictionary or
-            a JSON UTF-8 encoded string/bytearray """
+        a JSON UTF-8 encoded string/bytearray"""
 
         if isinstance(rule, cls):
             return rule
@@ -64,8 +64,7 @@ class EventCondition(object):
             rule = parse(rule)
 
         assert isinstance(rule, dict), f'Not a valid rule: {rule}'
-        type = get_event_class_by_type(
+        type = get_event_class_by_type(rule.pop('type') if 'type' in rule else 'Event')
-            rule.pop('type') if 'type' in rule else 'Event')
 
         args = {}
         for (key, value) in rule.items():
@@ -75,8 +74,8 @@ class EventCondition(object):
 
 
 class EventAction(Request):
-    """ Event hook action class. It is a special type of runnable request
+    """Event hook action class. It is a special type of runnable request
-        whose fields can be configured later depending on the event context """
+    whose fields can be configured later depending on the event context"""
 
     def __init__(self, target=None, action=None, **args):
         if target is None:
@@ -99,16 +98,16 @@ class EventAction(Request):
         return super().build(action)
 
 
-class EventHook(object):
+class EventHook:
-    """ Event hook class. It consists of one conditions and
+    """Event hook class. It consists of one conditions and
-        one or multiple actions to be executed """
+    one or multiple actions to be executed"""
 
     def __init__(self, name, priority=None, condition=None, actions=None):
-        """ Constructor. Takes a name, a EventCondition object and an event action
+        """Constructor. Takes a name, a EventCondition object and an event action
-            procedure as input. It may also have a priority attached
+        procedure as input. It may also have a priority attached
-            as a positive number. If multiple hooks match against an event,
+        as a positive number. If multiple hooks match against an event,
-            only the ones that have either the maximum match score or the
+        only the ones that have either the maximum match score or the
-            maximum pre-configured priority will be run. """
+        maximum pre-configured priority will be run."""
 
         self.name = name
         self.condition = EventCondition.build(condition or {})
@@ -118,8 +117,8 @@ class EventHook(object):
 
     @classmethod
     def build(cls, name, hook):
-        """ Builds a rule given either another EventRule, a dictionary or
+        """Builds a rule given either another EventRule, a dictionary or
-            a JSON UTF-8 encoded string/bytearray """
+        a JSON UTF-8 encoded string/bytearray"""
 
         if isinstance(hook, cls):
             return hook
@@ -146,14 +145,14 @@ class EventHook(object):
         return cls(name=name, condition=condition, actions=actions, priority=priority)
 
     def matches_event(self, event):
-        """ Returns an EventMatchResult object containing the information
+        """Returns an EventMatchResult object containing the information
-            about the match between the event and this hook """
+        about the match between the event and this hook"""
 
         return event.matches_condition(self.condition)
 
     def run(self, event):
-        """ Checks the condition of the hook against a particular event and
+        """Checks the condition of the hook against a particular event and
-            runs the hook actions if the condition is met """
+        runs the hook actions if the condition is met"""
 
         def _thread_func(result):
             set_thread_name('Event-' + self.name)
@@ -163,7 +162,9 @@ class EventHook(object):
 
         if result.is_match:
             logger.info('Running hook {} triggered by an event'.format(self.name))
-            threading.Thread(target=_thread_func, name='Event-' + self.name, args=(result,)).start()
+            threading.Thread(
+                target=_thread_func, name='Event-' + self.name, args=(result,)
+            ).start()
 
 
 def hook(event_type=Event, **condition):
@@ -172,8 +173,14 @@ def hook(event_type=Event, **condition):
         f.condition = EventCondition(type=event_type, **condition)
 
         @wraps(f)
-        def wrapped(*args, **kwargs):
+        def wrapped(event, *args, **kwargs):
-            return exec_wrapper(f, *args, **kwargs)
+            from platypush.message.event.http.hook import WebhookEvent
+
+            response = exec_wrapper(f, event, *args, **kwargs)
+            if isinstance(event, WebhookEvent):
+                event.send_response(response)
+
+            return response
 
         return wrapped
 

platypush/message/event/http/hook.py

@@ -1,11 +1,26 @@
+import json
+import uuid
+
 from platypush.message.event import Event
+from platypush.utils import get_redis
+
 
 class WebhookEvent(Event):
     """
     Event triggered when a custom webhook is called.
     """
 
-    def __init__(self, *argv, hook, method, data=None, args=None, headers=None, **kwargs):
+    def __init__(
+        self,
+        *argv,
+        hook,
+        method,
+        data=None,
+        args=None,
+        headers=None,
+        response=None,
+        **kwargs,
+    ):
         """
         :param hook: Name of the invoked web hook, from http://host:port/hook/<hook>
         :type hook: str
@@ -21,10 +36,35 @@ class WebhookEvent(Event):
 
         :param headers: Request headers
         :type args: dict
-        """
 
-        super().__init__(hook=hook, method=method, data=data, args=args or {},
+        :param response: Response returned by the hook.
-                         headers=headers or {}, *argv, **kwargs)
+        :type args: dict | list | str
+        """
+        # This queue is used to synchronize with the hook and wait for its completion
+        kwargs['response_queue'] = kwargs.get(
+            'response_queue', f'platypush/webhook/{str(uuid.uuid1())}'
+        )
+
+        super().__init__(
+            *argv,
+            hook=hook,
+            method=method,
+            data=data,
+            args=args or {},
+            headers=headers or {},
+            response=response,
+            **kwargs,
+        )
+
+    def send_response(self, response):
+        output = response.output
+        if isinstance(output, (dict, list)):
+            output = json.dumps(output)
+
+        get_redis().rpush(self.args['response_queue'], output)
+
+    def wait_response(self, timeout=None):
+        return get_redis().blpop(self.args['response_queue'], timeout=timeout)[1]
 
 
 # vim:sw=4:ts=4:et: