Add passive Flask-based sensor that echoes input

contrib/examples/sensors/echo_flask_app.py

@@ -0,0 +1,49 @@
+from flask import request, Flask
+
+from st2reactor.sensor.base import Sensor
+
+
+class EchoFlaskSensor(Sensor):
+
+    def __init__(self, sensor_service, config):
+        super(EchoFlaskSensor, self).__init__(
+            sensor_service=sensor_service,
+            config=config
+        )
+
+        self._host = '127.0.0.1'
+        self._port = '5000'
+        self._path = '/echo'
+
+        self._log = self._sensor_service.get_logger(__name__)
+        self._app = Flask(__name__)
+
+    def setup(self):
+        pass
+
+    def run(self):
+        @self._app.route(self._path, methods=['POST'])
+        def echo():
+            payload = request.get_json(force=True)
+            self._sensor_service.dispatch(trigger="examples.echo_flask",
+                                          payload=payload)
+            return request.data
+
+        self._log.info('Listening for payload on http://%s:%s%s' %
+                       (self._host, self._port, self._path))
+        self._app.run(host=self._host, port=self._port, threaded=True)
+
+    def cleanup(self):
+        pass
+
+    def add_trigger(self, trigger):
+        # This method is called when trigger is created
+        pass
+
+    def update_trigger(self, trigger):
+        # This method is called when trigger is updated
+        pass
+
+    def remove_trigger(self, trigger):
+        # This method is called when trigger is deleted
+        pass

contrib/examples/sensors/echo_flask_app.yaml

@@ -0,0 +1,13 @@
+---
+  class_name: "EchoFlaskSensor"
+  entry_point: "echo_flask_app.py"
+  description: "Simple echo flask app sensor that echoes its input."
+  trigger_types:
+    -
+      name: "echoflasksensor"
+      description: "Echo flask sensor."
+      payload_schema:
+        type: "object"
+        properties:
+          payload:
+            type: "object"