rename scdf-python-app to polyglot-python-app

dataflow-website/recipes/polyglot/polyglot-python-app/util/actuator.py

@@ -0,0 +1,56 @@
+import sys
+import threading
+
+from flask import Flask, Response
+
+
+class Actuator:
+    """Actuator is used to expose operational information about the running application, such as `health/liveliness`,
+    `info`, `env`, etc. It uses HTTP endpoints to enable us to interact with it.
+
+    The `/actuator/health` and `/actuator/info` handles the Kubernetes liveness and readiness probes requests.
+    Kubernetes expects HTTP 200 status code to consider the application live and ready.
+
+     :param port: the HTTP port used by the Actuator.
+     :param info_content: The text response to be returned by the /actuator/info endpoint.
+     """
+
+    def __init__(self, port=8080, info_content='Info'):
+        self.http_app = Actuator.__create_http_app(info_content)
+        self.port = port
+        print(info_content)
+        sys.stdout.flush()
+
+    def __run(self):
+        self.http_app.run(port=self.port, host='0.0.0.0')
+
+    @staticmethod
+    def __create_http_app(info_description):
+        app = Flask(__name__)
+        app.debug = False
+        app.use_reloader = False
+
+        @app.route('/actuator/health')
+        def health():
+            return Response('Alive', status=200)
+
+        @app.route('/actuator/info')
+        def info():
+            return Response(info_description, status=200, content_type='text/plain')
+
+        return app
+
+    @staticmethod
+    def start(port=8080, info='Info'):
+        """Starts the `Actuator` in a separate thread.
+
+        :param port: the HTTP port used by the Actuator. Defaults to 8080.
+        :param info: The text response to be returned by the /actuator/info endpoint.
+        """
+        try:
+            thread = threading.Thread(target=Actuator(port, info).__run)
+            thread.setDaemon(True)
+            thread.start()
+            print('Actuator started!')
+        except KeyboardInterrupt:
+            sys.exit(0)