Add health-check server (RemiRigal#21)

* Add health-check server

Dockerfile

@@ -3,6 +3,9 @@ FROM python:3.8-alpine
 ENV LANG C.UTF-8
 ENV LC_ALL C.UTF-8
 
+RUN apk add --update curl && \
+    rm -rf /var/cache/apk/*
+
 COPY ./requirements.txt /app/requirements.txt
 
 RUN python3 -m pip install --no-cache-dir -r /app/requirements.txt
@@ -13,4 +16,6 @@ WORKDIR /app
 
 VOLUME /config
 
+HEALTHCHECK CMD curl --fail http://localhost/ || exit 1
+
 ENTRYPOINT ["python3", "main.py", "-c", "/config/config.yaml"]

main.py

@@ -13,14 +13,17 @@
 from utils.scheduler import Scheduler
 from utils.configuration import Configuration
 from utils.plex import PlexUtils
+from utils.healthcheck import HealthcheckServer
 
 
 class PlexAutoLanguages(object):
 
     def __init__(self, user_config_path: str):
         self.alive = False
-        self.set_signal_handlers()
         self.notifier = None
+        self.set_signal_handlers()
+        self.healthcheck_server = HealthcheckServer("Plex-Auto-Languages", self.is_ready, self.is_healthy)
+        self.healthcheck_server.start()
         self.config = Configuration(user_config_path)
         # Plex
         self.plex = PlexServer(self.config.get("plex.url"), self.config.get("plex.token"))
@@ -48,6 +51,12 @@ def get_plex_user_id(self):
         logger.error("Unable to find the user id associated with the provided Plex Token")
         sys.exit(0)
 
+    def is_ready(self):
+        return self.alive
+
+    def is_healthy(self):
+        return self.alive and self.notifier is not None and self.notifier.is_alive()
+
     def set_signal_handlers(self):
         signal.signal(signal.SIGINT, self.stop)
         signal.signal(signal.SIGTERM, self.stop)
@@ -69,6 +78,7 @@ def start(self):
             logger.info("Stopping scheduler")
             self.scheduler.stop_event.set()
         logger.info("Stopping alert listener")
+        self.healthcheck_server.shutdown()
 
     def alert_listener_callback(self, message: dict):
         if self.config.get("trigger_on_play") and message["type"] == "playing":

requirements.txt

@@ -3,3 +3,4 @@ websocket-client>=1.3.1
 apprise>=0.9.8
 PyYAML>=6.0
 schedule>=1.1.0
+Flask>=2.0.3

utils/healthcheck.py

@@ -0,0 +1,41 @@
+import json
+import logging
+from flask import Flask
+from typing import Callable
+from threading import Thread
+from werkzeug.serving import make_server
+
+
+flask_logger = logging.getLogger("werkzeug")
+flask_logger.setLevel(logging.ERROR)
+
+
+class HealthcheckServer(Thread):
+
+    def __init__(self, name: str, is_ready: Callable, is_healthy: Callable):
+        super(HealthcheckServer, self).__init__()
+        self._is_healthy = is_healthy
+        self._is_ready = is_ready
+        self._app = Flask(name)
+        self._server = make_server("0.0.0.0", 80, self._app)
+        self._ctx = self._app.app_context()
+        self._ctx.push()
+
+        @self._app.route("/")
+        @self._app.route("/health")
+        def __health():
+            healthy = self._is_healthy()
+            code = 200 if healthy else 400
+            return json.dumps({"healthy": healthy}), code
+
+        @self._app.route("/ready")
+        def __ready():
+            ready = self._is_ready()
+            code = 200 if ready else 400
+            return json.dumps({"ready": ready}), code
+
+    def run(self):
+        self._server.serve_forever()
+
+    def shutdown(self):
+        self._server.shutdown()