Added port via env

app/app.py

@@ -64,4 +64,5 @@ def index():
     )
 
 if __name__ == "__main__":
-    app.run(debug=(FLASK_ENV == "development"), host="0.0.0.0", port=5000)
+    port = int(os.getenv("PORT", 5000))
+    app.run(debug=(FLASK_ENV == "development"), host="0.0.0.0", port=port)