Add example of graceful shutdown

Author: Bacto

Makefile

@@ -1,2 +1,4 @@
 run:
-	gunicorn app:app -b 0.0.0.0:8080
+	gunicorn app:app \
+		--error-logfile - \
+		-b 0.0.0.0:8080

app.py

@@ -1,7 +1,36 @@
+import signal, os, sys
+import time
 from flask import Flask
 app = Flask(__name__)
 
 # Define route "/" named "index"
 @app.route('/')
 def index():
-  return '🎉 Congratulations! Your first Python3 application is running on Stackhero!'
+  return '🎉 Congratulations! Your first Python3 application is running on Stackhero!'
+
+
+# You'll see this log directly on your Stackhero's console
+print('🎉 The app has just start!')
+
+
+# Handle termination signal
+# When you will push your new code to Stackhero, we will send a termination signal (SIGTERM) to your running app.
+# The goal here is to let your app closing connections properly, like connections to databases etc...
+sigtermHandled = False
+def sigtermHandler(signum, frame):
+  # Avoid to execute multiple time this function
+  global sigtermHandled
+  if sigtermHandled == True:
+    return
+  sigtermHandled = True
+
+  # You'll see this log directly on your Stackhero's console
+  print('😯 SIGTERM signal received')
+
+  # You can close your database connection and do other cleanup here
+  # dbConnection.close()
+
+  # Finally exit the process
+  sys.exit(0)
+
+signal.signal(signal.SIGTERM, sigtermHandler)