Add no debug mode flag. (hedyorg#817)

CONTRIBUTING.md

@@ -34,6 +34,12 @@ you can wrap the command in a loop to restart the server quickly).
 (.env)$ while true; do env FLASK_ENV=development python app.py; sleep 1; done
 ```
 
+If you prefer to avoid development mode (which might make the app reloads slower when opening Hedy in the browser), pass the `NO_DEBUG_MODE` environment variable.
+
+```bash
+(.env)$ env NO_DEBUG_MODE=1 python app.py
+```
+
 If you want to run the website locally, but would prefer to use Docker instead of installing python, you can build a container image and run it like so:
 
 ```bash

app.py

@@ -464,7 +464,7 @@ def get_quiz(level_source, question_nr, attempt):
 
         # Loop through the questions and check that the loop doesn't reach out of bounds
         q_nr = int(question_nr)
-        
+
         if int(attempt) == 1:
             questionStatus = 'start'
 
@@ -1104,7 +1104,7 @@ def on_server_start():
     # Start the server on a developer machine. Flask is initialized in DEBUG mode, so it
     # hot-reloads files. We also flip our own internal "debug mode" flag to True, so our
     # own file loading routines also hot-reload.
-    utils.set_debug_mode(True)
+    utils.set_debug_mode(not os.getenv ('NO_DEBUG_MODE'))
 
     # If we are running in a Python debugger, don't use flasks reload mode. It creates
     # subprocesses which make debugging harder.
@@ -1115,4 +1115,4 @@ def on_server_start():
     # Threaded option enables multiple instances for multiple user access support
     app.run(threaded=True, debug=not is_in_debugger, port=config ['port'], host="0.0.0.0")
 
-    # See `Procfile` for how the server is started on Heroku.
+    # See `Procfile` for how the server is started on Heroku.

doc/CONFIGURATION.md

@@ -63,6 +63,12 @@ To set up the port of the app through an env variable (helpful to start multiple
 PORT
 ```
 
+To turn off development mode
+
+```
+NO_DEBUG_MODE
+```
+
 ## Heroku Metadata
 
 This app depends on some environment variables that require Heroku dyno metadata.