Did you test this? it seems broken.
settings.MQTT_USE_SSL is a bool already.

Please remove the strtobool() method and document it as being optional and taking True/False values.

You seem to be mixing up self-signed certs and client certs.
This seems to be for using client certs.

If the server is self-signed then in theory you could pass in something to the loop.create_connection() but qmqtt doesn't support it (and it's not worth having IMHO).

Yes, I meant self-signed certs on the server. I'll amend the comment appropriately.

remove strtobool()

There is a valid use case and a story behind this...

The use case

.env file

# deployment specific secrets and settings
# --- snip ---

# mqtt settings
# host, username, password, etc
# including...
MQTT_PORT=8883
MQTT_USE_SSL=True
MQTT_SSL_VERIFY=True

My django settings.py file

# other includes
# --- snip ---

from dotenv import load_dotenv
load_dotenv()
env = os.environ

# --- snip ---
# standard django settings.py stuff
# --- snip ---

MQTT_PORT=env.get('MQTT_PORT', None)
MQTT_USE_SSL=env.get('MQTT_USE_SSL', None)
MQTT_SSL_VERIFY=env.get('MQTT_SSL_VERIFY', None)

By the time they reach channelsmqttproxy.py:

type(settings.MQTT_PORT) = <class 'str'>
type(settings.MQTT_USE_SSL) = <class 'str'>
type(settings.MQTT_SSL_VERIFY) = <class 'str'>

The story

Now, the obvious stuff

int(2) = 2
int('2') = 2
bool(True) = True
bool('True') = True
bool(False) = False

but, here's the thing that got me...

bool('False') = True # Makes sense when you stop and think about it but doesn't seem intuitive for this case

Proposal

Above these blocks with the strtobool() calls, there is already a call to int() to ensure MQTT_PORT is an int or can be converted to an int.
Given that there is already protection for MQTT_PORT, I would like to include the same for MQTT_USE_SSL and MQTT_SSL_VERIFY.

Having said all that, I would like to

• Rename strtobool() to tobool() to be closer to its intent.
• Have tobool() behave in the same manner as int() would i.e.

tobool(True) = True
tobool('True') = True
tobool(False) = False
tobool('False') = False # Fixed for intent

Please let me know if you are happy with that and I will proceed with the changes.

Oh, and I'll remember to run it through the linter this time too.

I see the issue - however I think the settings.py should be documented as taking bool.
The solution would be to have this in settings.py:

   from mysettings.helper import tobool
   
    MQTT_USE_SSL = tobool(env.get('MQTT_USE_SSL', None))

Doesn't that make more sense?