Event handlers awkward interaction with the Django `RollbarNotifierMiddleware`

[phillipuniverse]

I am having an issue where it appears the only clean option to initialize Rollbar event handlers (e.g. rollbar.events.add_payload_handler) is within the RollbarNotifierMiddleware as a subclass of __init__. This does work, but it's not very clean.

Here is my ROLLBAR variable in settings.py:

ROLLBAR = {
    'access_token': env.str('ROLLBAR_ACCESS_TOKEN', ''),
    'environment': 'dev',
    'branch': master,
    'root': '/usr/src/app/',
    'enabled': ROLLBAR_ENABLED,
    'locals': {
        'enabled': True,
        'safe_repr': False,
    },
    'ignorable_404_urls': (
        re.compile('.*'),  # never report a 404 to Rollbar
    ),
}

Then at the end of settings.py I want to add a payload handler to add trace information from OpenTelemetry:

import rollbar
from django.conf import settings

def transform_rollbar_payload(
        payload: Dict[str, Any], **kwargs: Dict[str, Any]
) -> Dict[str, Any]:
    data = payload["data"]
    custom = data.get("custom", {})

    custom['service'] = settings.SERVICE
    custom['env'] = settings.ENVIRONMENT
    custom['version'] = settings.VERSION
    span = trace.get_current_span()
    if span != trace.span.INVALID_SPAN:
        ctx = span.get_span_context()
        if ctx != trace.span.INVALID_SPAN_CONTEXT:
            custom['trace_id'] = ctx.trace_id
            custom['span_id'] = ctx.span_id

    data["custom"] = custom
    return payload

rollbar.events.add_payload_handler(transform_rollbar_payload)

When I configure it like this, the RollbarNotifierMiddleware sees that there is an access token in the Rollbar settings and then unconditionally calls rollbar.init:

pyrollbar/rollbar/contrib/django/middleware.py

Line 202 in 205d904

rollbar.init(access_token, environment, **kw)

But when this happens, the rollbar.init() calls rollbar.events.reset(). This clears out my previously-added payload handler since it was added prior to Django initializing middleware and thus the RollbarNotifierMiddleware invoking rollbar.init().

I see a few options, none of which I'm particularly thrilled about:

1. Subclass RollbarNotifierMiddleware, call super.__init__(), and then call rollbar.events.add_payload_handler() (this is the one I went with):

   class TracedRollbarNotifierMiddleware(RollbarNotifierMiddleware):
       """
       The default RollbarNotifierMiddleware unconditionally does a rollbar.init() itself with the given access token
       """
       def __init__(self, get_response=None):
           super().__init__(get_response)
           import rollbar
           from django.conf import settings
   
           def transform_rollbar_payload(
                   payload: Dict[str, Any], **kwargs: Dict[str, Any]
           ) -> Dict[str, Any]:
               data = payload["data"]
               custom = data.get("custom", {})
   
               custom['service'] = settings.SERVICE
               custom['env'] = settings.ENVIRONMENT
               custom['version'] = settings.VERSION
               span = trace.get_current_span()
               if span != trace.span.INVALID_SPAN:
                   ctx = span.get_span_context()
                   if ctx != trace.span.INVALID_SPAN_CONTEXT:
                       custom['trace_id'] = ctx.trace_id
                       custom['span_id'] = ctx.span_id
   
               data["custom"] = custom
               return payload
   
           rollbar.events.add_payload_handler(transform_rollbar_payload)

2. Move the event handler registration to within a Django AppConfig.ready(), I presume this happens after middleware instantiation
3. Call rollbar.init() myself, but still set a ROLLBAR = {'access_token': 'not-used'} in settings.py so that the middleware will still be activated (RollbarNotifierMiddleware is skipped unless this is set)

So what is the intended use of event handlers with the RollbarNotifierMiddleware? Where in the lifecycle should I be adding these?