Count active subscriptions

[AlexanderWells-diamond]

I'm trying to get a count of the number of active subscriptions in my Strawberry server. I have been unable to find how to do this. For reference I'm using an aiohttp server.

I've tried a variety of methods:

• Using custom extensions. These do not seem to trigger for subscriptions at all.
• Examining the various Tracing extensions. None of these appear to offer subscription tracking.
• Looking through Strawberry code. I found the BaseGraphQLTransportWSHandler class, which seems to have a dictionary of subscriptions. However, it doesn't seem to be possible to access this - the GraphQLView that we pass to aiohttp dynamically creates new instances for every request , meaning that there's no way to access this data from the GraphQLView (or anywhere for that matter as the reference is lost)
• Looking at aiohttp itself, but it does not seem to support any websocket connection tracing.

Is there something I've missed? Thanks for any help!

[DoctorJohn]

Hey @AlexanderWells-diamond, currently I can't think of an trivial way to achieve this. The aiohttp view creates a new instance of strawberry.aiohttp.handles.GraphQLTransportWSHandler for each incoming ws connection using the graphql-transport-ws protocol. You could subclass said class and extend its handle_request method to keep track of individual connections by updating some global counter.

The code could look roughtly like this:

from strawberry.aiohttp.handlers import GraphQLTransportWSHandler
from strawberry.aiohttp.views import GraphQLView
from aiohttp import web

some_global_counter = 0


class CustomHandler(GraphQLTransportWSHandler):
  async def handle_request(self):
    some_global_counter = some_global_counter + 1
    await super().handle_request()
    some_global_counter = some_global_counter - 1


class CustomView(GraphQLView):
  graphql_transport_ws_handler_class = CustomHandler


schema = ... # your schema

app = web.Application()
app.router.add_route("*", "/graphql", GraphQLView(schema=schema))

Note that I haven't tested it, just wanted to give you a starting point to a potential solution.

[AlexanderWells-diamond]

Thank you for the suggestion! I'll give it a try

[AlexanderWells-diamond]

Thank you for this, it seems to do exactly what I wanted.

For anyone else who stumbles across this: I was trying to set up metrics tracking with aioprometheus, specifically using its @inprogress decorator. This code seems to work as you'd expect to track subscriptions:

class MetricsGraphQLTransportWSHandler(GraphQLTransportWSHandler):
    @inprogress(
        REQUESTS_IN_PROGRESS, labels={"type": "subscription_GraphQLTransportWS"}
    )
    async def handle_request(self):
        await super().handle_request()