I’m trying to add metrics to my Sanic app.
Prometheus provides Python client running as ASGI app – https://prometheus.github.io/client_python/exporting/http/asgi/ .

The question is how to run 2 ASGI apps at once.

I found Starlette could help:

from prometheus_client import make_asgi_app
from starlette.applications import Starlette
from starlette.routing import Mount
from sanic import Sanic
from sanic.response import text

sanic_app = Sanic("MyHelloWorldApp")

@sanic_app.get("/")
async def hello_world(request):
    return text("Hello, world.")

metrics_app = make_asgi_app()

routes = [
    Mount("/", app=sanic_app),
    Mount("/metrics", app=metrics_app)
]

app = Starlette(routes=routes)

if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="127.0.0.1", port=8000, log_level="info")

metrics_app mounted and works,
but Sunic returns an exception:

sanic.exceptions.SanicException: Loop can only be retrieved after the app has started running. Not supported with `create_server` function

Does anybody know a more straightforward way to use Prometheus Client with ASGI Sanic?