from urllib.parse import parse_qs

from .exposition import _bake_output

from .registry import REGISTRY

def make_asgi_app(registry=REGISTRY):

"""Create a ASGI app which serves the metrics from a registry."""

async def prometheus_app(scope, receive, send):

assert scope.get("type") == "http"

# Prepare parameters

params = parse_qs(scope.get('query_string', b''))

accept_header = "Accept: " + ",".join([

value.decode("utf8") for (name, value) in scope.get('headers')

if name.decode("utf8") == 'accept'

])

# Bake output

status, header, output = _bake_output(registry, accept_header, params)

# Return output

payload = await receive()

if payload.get("type") == "http.request":

await send(

{

"type": "http.response.start",

"status": int(status.split(' ')[0]),

"headers": [

tuple(x.encode('utf8') for x in header)

]

}

)

await send({"type": "http.response.body", "body": output})

return prometheus_app