aiohttp: variable routes are tagged with different paths

[lazitski-aliaksei]

If app uses variable route, requests with this urls are tagged with full path, which varies between requests.

For example:

...
app.add_route('/some/resource/{some_id}/child', handler)
...

Requests to this route are send to dogstatsd with full path, i.e.:

http_request_duration{method="GET",path="/some/resource/36d12223-1454-461c-9ed5-6d6777d98e80/child" ,",status="200",quantile="0.5"} 0.007255767000060587

It could be more convenient if such requests are reported with path pattern, i.e.:

http_request_duration{method="GET",path="/some/resource/{some_id}/child" ,",status="200",quantile="0.5"} 0.007255767000060587

Quick research shows that this info can be retrieved from request.match_info.route.resource.canonical, but this looks suspiciously long construction to be reliable. ;)