Daphne health-check

[edevil]

It would be nice for Daphne to support an endpoint that would allow an health check on itself and the channel layer subsystem, with no need for active workers. Maybe send a message on a predefined channel and check if it receives it?

Right now, when we launch the Daphne component, there's no URL that I know of that we can query to check if just the Daphne component is healthy. We need active workers to respond to request, and so it's harder to diagnose a problem.

[robmoorman]

The healthcheck would also be prefeffered in case you use Amazon ECS. A http health check is required to check whether daphne is healthy or not.

[andrewgodwin]

As of Daphne 2.0 the application is in-process so you can get a health check with a simple Django view.