Exposing GET handler for health check

[tarrencev]

Is there a recommended approach to exposing a GET handler for i.e. health checks or metrics on the base server? It doesn't seem possible to register additional handlers today. I has hoping build_from_hyper would help with this but it still doesn't give access to the underlying service builder.

Related eqlabs/pathfinder#194

[niklasad1]

You referring to the HTTP server correct?

So currently, we have the middleware that you can use to collect metrics based on the timings but not a health API or any mean to register additional handlers.

However, I have nothing against to expose a health API on the HTTP server sounds like a good idea.

If you want to implement it that would be great.

[tarrencev]

Yes thats correct. Awesome. It seems like a health check would be quite specific to the consumer service, since it might depend on the service implementation. Do you have an idea of what an interface might look like?

[niklasad1]

I think the jsonrpc crate health API looks quite clean.

I'm not exactly sure if how likely it's that folks would want to provide their own HTTP status codes, jsonrpc for instance let you define a RPC call and if that fails it will be converted to status code 500. That's quite simple to use at least.

Would be neat to have something a bit more flexible such as (a closure could work too):

trait HealthApi {
    fn health(&self) -> (StatusCode, Body);
}

server impl

 builder.health_api(set_handler());

 match (request.method(), server.get_health_api()) {
    (handler, Method::GET)  {
       let (status_code, body) = handler.health();
       send_http_response(status_code, body);
    }
 }  

[niklasad1]

sorry @tarrencev I realized that we need this ASAP too.

So I have opened #763 I hope that will fix things for you, sorry for not letting you implement that.

we could revisit the API at a later point, if someone comes up with something more better.

[niklasad1]

Closed by #763

[tarrencev]

Awesome appreciate you taking care of this!