Set up logging

[dgreisen]

We've seen how difficult it is to use our current ad hoc logs. So I think this is something that is worth doing right.

actix uses logger: https://actix.rs/docs/middleware/#logging
blessed recommends tracing: https://blessed.rs/crates#section-common-subsection-logging
actix middleware for tracing: https://docs.rs/tracing-actix-web/latest/tracing_actix_web/
explanation of theory behind tracing: https://www.lpalmieri.com/posts/2020-09-27-zero-to-production-4-are-we-observable-yet/

@tombh - do you have any experience with logging?

[tombh]

Yes, in my last Rust contract we used tracing in a web server. It's pretty straight forward to get started. The difficult bit was getting performance tracing "spans" inside the middleware. Such performance logging can be useful for event reporting, for example: notify admin when a request takes longer than 5 seconds.

I could make a "getting started" PR for tracing?

[dgreisen]

@tombh that would be excellent, thank you!