Redirect all logs to file when MM_LOG is set.

[artemii235]

There're some deps now that use log crate for logging and this output is not forwarded to log file. We need to find a way to forward them too because they can contain very important information about what's going on in libp2p behaviours.

[sergeyboyko0791]

Changes were pushed into mm2.1 branch.
I think we can keep this issue opened until the features is tested

[artemii235]

Well done! I like a lot that we now have both log level and location of a print, e.g.

01 09:41:22, mm2src/gossipsub/src/behaviour.rs:543] INFO IAmrelay: Adding peer: PeerId("12D3KooWMUb8S5dgco2xypT87ey7fpdfidpjTxhhkRRF24Z7mvSb") to the relay mesh

I have a question ref this: is it possible to cut path segments from log, e.g print behaviour.rs instead of mm2src/gossipsub/src/behaviour.rs etc?

[sergeyboyko0791]

is it possible to cut path segments from log, e.g print behaviour.rs instead of mm2src/gossipsub/src/behaviour.rs etc?

Yes, we can do this using the std::path::Path or a regex.

[sergeyboyko0791]

@artemii235 I've tried to figure out how to cut the path like behaviour.rs instead of mm2src/gossipsub/src/behaviour.rs. Seems to be easiest to fork log4rs crate (i'd like to avoid this way) or rewrite the pretty useful log4rs pattern encoder. The second way deprives us of the ability to easily customize the log formats.
Is it actually needed to cut the path? We also should not cut crates paths, because we can get lost in lib.rs] entries :D

[artemii235]

Seems to be easiest to fork log4rs crate (I'd like to avoid this way)

Yeah, I'd like to avoid this too 🙂

Is it actually needed to cut the path?

It is ok to have the mm2src/gossipsub/src/behaviour.rs:543] path as it is quite short. But we get the full absolute path to a cargo dependency source, e.g. ~/.cargo/git/checkouts/rust-libp2p-7e56a40c55e2681f/6a5600f/protocols/ping/src/protocol.rs:108], which looks excessive.

I guess we can copy the pattern encoder and slightly customize it to cut the file path - maybe even submit a PR to log4rs then. Not a high priority so we can do this later.

[artemii235]

@sergeyboyko0791 Thanks for implementing this 🙂