feat(backend): allow to set log level via config file

[MichaIng]

If the "RUST_LOG" environment variable is set, it overrides the value from the config file, which makes testing and debugging easier without the need to adjust the config file and hence without affecting the default service.

Also the conversion from String to toml::Value to str back to String, then in main.rs from String back to str to log::Level somehow looks like an unnecessary loop. Fascinating that searching around for an hour or so I couldn't find a single example of how a String or str is converted into a log::Level or alternatively log::LevelFilter directly. Probably we can also store the environment valuable || config value || default also directly as log::Level?

[MichaIng]

@ravenclaw900
Okay I'm at the end of my trail&error attempts 😅. The issue is the different types of what these return:

• std::env::var() => String
• cfg.get() => &toml:Value
• and the fallback/default.

Not sure how to convert them best. Converting the env var + default both into &toml:Value, which just needs to be converted back to string, seems somehow unreasonable. Generally &toml:Value implements to_string(), but currently it fails "due to unsatisfied trait bounds". I guess this would need to be done in let cfg above, but not sure how to do correctly and whether this is really wanted.

Best would be actually to pass it as str, so no further conversion is required in main.rs.

Otherwise we could simply ignore the environment variable for now, but actually I like the option to use it for quick debugging 😉.

[ravenclaw900]

The problem was that you were trying to run to_string on an Option<&toml::Value>, not the &toml::Value itself. However, you're slightly overthinking it. No need for us to parse the environment variable, just let simple_logger do that for us. See the change I just pushed.

[MichaIng]

Ah, so a simply unwrap() was missing 😅. And dammit yes, with_level() prefers RUST_LOG anyway, when present. I forgot about this as I wanted to use init_with_level() first, which doesn't do that. But that one does not take a LevelFilter but a Level instead, which cannot be off, making it more complicated to allow disabling logging completely, hence I switched back to with_level().

I'll test this tomorrow.

[ravenclaw900]

Also, once I figure some things out with serde, I'll probably switch to an actual configuration library like figment, rendering most of this boilerplate redundant and allowing us to set all config file settings with environment variables.

[MichaIng]

There should be exclusions for login password and secret for security reasons, but otherwise sounds good.