Add trace logging to fuel core

[freesig]

This adds a tracing subscriber to any of our tests but it is behind the env var FUEL_TRACE so it doesn't collide with any downstream or custom subscribers.:

Usage

To enable tracing for a test, add the following to the lib.rs file of the crate you want to trace:

#[cfg(test)]
fuel_core_trace::enable_tracing!();

If you also want tracing in your integration tests, you need to add the above to each integration tests file.

Tracing is still disabled by default so to enable it set the following environment variable:

export FUEL_TRACE=1

Or if you just want it for a single test run:

FUEL_TRACE=1 cargo test

Now you will have error level tracing like:

2023-01-25T02:27:14.362856Z ERROR works: tracing: I'm visible if FUEL_TRACE=1 is set

You can use the RUST_LOG environment variable to control the level of tracing you want to see. For example:

FUEL_TRACE=1 RUST_LOG=trace cargo test

Additional Subscribers

You can set a few different types of subscribers:

Compact output:

FUEL_TRACE=compact cargo test

Pretty output:

FUEL_TRACE=pretty cargo test

Log to file:

FUEL_TRACE=log-file cargo test

Log to file and output to console:

FUEL_TRACE=log-show cargo test

You can also set the log file path:

FUEL_TRACE_PATH=/some/path FUEL_TRACE=log-file cargo test

If you don't set the path, it will default to CARGO_MANIFEST_DIR/logs/logfile.