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Our logging library `tracing` supports structured logging. Structured logging means we can include values within a `tracing::Event` without having to immediately format it as a string. Processing these values - such as errors - as their original type allows the various `tracing` layers to capture and represent them as they see fit. One of these layers is responsible for sending ERROR and WARN events to Sentry, as part of which `std::error::Error` values get automatically captured as so-called "sentry exceptions". Unfortunately, there is a caveat: If an `std::error::Error` value is included in an event that does not get mapped to an exception, the `error` field is completely lost. See https://github.com/getsentry/sentry-rust/issues/702 for details. To work around this, we introduce a `err_with_sources` adapter that an error and all its sources together into a string. For all `tracing::debug!` statements, we then use this to report these errors. It is really unfortunate that we have to do this and cannot use the same mechanism, regardless of the log level. However, until this is fixed upstream, this will do and gives us better information in the log submitted to Sentry.
Rust development guide
Firezone uses Rust for all data plane components. This directory contains the Linux and Windows clients, and low-level networking implementations related to STUN/TURN.
We target the last stable release of Rust using rust-toolchain.toml.
If you are using rustup, that is automatically handled for you.
Otherwise, ensure you have the latest stable version of Rust installed.
Reading Client logs
The Client logs are written as JSONL for machine-readability.
To make them more human-friendly, pipe them through jq like this:
cd path/to/logs # e.g. `$HOME/.cache/dev.firezone.client/data/logs` on Linux
cat *.log | jq -r '"\(.time) \(.severity) \(.message)"'
Resulting in, e.g.
2024-04-01T18:25:47.237661392Z INFO started log
2024-04-01T18:25:47.238193266Z INFO GIT_VERSION = 1.0.0-pre.11-35-gcc0d43531
2024-04-01T18:25:48.295243016Z INFO No token / actor_name on disk, starting in signed-out state
2024-04-01T18:25:48.295360641Z INFO null
Benchmarking on Linux
The recommended way for benchmarking any of the Rust components is Linux' perf utility.
For example, to attach to a running application, do:
- Ensure the binary you are profiling is compiled with the
benchprofile. sudo perf perf record -g --freq 10000 --pid $(pgrep <your-binary>).- Run the speed test or whatever load-inducing task you want to measure.
sudo perf script > profile.perf- Open profiler.firefox.com and load
profile.perf
Instead of attaching to a process with --pid, you can also specify the path to executable directly.
That is useful if you want to capture perf data for a test or a micro-benchmark.