47e45a3cf3
DNS resolution is a critical part of `connlib`. If it is slow for whatever reason, users will notice this. To make sure we notice as well, we add `telemetry` spans to the client's and gateway's DNS resolution. For the client, this applies to all DNS queries that we forward to the upstream servers. For the gateway, this applies to all DNS resources. In addition to those IO operations, we also instrument the `match_resource_linear` function. This function operates in `O(n)` of all defined DNS resources. It _should_ be fast enough to not create an impact but it can't hurt to measure this regardless. Lastly, we also instrument `refresh_translations` on the gateway. Refreshing the DNS resolution of a DNS resource should really only happen, when the previous IP addresses become stale yet the user is still trying to send traffic to them. We don't actually have any data on how often that happens. By instrumenting it, we can gather some of this data. To make sure that none of these telemetry events and spans hurt the end-user performance, we introduce macros to `firezone-logging` that sample the creation of these events and spans at a rate of 1%. I ran a flamegraph and none of these even showed up. The most critical one here is probably the `match_resource_linear` span because it happens on every DNS query. Resolves: #7198. --------- Signed-off-by: Thomas Eizinger <thomas@eizinger.io>
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.