#cli #pretty-print #pretty #logs #bunyan

bin+lib bunyan

A CLI to pretty print structured logs. A Rust port of the original JavaScript bunyan CLI.

2 unstable releases

new 0.1.0 Oct 17, 2020
0.0.1 Oct 15, 2020


230 lines


A Rust port of node-bunyan.

Structured logs are the greatest thing since sliced bread.

Are you annoyed from having to install npm just to get a copy of the amazing NodeJS bunyan CLI to pretty-print your logs?

I feel you!

That's why I wrote bunyan-rs, a Rust port of (a subset of) the original NodeJS bunyan CLI.

Table of Contents

  1. How to install
  2. How to use
  3. Limitations
  4. Bunyan ecosystem in Rust
  5. Benchmarks
  6. License

How to install

Using cargo:

cargo install bunyan

You can verify your installation with

bunyan --help

How to use

bunyan-rs only supports stdin as input source.

You can pipe a log file into it:

cat tests/all/corpus/all.log | bunyan

Or you can pipe the output of a long-running job into it:

# Tail logs from a Docker container
docker logs -f my-app | bunyan

# Tail logs from a Kubernetes pod using kubectl
kubectl logs -f my-app-asdadf-cvcvcv

# Tail logs from a group of Kubernetes pods using stern
stern "my-app" --output raw --tail 100 | bunyan


Compared to the original bunyan CLI, bunyan-rs:

  • Only supports stdin as input source (no files);
  • Does not support log snooping via DTrace (-p argument);
  • Does not support the -c/--condition filtering mechanism;
  • Does not support the --pager/--no-pager flags;
  • Only supports the long output format;
  • Only supports UTC format for time.

Some of the above might or might not be added in the future.
If you are interested in contributing, please open an issue.

Bunyan ecosystem in Rust

You are writing a Rust application and you'd like to emit logs in bunyan format - what can you use?

Check out the following crates:


Speed has never been a burning problem while eyeballing logs from applications, but any speed-up to the tools I use on a daily basis is always appreciated.

To benchmark bunyan-rs against the original NodeJS bunyan follow these steps:

  • Build bunyan-rs using the release profile:
cargo build --release
  • Install bunyan via npm. You will need npx as well;
  • Benchmark!
# bunyan JS
time ./benchmark_js.sh benchmark_logs.txt
# bunyan-rs
time ./benchmark_rs.sh benchmark_logs.txt

On my system bunyan-rs is roughly 5x faster on this very non-scientific and highly inaccurate benchmark - your mileage may vary.
The Rust code is highly non-optimised (we are allocating freely and wastefully!) - streamlining it could be a fun exercise.


Licensed under either of Apache License, Version 2.0 or MIT license at your option. Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this crate by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.


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