Product sample · Rust
Findr
A log analysis CLI written in Rust with no external crates. It parses JSON lines and key=value logs, filters with expressions, aggregates counts and percentiles, finds top values and follows a file in tail mode.
Rustlanguage
0crates
59tests
stats, top, filter, tailcommands
The problem
Logs are easy to read once.
Reading one log line is trivial. Answering questions across a million of them at 2am is not: what is the p99 latency, which endpoint is slowest, what changed after the deploy?
Findr answers those questions from the shell, with a parser that is strict about malformed lines and commands that print either a table for humans or JSON for another tool.
What we built
One binary, no dependencies.
- Parser for JSON lines and key=value formats, with dotted keys flattened into one namespace.
- Filter expressions: equality, inequality, contains and numeric comparisons, combined with AND.
- Aggregations: count, min, max, sum, mean, p50, p95 and p99 per field.
- Top-N by any field, and a tail mode that polls a file and follows truncation.
- CLI output as a table, JSON or raw values, with a strict mode for malformed input.
Architecture
How it is put together
src/ ├─ parser.rs (json + kv, typed values) ├─ filter.rs (expression parsing and evaluation) ├─ stats.rs (count, sum, percentiles) ├─ aggregate.rs (grouping, top-N) ├─ tail.rs (follow, truncation) └─ main.rs (CLI) tests/cli.rs integration tests spawn the binary against fixtures scripts/test.sh runs cargo test
Stack
Rust 2024std only
Security and money
- Zero dependencies means the binary is small and `cargo test` runs offline in CI.
- Percentiles use the nearest-rank method and the README states it, so the numbers can be checked.
- Malformed lines are reported, not silently dropped; strict mode makes them fatal.
- The browser demo is a mirror of the parser and aggregation logic, and says so on the page.
Screens
Product surfaces
Similar work
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