# rust-cli/env_logger

A logging implementation for `log` which is configured via an environment variable.

Repository: https://github.com/rust-cli/env_logger
Canonical: https://ross.abutalabs.com/products/env_logger
Homepage: https://docs.rs/env_logger
Language: Rust
License: Apache-2.0
License Family: permissive
Last push: 2026-08-20T21:09:10+00:00

## Health v2 (maintenance only)
Score: 91/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 98, release rhythm 78, longevity 100
- inputs: {"age_days": 3345, "days_push": 13, "days_rel": 69, "gap_med": 80, "n_releases_24m": 6}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1063, forks 147 (observed 2026-08-28T04:03:26.378701+00:00)

## What it is
env_logger is a Rust logging implementation for the `log` crate facade that can be configured via the RUST_LOG environment variable. It is intended for use in executables and tests, providing level filtering, colored output, and flexible builder-based configuration.

## Use cases
- add logging to a Rust CLI binary
- control log verbosity with RUST_LOG environment variable
- filter log messages per module with log levels
- see log output when running Rust tests
- configure a logger without a config file

## When to choose
- you are building a Rust executable or CLI and need simple, zero-config logging
- you want users to control log levels via an environment variable
- you want a lightweight default logger for the log crate facade
- you need logging in Rust integration or unit tests

## When to avoid
- you are writing a library - use the log crate facade instead
- you need structured logging, log shipping, or backends like syslog or OpenTelemetry
- you need async or high-performance logging like tracing or slog
- you need runtime-reconfigurable logging from a file or remote service

## Facets
- artifact type: library
- maturity: stable
- function: logging
- domain: developer-tools, backend
- platform: rust, cross-platform, cli
- tags: log-crate, rust-log, environment-variable-config, stderr-logging, command-line

## Member repositories
- rust-cli/env_logger (main) score 91

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:03:26.378701+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T06:56:40.797052+00:00, confidence not recorded.
  - readme: https://github.com/rust-cli/env_logger (fetched 2026-08-28T04:03:26.378701+00:00, sha 3bfd59ab09fa)
  - homepage: https://docs.rs/env_logger (fetched 2026-08-29T12:58:25.758078+00:00, sha f33adf831ad4)
  - site_page: https://docs.rs/ (fetched 2026-08-29T12:58:25.761168+00:00, sha 607ae64b9953)
  - site_page: https://docs.rs/crate/env_logger/latest (fetched 2026-08-29T12:58:25.763119+00:00, sha 99d266659430)
  - site_page: https://docs.rs/crate/env_logger/latest/features (fetched 2026-08-29T12:58:25.765188+00:00, sha 4b0951b38ba5)
  - site_page: https://docs.rs/about (fetched 2026-08-29T12:58:25.766827+00:00, sha 29ab7986fbf5)
  - site_page: https://docs.rs/about/badges (fetched 2026-08-29T12:58:25.768435+00:00, sha 6588cac258af)
  - site_page: https://docs.rs/about/builds (fetched 2026-08-29T12:58:25.769907+00:00, sha 811231ca4680)
  - site_page: https://docs.rs/about/metadata (fetched 2026-08-29T12:58:25.771537+00:00, sha 0dcdccb2b2b2)
  - site_page: https://docs.rs/about/redirections (fetched 2026-08-29T12:58:25.773496+00:00, sha 1b1efd93105f)
- Data as of 2026-08-30T08:39:29.467469+00:00.