https://github.com/stepancheg/rust-log-ndc

log crate extension with NDC-like functionality
https://github.com/stepancheg/rust-log-ndc

logging rust

Last synced: 3 months ago
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log crate extension with NDC-like functionality

• Host: GitHub
• URL: https://github.com/stepancheg/rust-log-ndc
• Owner: stepancheg
• License: mit
• Created: 2019-02-03T22:24:27.000Z (almost 6 years ago)
• Default Branch: master
• Last Pushed: 2021-02-22T22:10:49.000Z (almost 4 years ago)
• Last Synced: 2024-09-20T09:12:03.148Z (4 months ago)
• Topics: logging, rust
• Language: Rust
• Size: 22.5 KB
• Stars: 5
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE.txt

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README

        
# log crate extension with NDC-like functionality

[![Build Status](https://img.shields.io/travis/stepancheg/rust-log-ndc.svg)](https://travis-ci.org/stepancheg/log-ndc)

[![License](https://img.shields.io/crates/l/log-ndc.svg)](https://github.com/stepancheg/rust-log-ndc/blob/master/LICENSE.txt)

[![crates.io](https://img.shields.io/crates/v/log-ndc.svg)](https://crates.io/crates/log-ndc)

* `log-ndc` crate provides a logger which wraps arbitrary logger

  which prepends thread-local information to each log message

* `log-ndc-env-logger` is a very simple (10 lines of code) drop-in wrapper/replacement of `env_logger` crate

## log-ndc

This crate allows settings a thread-local variable which will be prepended to log messages.

`log_ndc::set_boxed_logger(logger)` wraps passed `logger` object with `log_ndc::Logger` and calls

underlying `log::set_boxed_logger(..)`.

`log_ndc` functions like `log_ndc::set(..)` or `log_ndc::push(..)` replace thread-local text

which is later prepended to log messages in the wrapper logger.

```

// works exactly like regular `warn!` macro with any logger

// `warn!` is a macro from `log` library

warn!("something happened");

// set thread-local information like request id

log_ndc::set(format!("reqid={}", 10));

info!("starting request");

// outputs

// INFO 2019-02-03T23:51:26Z: mycrate: [reqid=10] starting request

```

## log-ndc-env-logger

Drop-in replacement/wrapper of `env_logger` crate.

It simply initialzes `env_logger` wrapper and wraps it with `log_ndc::Logger`.

The crate is dead simple, have a look at

[single file source](https://github.com/stepancheg/rust-log-ndc/blob/master/log-ndc-env-logger/src/lib.rs).

## FAQ

(I think these are FAQ, however nobody asked me anything yet.)

### What what NDC means?

The word "NDC" is [taken from log4j](https://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/NDC.html),

it means "nested dianostics context".

### Is it compatible with `log` crate or my favorite backend?

Yes, `log-ndc` wraps logging backend and delegates it to `log` crate.

So all macros like `warn!(..)` should work as before.

## See also `log-mdc`

* [log-mdc](https://github.com/sfackler/rust-log-mdc) is a similar project, which allows storing thread-local

data by key. However, log-mdc is compatible only with certain loggers like

[log4rs](https://github.com/sfackler/log4rs). It is not possible to obtain thread-local information set in

`log-mdc` in when e. g. `env-logger` is used.

## Where should we go?

I think it would be right thing if `log` crate supported basic

thread-local context like provided in this crate.