Crate structured_logger

Structured Logger

A logging implementation for the log crate that logs structured values either synchronous or asynchronous, in JSON, CBOR, or any other format, to a file, stderr, stdout, or any other destination. To initialize the logger use the Builder struct. It is inspired by std-logger.

This crate provides only a logging implementation. To do actual logging use the log crate and it’s various macros.

Limiting logging targets

You can use Builder::with_target_writer method to log messages related specific target to a specific writer.

Crate features

This crate has three features:

• log-panic, enabled by default.

Log-panic feature

The log-panic feature will log all panics using the error severity, rather then using the default panic handler. It will log the panic message as well as the location and a backtrace, see the log output for an panic_log example.

Examples

• Log panics example: https://github.com/iorust/structured-logger/blob/main/examples/panic_log.rs
• Async log example: https://github.com/iorust/structured-logger/blob/main/examples/async_log.rs

Muilti writers example:

use serde::Serialize;
use std::{fs::File, io::stdout};
use structured_logger::{json::new_writer, unix_ms, Builder};

fn main() {
    // Initialize the logger.
    // Optional: create a file to write logs to.
    let log_file = File::options()
        .create(true)
        .append(true)
        .open("app.log")
        .unwrap();

    // or Builder::with_level("debug")
    Builder::new()
        // Optional: set a specific writer (format to JSON, write to stdout) for target starts with "api".
        .with_target_writer("api*", new_writer(stdout()))
        // Optional: set a specific writer (format to JSON, write to app.log file) for target "file" and "db".
        .with_target_writer("file,db", new_writer(log_file))
        .init();

    let kv = ContextLog {
        uid: "user123".to_string(),
        action: "upate_book".to_string(),
    };

    log::info!("hello world");
    // This log will be written to stderr (default writer):
    // {"level":"INFO","message":"hello world","target":"simple","timestamp":1679745592127}

    log::info!(target: "api",
        method = "GET",
        path = "/hello",
        status = 200_u16,
        start = unix_ms(),
        elapsed = 10_u64,
        kv = log::as_serde!(kv);
        "",
    );
    // This log will be written to stdout:
    // {"elapsed":10,"kv":{"uid":"user123","action":"upate_book"},"level":"INFO","message":"","method":"GET","path":"/hello","start":1679745592127,"status":200,"target":"api","timestamp":1679745592127}

    log::info!(target: "file",
        method = "GET",
        path = "/hello",
        status = 200_u16,
        start = unix_ms(),
        elapsed = 10_u64,
        kv = log::as_serde!(kv);
        "",
    );
    // This log will be written to file "app.log":
    // {"elapsed":10,"kv":{"uid":"user123","action":"upate_book"},"level":"INFO","message":"","method":"GET","path":"/hello","start":1679745592127,"status":200,"target":"file","timestamp":1679745592127}
}

#[derive(Serialize)]
struct ContextLog {
    uid: String,
    action: String,
}

Modules

• async_json
  Async JSON Writer Implementation
• json
  Sync JSON Writer Implementation

Structs

• Builder
  A struct to initialize the logger for log crate.

Traits

• Writer
  A trait that defines how to write a log. You can implement this trait for your custom formatting and writing destination.

Functions

• get_env_level
  Returns the log level from the environment variables: LOG, LOG_LEVEL, RUST_LOG, TRACE or DEBUG. Default is INFO.
• log_failure
  A fallback logging function that is used in case of logging failure in Writer implementation. It will write failure information in JSON to stderr.
• unix_ms
  Returns the current unix timestamp in milliseconds.