Cosmian Logger

A flexible logging crate that supports both synchronous and asynchronous environments.

Features

• full: Enables complete functionality including OpenTelemetry integration, syslog support, and advanced tracing features
• Without full: Provides basic tracing functionality for synchronous applications

⚠️ Important: If you need TelemetryConfig or OpenTelemetry functionality, you must enable the full feature:

[dependencies]
cosmian_logger = { version = "0.5.2", features = ["full"] }

Usage

With Full Features

For applications that need OpenTelemetry and advanced features:

[dependencies]
cosmian_logger = { version = "0.5.2", features = ["full"] }

use cosmian_logger::{tracing_init, TelemetryConfig, TracingConfig};

#[tokio::main]
async fn main() {
    let config = TracingConfig {
        service_name: "my-service".to_string(),
        otlp: Some(TelemetryConfig {
            version: Some("1.0.0".to_string()),
            environment: Some("production".to_string()),
            otlp_url: "http://localhost:4317".to_string(),
            enable_metering: true,
        }),
        no_log_to_stdout: false,
        with_ansi_colors: true,
        ..Default::default()
    };

    let _guard = tracing_init(&config);

    tracing::info!("Application started");
}

Without Full Features (Basic Mode)

For synchronous applications that only need basic logging:

[dependencies]
cosmian_logger = "0.5.2"

use cosmian_logger::{tracing_init, TracingConfig};

fn main() {
    let config = TracingConfig {
        service_name: "my-sync-service".to_string(),
        no_log_to_stdout: false,
        with_ansi_colors: true,
        // Note: otlp field is not available without full feature
        ..Default::default()
    };

    let _guard = tracing_init(&config);

    tracing::info!("Synchronous application started");
}

Logging Macros

The crate provides logging macros that work with or without the full feature:

use cosmian_logger::{info, debug, warn, error, trace};

// Function name is automatically prefixed to log messages
info!("Application initialized");
debug!(user_id = 123, "Processing user request");
warn!("Low memory warning");
error!(error = %err, "Operation failed");

Features Summary

• Basic logging: stdout, file, and structured logging support
• OpenTelemetry (requires full feature): OTLP tracing and metrics
• Syslog support (requires full feature): System log integration
• Structured logging: Multiple message patterns supported
• ANSI colors: Configurable for interactive vs persistent outputs

A versatile logging and tracing utility for Rust applications that provides:

• Structured logging to stdout
• Syslog integration
• OpenTelemetry support for distributed tracing
• Runtime configuration options

Installation

Add the dependency to your Cargo.toml:

[dependencies]
cosmian_logger = { path = "../path/to/crate/logger" }

Basic Usage

For simple applications, use the log_init function to set up logging:

use cosmian_logger::log_init;
use tracing::{debug, info};

fn main() {
    // Initialize with custom log level
    log_init(Some("debug"));

    info!("This is an info message");
    debug!("This is a debug message");
}

The log_init function accepts an optional log level string parameter:

• When None is provided, it falls back to the RUST_LOG environment variable
• Log levels follow Rust's standard: trace, debug, info, warn, error

Advanced Configuration with OpenTelemetry

For more advanced use cases with OpenTelemetry integration, enable the full feature:

[dependencies]
cosmian_logger = { version = "0.5.2", features = ["full"] }

use cosmian_logger::{tracing_init, TelemetryConfig, TracingConfig};
use tracing::span;
use tracing_core::Level;

#[tokio::main]
async fn main() {
    let config = TracingConfig {
        service_name: "my_service".to_string(),
        otlp: Some(TelemetryConfig {
            version: Some("1.0.0".to_string()),
            environment: Some("development".to_string()),
            otlp_url: "http://localhost:4317".to_string(),
            enable_metering: true,
        }),
        no_log_to_stdout: false,
        #[cfg(not(target_os = "windows"))]
        log_to_syslog: true,
        rust_log: Some("debug".to_string()),
        ..Default::default()
    };

    let _otel_guard = tracing_init(&config);

    // Create and enter a span for better tracing context
    let span = span!(Level::TRACE, "application");
    let _span_guard = span.enter();

    // Your application code here
    tracing::info!("Application started");
}

OpenTelemetry Setup

To use OpenTelemetry, start a collector like Jaeger:

docker run -p16686:16686 -p4317:4317 -p4318:4318 \
-e COLLECTOR_OTLP_ENABLED=true -e LOG_LEVEL=debug \
jaegertracing/jaeger:2.5.0

Then access the Jaeger UI at http://localhost:16686

Configuration Options

The TracingConfig struct supports:

• service_name: Name of your service for tracing
• otlp: OpenTelemetry configuration (only available with full feature)
• no_log_to_stdout: Disable logging to stdout
• log_to_syslog: Enable logging to system log (only available with full feature)
• rust_log: Log level configuration
• with_ansi_colors: Enable ANSI colors in output
• log_to_file: Optional file logging configuration

In Tests

The log_init function is safe to use in tests:

#[test]
fn test_something() {
    cosmian_logger::log_init(Some("debug"));
    // Your test code
}

Re-exports

The logger crate re-exports common tracing utilities:

use cosmian_logger::reexport::{tracing, tracing_subscriber};