clojog

A simple wrapper for customized SLF4J/Logback usage with colored output

This is a Java port of the original Go zylog library, providing the same clean, colored logging interface for Java applications.

Features

• Simple Setup: One-line configuration to get beautiful, structured logs
• Colored Output: Configurable ANSI color support with cross-platform compatibility
• Flexible Levels: Support for all standard log levels (TRACE, DEBUG, INFO, WARN, ERROR)
• Multiple Outputs: Log to stdout, stderr, or (planned) filesystem
• Caller Information: Optional method/line number reporting
• Structured Logging: Full MDC (Mapped Diagnostic Context) support
• Maven Central Ready: Configured for easy publishing and distribution

Installation

Maven Dependency

Add to your project's pom.xml:

<dependencies>
    <dependency>
        <groupId>io.github.clojang</groupId>
        <artifactId>clojog</artifactId>
        <version>0.1.8</version>
    </dependency>
</dependencies>

Gradle Dependency

Add to your build.gradle:

dependencies {
    implementation 'io.github.clojang:clojog:0.1.8'
}

SBT Dependency (Scala)

Add to your build.sbt:

libraryDependencies += "io.github.clojang" % "clojog" % "0.1.0"

Leiningen Dependency (Clojure)

Add to your project.clj:

:dependencies [[io.github.clojang/clojog "0.1.0"]]

Quick Start

Here's a simple example to get you started:

import io.github.clojang.clojog.Clojog;
import io.github.clojang.clojog.ClojogOptions;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class MyApp {
    private static final Logger log = LoggerFactory.getLogger(MyApp.class);
    
    public static void main(String[] args) {
        // Setup logging with colors
        Clojog.setupLogging(new ClojogOptions()
            .setColored(true)
            .setLevel("INFO")
            .setOutput("stdout")
            .setReportCaller(false));
        
        log.info("You are standing in an open field west of a white house.");
        log.warn("It is pitch black. You are likely to be eaten by a grue.");
    }
}

Configuration

Configure clojog using the ClojogOptions class:

ClojogOptions options = new ClojogOptions()
    .setColored(true)           // Enable ANSI colors
    .setLevel("DEBUG")          // Set minimum log level
    .setOutput("stdout")        // Output destination
    .setReportCaller(true);     // Include caller info

Clojog.setupLogging(options);

Configuration Options

Option	Type	Default	Description
colored	boolean	true	Enable/disable ANSI color output
level	String	"INFO"	Minimum log level (TRACE, DEBUG, INFO, WARN, ERROR)
output	String	"stdout"	Output destination (stdout, stderr)
reportCaller	boolean	false	Include class, method, and line number in logs

Output Format

clojog produces clean, structured log output:

Without caller info:

2024-01-15T10:30:45-05:00 INFO ▶ Application started successfully

With caller info:

2024-01-15T10:30:45-05:00 INFO [com.example.MyApp.main:23] ▶ Application started successfully

With structured data (MDC):

MDC.put("userId", "12345");
MDC.put("requestId", "req-abc");
log.info("User logged in");

2024-01-15T10:30:45-05:00 INFO ▶ User logged in || userId={12345}, requestId={req-abc}

Structured Logging

clojog fully supports SLF4J's MDC (Mapped Diagnostic Context) for structured logging:

import org.slf4j.MDC;

// Add context
MDC.put("userId", "12345");
MDC.put("sessionId", "session-abc");

log.info("Processing user request");

// Clear context when done
MDC.clear();

Color Scheme

Different log levels are colored for easy visual scanning:

• TRACE: Magenta
• DEBUG: Cyan
• INFO: Green
• WARN: Yellow
• ERROR: Red

Colors automatically disable on non-TTY outputs and can be manually disabled.

Demo Application

Run the demo to see clojog in action:

mvn compile exec:java -Dexec.mainClass="io.github.clojang.clojog.demo.DemoApp"

Integration with Configuration Libraries

clojog works great with configuration libraries like Spring Boot's configuration or other property systems:

// Spring Boot example
@Value("${logging.colored:true}")
private boolean colored;

@Value("${logging.level:INFO}")
private String level;

@PostConstruct
public void setupLogging() {
    Clojog.setupLogging(new ClojogOptions()
        .setColored(colored)
        .setLevel(level)
        .setOutput("stdout")
        .setReportCaller(false));
}

Building from Source

git clone https://github.com/clojang/clojog.git
cd clojog
mvn clean install

Publishing to Maven Central

This project is configured for publishing to Maven Central. See the publishing guide in docs/PUBLISHING.md for details.

Background

This library is inspired by and ports the Go zylog library, which in turn was inspired by:

• Twig (Clojure)
• Logjam (LFE)

The goal is to provide clean, readable, structured logging across different platforms and languages.

License

© 2025, Clojang. All rights reserved.

Licensed under the Apache License, Version 2.0. See LICENSE file for details.