Applogger - The Structured Logging Library for Go

🚀 Overview

applogger is a structured logging library for Go that writes logs in NDJSON format (Newline Delimited JSON).

• Structured Logging: Outputs logs in JSON format for easy parsing.
• Log Levels: Supports Debug, Info, Warn, Error, and Fatal.
• Concurrency Safe: Uses mutex locking for safe concurrent writes.
• Automatic Caller Info: Captures the package and function where the log originated.
• HTTP Logging: Supports logging HTTP response codes and request durations.
• Context-Aware Logging: Supports extracting key-value pairs from context.Context.
• Graceful Shutdown: Ensures log files are properly closed on termination.

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📦 Installation

To install applogger, simply run:

go get -u github.com/junkd0g/applogger

🚀 Usage

Basic Logging

package main

import (
	"context"
	"log"
	"time"

	"github.com/junkd0g/applogger"
)

func main() {
	logger, err := applogger.NewLogger("app.log")
	if err != nil {
		log.Fatalf("Failed to initialize logger: %v", err)
	}
	defer logger.Close()

	// Add extra default fields.
	logger = logger.WithFields(map[string]interface{}{
		"service": "payment",
		"version": "1.0.3",
	})

	// Create a context with values.
	ctx := context.Background()
	ctx = context.WithValue(ctx, "user_id", "12345")
	ctx = context.WithValue(ctx, "request_id", "req-001")
	ctx = context.WithValue(ctx, "session_id", "sess-789")

	// Log a simple message.
	logger.Log(ctx, applogger.Info, "Service started successfully")

	// Log an HTTP-related event.
	logger.LogHTTP(ctx, applogger.Debug, "HTTP response received", 200, 0.456)

	// Wait a moment to see different timestamps.
	time.Sleep(1 * time.Second)

	// Log an error.
	logger.Log(ctx, applogger.Error, "Encountered an unexpected error")
}

Logging with Context (Key-Value Pair Extraction)

package main

import (
	"context"
	"github.com/junkd0g/applogger"
)

func main() {
	logger, _ := applogger.NewLogger("app.log")
	defer logger.Close()

	ctx := context.WithValue(context.Background(), "userID", "12345")
	logger.Log(ctx, applogger.Info, "User logged in")
}

HTTP Logging

logger.LogHTTP(context.Background(), applogger.Info, "GET /api/user successful", 200, 0.125)

Fatal Logging (Exits Application)

logger.Log(context.Background(), applogger.Fatal, "Critical system failure!")

📝 License

This project is licensed under the MIT License. See the LICENSE file for details.

Authors

• Iordanis Paschalidis -junkd0g