logger

logger

logger is a Go library providing structured logging with support for development and production environments, including Google Cloud Logging integration.

Overview

This package simplifies logging in Go applications by providing a unified interface for both development and production environments. In development, logs are printed to the console in a human-readable format with colors and timestamps. In production, logs are sent to Google Cloud Logging with structured data.

Features

• Easy setup for both development and production logging.
• Structured logging with key-value pairs.
• Supports log levels (DEBUG, INFO, WARN, ERROR).
• Colorful console output in development.
• Integration with Google Cloud Logging.
• Error stack traces in development mode for easier debugging.

Installation

go get github.com/albeebe/service/pkg/logger

Usage

Setting up Development Logging

package main

import (
    "context"
    "log/slog"

    "github.com/albeebe/service/pkg/logger"
)

func main() {
    ctx := context.Background()

    config := logger.Config{
        Level: slog.LevelDebug, // Set desired log level
    }

    log, err := logger.NewDevelopmentLogger(ctx, config)
    if err != nil {
        panic(err)
    }

    // Use the logger
    log.Info("Application started", "version", "1.0.0")
    log.Debug("Debugging info", "details", "some debug info")
    log.Error("An error occurred", "error", err)
}

Setting up Google Cloud Logging

package main

import (
    "context"
    "log/slog"

    "github.com/albeebe/service/pkg/logger"
)

func main() {
    ctx := context.Background()

    config := logger.Config{
        GCPProjectID: "your-gcp-project-id",
        LogName:      "your-log-name",
        Level:        slog.LevelInfo, // Set desired log level
    }

    log, err := logger.NewGoogleCloudLogger(ctx, config)
    if err != nil {
        panic(err)
    }

    // Use the logger
    log.Info("Application started", "version", "1.0.0")
    log.Warn("Potential issue detected", "details", "some warning")
    log.Error("An error occurred", "error", err)
}

Configuration

Config Struct

The Config struct is used to configure the logger:

type Config struct {
    GCPProjectID string     // Google Cloud Project ID
    LogName      string     // Name of the log stream
    Level        slog.Level // Minimum log level to capture (e.g., DEBUG, INFO)
}

• GCPProjectID: Required for Google Cloud Logging; specify your Google Cloud Project ID.
• LogName: Required for Google Cloud Logging; specify the name of the log stream.
• Level: Sets the minimum level of logs to capture.

Logging Levels

The logger supports the following log levels:

• slog.LevelDebug: Debug-level messages, typically only of interest during development.
• slog.LevelInfo: Informational messages that highlight the progress of the application.
• slog.LevelWarn: Potentially harmful situations which still allow the application to continue running.
• slog.LevelError: Error events that might still allow the application to continue running.

Flushing Logs

For production logging to Google Cloud, it's important to flush the logs before exiting the application to ensure all logs are properly sent.

if err := logger.FlushLogger(log); err != nil {
    panic(err)
}

Examples

Logging with Structured Data

You can include key-value pairs in your log messages:

log.Info("User login", "username", "johndoe", "method", "oauth")

Error Logging with Stack Trace (Development Mode)

In development mode, when logging errors, a stack trace is included to help with debugging:

err := errors.New("something went wrong")
log.Error("an error occurred", "error", err)

Outputs:

[11:10:53.442] [ERROR] something went wrong | error=an error occurred
   └── (file: /path/to/project/service/main.go, line: 86)
   └── (file: /path/to/project/service-demo/main.go, line: 61)

This will output the error message along with a stack trace showing the file and line numbers.

Prerequisites

Google Cloud Logging

To use Google Cloud Logging, you need:

• A Google Cloud Platform project.
• Proper authentication setup (e.g., service account with the Logging > Logs Writer role).
• Application credentials configured in your environment (e.g., GOOGLE_APPLICATION_CREDENTIALS environment variable pointing to your service account key file).

License

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

Contributing

Contributions are welcome! Feel free to open an issue or submit a pull request with any proposed changes.