log-slack

README

Log-Slack

A Go package for sending logs to Slack via webhooks with different log levels.

Features

• Multiple log levels: Error, Warning, Info, Debug, Trace
• Configurable webhook URLs for each log level
• Formatted logging support (Printf-style)
• Default logger instance
• Thread-safe operations

Log Levels

import (
    "github.com/taigrr/log-slack/log"
)

const (
    LevelError LogLevel = iota
    LevelWarning
    LevelInfo
    LevelDebug
    LevelTrace
)

Usage

Basic Setup

// Create a new logger with a webhook URL
logger := log.New("https://hooks.slack.com/services/...")

// Set log level
logger = logger.WithLevel(log.LevelInfo)

// Set prefix
logger.SetPrefix("[MyApp] ")

// Log messages
logger.Info("This is an info message")
logger.Error("This is an error message")

Using Default Logger

// Configure default logger
log.Default().WithLevel(log.LevelInfo)

// Log messages
log.Info("This is an info message")
log.Errorf("Error occurred: %v", err)

Available Methods

For each log level (Error, Warning, Info, Debug, Trace), the following methods are available:

• Level(message string)
• Levelf(format string, args ...any)
• Levelln(args ...any)

Example:

log.Info("Simple message")
log.Infof("Formatted message: %s", value)
log.Infoln("Message with newline")

Stdlib Compatibility

The package provides all standard library log functions:

log.Print("message")
log.Printf("format %s", "message")
log.Println("message")
log.Fatal("fatal message")  // Exits with status 1
log.Panic("panic message")  // Panics after logging

Configuration

LogWriter

The LogWriter struct allows configuration of different webhook URLs for each log level:

type LogWriter struct {
    Log     string // used by Log/Print/Info-level sends
    Error   string // used by Error/Fatal/Panic sends
    Warning string // used by Warning sends
    Info    string
    Debug   string // used by Debug sends
    Trace   string // used by Trace sends
    Level   LogLevel
}

Each field is the webhook URL for its level. Info/Log messages post to the Log field. When constructed via New, every field is set to the same webhook URL.

Custom Configuration

writer := log.LogWriter{
    Log:   "info-webhook-url",  // Log/Info messages
    Error: "error-webhook-url", // Error messages
    Level: log.LevelInfo,
}
logger := log.Default().WithWriter(writer)

Error Handling

By default, failed Slack posts do not interrupt your program. The most recent send error is recorded on the logger and can be inspected via Err():

logger.Info("message")
if err := logger.Err(); err != nil {
    // Handle error
}

The stored error is sticky: once a send fails, Err() keeps returning that error even after later successful sends, until you reset it with ClearErr():

if logger.Err() != nil {
    logger.ClearErr() // reset after handling
}

All loggers are safe for concurrent use by multiple goroutines.

Notes

• Messages are automatically prefixed with their log level (ERRO, WARN, INFO, DEBG, TRCE)
• The package uses HTTP POST requests to send messages to Slack
• Log levels are hierarchical - setting a level will include all higher priority levels
• Global prefix is prepended to all messages

License

Released under the 0BSD license.