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 sends and as an Info fallback
    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 messages post to the Info field when it is set, then fall back to Log for compatibility. 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.