Table of contents

• go-tlog
  • Features
  • Installation
  • Quick start
  • Configuration
    • type Opts
    • Main API
  • Log levels
  • Stacktraces
    • Overriding stacktrace level
  • Output formats
  • Output destinations
  • Examples
  • Testing
  • License

go-tlog

go-tlog is a lightweight and configurable logging library for Go applications.
It provides structured logging with multiple output destinations, flexible formatting, and fine-grained log-level control.

---

Features

• Simple setup via configuration struct
• Text or JSON output formats
• Multiple output targets: stdout, stderr, files
• Log levels: Trace, Debug, Info, Warn, Error
• Automatic timestamp, source file, and line number
• Automatic stacktraces based on log level

---

Installation

go get github.com/tarantool/go-tlog@latest

Then import:

import "github.com/tarantool/go-tlog"

---

Quick start

package main

import "github.com/tarantool/go-tlog"

func main() {
	log, err := tlog.New(tlog.Opts{
		Level:  tlog.LevelInfo,
		Format: tlog.FormatText,
		Path:   "stdout",
	})
	if err != nil {
		panic(err)
	}
	defer log.Close()

	logger := log.Logger().With(slog.String("component", "demo"))
	logger.Info("service started", "port", 8080)
	logger.Error("failed to connect", "err", "timeout")
}

Output:

2025-11-10T13:30:01+05:00 INFO service started component=demo port=8080
2025-11-10T13:30:01+05:00 ERROR failed to connect err=timeout component=demo stacktrace="..."

---

Configuration

type Opts

type Opts struct {
    Level  Level  // minimal log level
    Format Format // FormatText or FormatJSON
    Path   string // comma-separated outputs: "stdout,/var/log/app.log"
}

Main API

Function	Description
tlog.New(opts)	Create a new logger
Logger()	Return the underlying logger for use
Close()	Flush buffers and close file descriptors

---

Log levels

Level	When to use
Trace	Low-level tracing
Debug	Debugging information
Info	Normal operational messages
Warn	Non-fatal warnings
Error	Errors and exceptions (includes stacktrace)

---

Stacktraces

go-tlog can automatically attach stacktraces to log records.

By default, the stacktrace threshold is the same as the configured log level. This means that stacktraces are added starting from the current log level and for all higher-severity messages.

The default behavior is:

Log level	Stacktrace is added for
Trace	DEBUG, INFO, WARN, ERROR
Debug	DEBUG, INFO, WARN, ERROR
Info	INFO, WARN, ERROR
Warn	WARN, ERROR
Error	ERROR

You can override this behavior using StacktraceLevel to control the stacktrace threshold independently of the log level.

Overriding stacktrace level

log, err := tlog.New(tlog.Opts{
    Level:           tlog.LevelInfo,
    StacktraceLevel: tlog.LevelError,
    Format:          tlog.FormatText,
    Path:            "stdout",
})

---

Output formats

Format	Example
FormatText	2025-11-10T13:31:45+05:00 INFO message key=value
FormatJSON	{"time":"...","level":"INFO","msg":"message","key":"value"}

---

Output destinations

You can specify multiple targets separated by commas:

Path: "stdout,/tmp/app.log"

Supported targets:

• stdout
• stderr
• File paths (created automatically if not present)

---

Examples

Included examples:

• ExampleNew_text — basic text logger writing to stdout
• ExampleNew_json — JSON logging
• ExampleNew_multi — logging to multiple destinations (stdout,/tmp/...)

Each example demonstrates different combinations of Path, Format, and Level, including how to log to multiple outputs at the same time.

---

Testing

make test

---

License

BSD 2-Clause License — see LICENSE