wslogger

wslogger is a flexible and modern logging package for Go, supporting structured logs, multiple formats, log rotation, OpenTelemetry context, and more.

Features

Multiple log formats: JSON, text (customizable)
Log levels: Info, Warn, Error, Debug
Context-aware logging (OpenTelemetry support)
Log rotation (via lumberjack)
Color output (optional)
Easy configuration via options

Installation

go get github.com/thiagozs/go-wslogger

Usage

package main

import (
    "context"
    "github.com/thiagozs/go-wslogger"
)

func main() {
    log := wslogger.NewLogger(
        wslogger.WithAppName("MyApp"),
        wslogger.WithColor(true),
        wslogger.WithFormat("[{time}] [{app_name}] [{level}] {message} {extra}"),
    )

    log.Info("App started")
    log.Warn("Warning message", "user", "john")
    log.Errorf("Error: %s", "something failed")
    log.Debugf("Debug value: %d", 42)

    // Logging with context (OpenTelemetry)
    ctx := context.Background()
    log.InfoCtx(ctx, "Info with context")
    log.ErrorCtxf(ctx, "Error with wrap: %w", fmt.Errorf("original error"))
}

API Highlights

Main Methods

Info(args ...any)
Warn(args ...any)
Error(args ...any)
Debug(args ...any)
Infof(format string, args ...any)
Warnf(format string, args ...any)
Errorf(format string, args ...any)
Debugf(format string, args ...any)
InfoCtx(ctx, args ...any)
WarnCtx(ctx, args ...any)
ErrorCtx(ctx, args ...any)
DebugCtx(ctx, args ...any)
InfoCtxf(ctx, format, args...)
WarnCtxf(ctx, format, args...)
ErrorCtxf(ctx, format, args...) (supports %w)
DebugCtxf(ctx, format, args...)

Configuration Options

WithAppName(name string)
WithColor(enabled bool)
WithFormat(format string)
WithJSON(enabled bool)
WithWriter(w io.Writer)
WithRotatingFile(filename string, maxSizeMB, maxBackups, maxAgeDays int, compress bool)
WithSpanAttributes(enabled bool)

Example of Advanced Configuration

log := wslogger.NewLogger(
    wslogger.WithAppName("ServiceX"),
    wslogger.WithColor(false),
    wslogger.WithJSON(true),
    wslogger.WithRotatingFile("service.log", 10, 5, 30, true),
)

Goroutines and callsite reporting

By design it's not possible, in general, to reliably determine the exact source location (file:function:line) where a goroutine was created from inside the goroutine itself. The reliable approach is to capture the callsite at the moment the goroutine is spawned and attach it to subsequent log calls.

This package provides a small helper to do that conveniently:

g := log.WrapGoroutine() — call this in the goroutine creator, then pass g (a *GoroutineLogger) into the goroutine. Inside the goroutine use g.Info(...) / g.Infof(...) etc. The helper captures the creation callsite and automatically appends the goroutine_caller extra to log lines.

Example:

// creator
g := log.WrapGoroutine()
go func(lg *wslogger.GoroutineLogger) {
        defer wg.Done()
        lg.Info("started worker")
}(g)

Notes & limitations:

WrapGoroutine() is best-effort: it tries to locate the go statement and format the callsite as basename:function:line. In some cases (anonymous closures, generated function names) the runtime will expose names like func1; using WrapGoroutine() gives the most reliable, consistent information because it captures the creator location at spawn time.
If you prefer not to change call sites, you can also manually pass "goroutine_caller", "file:func:line" as an extra argument on log calls, but that requires the creator to construct the string.

Versioning and license

Our version numbers follow the semantic versioning specification. You can see the available versions by checking the tags on this repository. For more details about our license model, please take a look at the LICENSE.md file.

2025, thiagozs