ctxlog

README

Ctxlog

Small package to embed/fetch logger into the context

Usage:

import (
    "context"
	"github.com/weirdgiraffe/ctxlog"
)

func foo(ctx context.Context) {
    log := ctxlog.From(ctx)
    log.Info("hello")
    bar(ctxlog.Embed(ctx, log.WithField("foo", "foo"))
}

func bar(ctx context.Context) {
    log := ctxlog.From(ctx)
    log.Info("world")
}

Right now only slog is supported, which could be inited as:

log := ctxlog.NewSlog(slog.Default())

But feel free to add whichever logger implementation which fullfils the Logger interface.

Documentation

Overview

Example

package main

import (
	"context"
	"log/slog"
	"os"
	"time"

	"github.com/weirdgiraffe/ctxlog"
)

func main() {
	opts := &slog.HandlerOptions{
		Level: slog.LevelInfo,
		ReplaceAttr: func(groups []string, a slog.Attr) slog.Attr {
			if a.Key == slog.TimeKey {
				return slog.Attr{
					Key:   a.Key,
					Value: slog.TimeValue(time.Date(2025, 2, 11, 0, 0, 0, 0, time.UTC)),
				}
			}
			return a
		},
	}
	logger := slog.New(slog.NewTextHandler(os.Stdout, opts))
	log := ctxlog.NewSlog(logger)
	bgCtx := context.Background()
	log = log.With("example", "main")
	ctx := ctxlog.Embed(bgCtx, log)
	foo(ctx)

}

func foo(ctx context.Context) {
	log := ctxlog.From(ctx)
	ctx = ctxlog.Embed(ctx, log.With("foo", "foo"))
	bar(ctx)
}

func bar(ctx context.Context) {
	log := ctxlog.From(ctx)
	log.Info("Hello, World!")
}

Output:
time=2025-02-11T00:00:00.000Z level=INFO msg="Hello, World!" example=main foo=foo

Index

• func Embed(ctx context.Context, logger Logger) context.Context
• type Level
• type Logger
  • func From(ctx context.Context) Logger
  • func NewSlog(l *slog.Logger) Logger

Examples

• Package

Functions

func Embed

func Embed(ctx context.Context, logger Logger) context.Context

Embed adds the logger to the provided context

Types

type Level

type Level int

const (
	LevelDebug Level = -4
	LevelInfo  Level = 0
	LevelWarn  Level = 4
	LevelError Level = 8
)

type Logger

type Logger interface {
	With(args ...any) Logger
	WithGroup(name string) Logger

	Log(ctx context.Context, level Level, msg string, args ...any)

	Debug(msg string, args ...any)
	Info(msg string, args ...any)
	Warn(msg string, args ...any)
	Error(msg string, args ...any)
}

func From

func From(ctx context.Context) Logger

From returns the logger from the provided context

func NewSlog

func NewSlog(l *slog.Logger) Logger