schemas/logging/log.go

package logging

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

	"go.opentelemetry.io/contrib/bridges/otelslog"
)

type Logger interface {
	Info(msg string, args ...any)
	Warn(msg string, args ...any)
	Error(msg string, args ...any)
}

var defaultLogger *slog.Logger

type contextKey string

const loggerKey = contextKey("logger")

func SetupLogger(logLevel, logFormat, serviceName, buildVersion string) *slog.Logger {
	var leveler slog.LevelVar

	err := leveler.UnmarshalText([]byte(logLevel))

	handlerOpts := &slog.HandlerOptions{
		AddSource:   false,
		Level:       leveler.Level(),
		ReplaceAttr: nil,
	}

	var handler slog.Handler
	switch logFormat {
	case "json":
		handler = slog.NewJSONHandler(os.Stdout, handlerOpts)
	case "text":
		handler = slog.NewTextHandler(os.Stdout, handlerOpts)
	case "otel":
		handler = otelslog.NewHandler(serviceName,
			otelslog.WithVersion(buildVersion))
	}
	defaultLogger = slog.New(handler).With("service", serviceName).With("version", buildVersion)
	if err != nil {
		defaultLogger.With("err", err).Error("Failed to parse log level")
		os.Exit(1)
	}
	slog.SetDefault(defaultLogger)
	return defaultLogger
}

// ContextWithLogger returns a new Context with the logger attached
func ContextWithLogger(ctx context.Context, logger *slog.Logger) context.Context {
	return context.WithValue(ctx, loggerKey, logger)
}

// LoggerFromContext returns a logger from the passed context or the default logger
func LoggerFromContext(ctx context.Context) *slog.Logger {
	logger := ctx.Value(loggerKey)
	if l, ok := logger.(*slog.Logger); ok {
		return l
	}
	return defaultLogger
}