bunker/server/internal/application/logger.go

package application

import (
	"log/slog"
	"os"
	"strings"
)

const (
	defaultLogLevel slog.Level = slog.LevelInfo

	logLevelEnvVar = "BUNKERD_LOG_LEVEL"
)

func (a *Application) initializeLogger() {
	logLevel := defaultLogLevel

	logLevelAsString, found := os.LookupEnv(logLevelEnvVar)
	if found {
		switch strings.ToLower(logLevelAsString) {
		case "debug":
			logLevel = slog.LevelDebug
		case "info":
			logLevel = slog.LevelInfo
		case "warn":
			logLevel = slog.LevelWarn
		case "error":
			logLevel = slog.LevelError
		}
	}

	slog.Warn("Setting log level.", "level", logLevel.String())

	a.baseLogger = slog.New(slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{
		AddSource: true,
		Level:     logLevel,
	}))

	a.appLogger = a.baseLogger.With("module", "application")
}

// NewLogger creates new sub-instance of base logger and adds some additional data to it for persistent output.
func (a *Application) NewLogger(withs ...interface{}) *slog.Logger {
	return a.baseLogger.With(withs...)
}