Initial commit.

internal/application/logger.go

@@ -0,0 +1,45 @@
+package application
+
+import (
+	"log/slog"
+	"os"
+	"strings"
+)
+
+const (
+	defaultLogLevel slog.Level = slog.LevelInfo
+
+	logLevelEnvVar = "VN_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 ...any) *slog.Logger {
+	return a.baseLogger.With(withs...)
+}