Merge pull request #34 from Chia-Network/slogs

Add slog structured logging wrapper package

.gitignore

@@ -1,2 +1,3 @@
 main
 /bin/
+.idea

pkg/slogs/README.md

@@ -0,0 +1,63 @@
+# slogs
+
+This is a wrapper around the stdlib Golang slog package that just creates a slog logger in some standard way, with a configurable log level.
+
+Slog was introduced in Go 1.21, so that is the minimum required Go version to use this module.
+
+## Usage
+
+```go
+package main
+
+import "github.com/chia-network/go-modules/pkg/slogs"
+
+func main() {
+	// Init the logger with a log-level string (debug, info, warn, error)
+	// defaults to "info" if empty or unsupported string 
+	slogs.Init("info")
+
+	// Logs a hello world message at the info level
+	slogs.Logger.Info("hello world")
+
+	// Logs an error message at the error level 
+	slogs.Logger.Error("we received an error")
+}
+```
+
+In a Cobra/Viper CLI app this might look more like:
+
+```go
+package cmd
+
+import (
+	"log"
+
+	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
+	"github.com/chia-network/go-modules/pkg/slogs"
+)
+
+var rootCmd = &cobra.Command{
+	Use:   "cmd",
+	Short: "Short help message for cmd",
+
+	Run: func(cmd *cobra.Command, args []string) {
+		// Init logger
+		slogs.Init(viper.GetString("log-level"))
+
+		// Application logic below
+	},
+}
+
+func Execute() {
+	cobra.CheckErr(rootCmd.Execute())
+}
+
+func init() {
+	rootCmd.PersistentFlags().String("log-level", "info", "The log-level for the application, can be one of info, warn, error, debug.")
+	err := viper.BindPFlag("log-level", rootCmd.PersistentFlags().Lookup("log-level"))
+	if err != nil {
+		log.Fatalln(err.Error()) // Have to log with standard logger until the slog logger is initialized
+	}
+}
+```

pkg/slogs/slogs.go

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+package slogs
+
+import (
+	"log"
+	"log/slog"
+	"os"
+	"strings"
+)
+
+// Logger is a custom text logger from the stdlib slog package
+var Logger *slog.Logger
+
+// Init custom init function that accepts the log level for the application and initializes a stdout slog logger
+func Init(level string) {
+	Logger = slog.New(
+		slog.NewTextHandler(
+			os.Stdout,
+			&slog.HandlerOptions{
+				Level: parseLogLevel(level),
+			},
+		),
+	)
+}
+
+// Function to convert log level string to slog.Level
+func parseLogLevel(level string) slog.Level {
+	switch strings.ToLower(level) {
+	case "debug":
+		return slog.LevelDebug
+	case "info":
+		return slog.LevelInfo
+	case "warn", "warning":
+		return slog.LevelWarn
+	case "error":
+		return slog.LevelError
+	default:
+		log.Printf("unknown log level specified \"%s\", defaulting to info level", level)
+		return slog.LevelInfo
+	}
+}