♲ Refactor configuration to use viper with context propagation

- Replace global ConfigPath and Overrides with viper-based configuration
- Add viper.New() to create configurable viper instances
- Store viper and unmarshaled Config struct in context for testability
- Add RetrieveFromContext and AddToContext helper functions
- Update files.Append to accept context and retrieve config from it
- Update formatters.Preferred and formatters.New to accept context
- Add PersistentPreRunE in CLI to create and configure viper instance
- Support -c flag for custom config file path
- Support -v flag for config value overrides
- Update all test files to create viper and add to context
- Remove unused config types and load functions
- Add viper as dependency with automatic env var support (MYLOG_*)

cli/root.go

@@ -1,5 +1,5 @@
 /*
-Copyright © 2024 Dan Jones <danjones@goodevilgenius.org>
+Copyright © 2026 Dan Jones <danjones@goodevilgenius.org>
 
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU Affero General Public License as published by
@@ -17,6 +17,7 @@ along with this program. If not, see <http://www.gnu.org/licenses/>.
 package cli
 
 import (
+	"context"
 	"os"
 
 	"codeberg.org/danjones000/my-log/config"
@@ -26,16 +27,41 @@ import (
 var RootCmd = &cobra.Command{
 	Use:   "my-log",
 	Short: "A brief description of your application",
+	PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
+		ctx, v, err := config.New(cmd.Context())
+		if err != nil {
+			return err
+		}
+
+		if configPath != "" {
+			v.SetConfigFile(configPath)
+			err := v.ReadInConfig()
+			if err != nil {
+				return err
+			}
+		}
+
+		for k, val := range configValues {
+			v.Set(k, val)
+		}
+
+		cmd.SetContext(ctx)
+
+		return nil
+	},
 }
 
-func Execute() {
-	err := RootCmd.Execute()
+func Execute(ctx context.Context) {
+	err := RootCmd.ExecuteContext(ctx)
 	if err != nil {
 		os.Exit(1)
 	}
 }
 
+var configPath string
+var configValues map[string]string
+
 func init() {
-	RootCmd.PersistentFlags().StringVarP(&config.ConfigPath, "config", "c", config.ConfigPath, "config file")
-	RootCmd.PersistentFlags().StringToStringVarP(&config.Overrides, "config-value", "v", config.Overrides, "Override config values. Use dot syntax to specify key. E.g. -v output.stdout.config.format=json")
+	RootCmd.PersistentFlags().StringVarP(&configPath, "config", "c", config.DefaultPath(), "config file")
+	RootCmd.PersistentFlags().StringToStringVarP(&configValues, "config-value", "v", nil, "Override config values. Use dot syntax to specify key. E.g. -v output.stdout.config.format=json")
 }