Read user defaults before command execution

Author: Moritz Clasmeier

cmd/main.go

@@ -1,12 +1,16 @@
 package main
 
 import (
+	"fmt"
 	"os"
 
+	"dario.cat/mergo"
 	"github.com/fatih/color"
 	"github.com/spf13/cobra"
 	"github.com/stackrox/roxie/internal/deployer"
 	"github.com/stackrox/roxie/internal/logger"
+	"github.com/stackrox/roxie/internal/xdg"
+	"gopkg.in/yaml.v3"
 )
 
 var (
@@ -23,13 +27,50 @@ var (
 )
 
 func main() {
-	if err := rootCmd.Execute(); err != nil {
-		red := color.New(color.FgRed, color.Bold)
+	globalLogger = logger.New()
+	red := color.New(color.FgRed, color.Bold)
+	if err := run(); err != nil {
 		red.Fprintf(os.Stderr, "Error: %v\n", err)
 		os.Exit(1)
 	}
 }
 
+func run() error {
+	if err := tryApplyUserDefaults(globalLogger, &deploySettings); err != nil {
+		return err
+	}
+	return rootCmd.Execute()
+}
+
+// If a user config file exists, apply those user defaults on top the
+// current config. This essentially means, that the user config can
+// override values, which are already initialized in NewConfig().
+// Note: the user config should only contain reasonable fields, which
+// are not already handled by roxies smart defaulting like cluster-dependent
+// resource profiles.
+func tryApplyUserDefaults(log *logger.Logger, config *deployer.Config) error {
+	path, err := xdg.UserConfigPath()
+	if err != nil {
+		return nil
+	}
+	data, err := os.ReadFile(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+		return fmt.Errorf("reading user config %q: %w", path, err)
+	}
+	var userDefaults deployer.Config
+	if err := yaml.Unmarshal(data, &userDefaults); err != nil {
+		return fmt.Errorf("parsing user config %q: %w", path, err)
+	}
+	if err := mergo.Merge(config, &userDefaults, mergo.WithOverride, mergo.WithoutDereference); err != nil {
+		return fmt.Errorf("merging user config %q: %w", path, err)
+	}
+	log.Dimf("Applied user config from %s", path)
+	return nil
+}
+
 var rootCmd = &cobra.Command{
 	Use:   "roxie",
 	Short: "roxie - Advanced Cluster Security Deployment Tool",