User/Group Name Resolution and Enhanced Color Logging

distrobuilder/main_incus.go

@@ -265,11 +265,35 @@ func (c *cmdIncus) run(cmd *cobra.Command, args []string, overlayDir string) err
 		imageTargets |= shared.ImageTargetContainer
 	}
 
-	for _, file := range c.global.definition.Files {
+	// Maps symbolic user/group names to their numeric IDs using information from passwd and group files.
+	userMap, groupMap, err := parsePasswdAndGroupFiles(overlayDir)
+	if err != nil {
+		c.global.logger.WithField("overlay", overlayDir).Warn("Could not parse passwd/group file: %w", err)
+	}
+
+	for i, file := range c.global.definition.Files {
 		if !shared.ApplyFilter(&file, c.global.definition.Image.Release, c.global.definition.Image.ArchitectureMapped, c.global.definition.Image.Variant, c.global.definition.Targets.Type, imageTargets) {
 			continue
 		}
 
+		if file.UID != "" && !isNumeric(file.UID) {
+			uid, exists := userMap[file.UID]
+			if exists {
+				c.global.definition.Files[i].UID = uid
+			} else {
+				c.global.logger.WithField("generator", file.Generator).Warnf("Could not find UID for user %q", file.UID)
+			}
+		}
+
+		if file.UID != "" && !isNumeric(file.GID) {
+			gid, exists := groupMap[file.GID]
+			if exists {
+				c.global.definition.Files[i].GID = gid
+			} else {
+				c.global.logger.WithField("generator", file.Generator).Warnf("Could not find GID for group %q", file.GID)
+			}
+		}
+
 		generator, err := generators.Load(file.Generator, c.global.logger, c.global.flagCacheDir, overlayDir, file, *c.global.definition)
 		if err != nil {
 			return fmt.Errorf("Failed to load generator %q: %w", file.Generator, err)

distrobuilder/passwd.go

@@ -0,0 +1,56 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+)
+
+// parsePasswdAndGroupFiles reads passwd and group files from the given root directory
+// and returns mappings of names to IDs for both users and groups.
+func parsePasswdAndGroupFiles(rootDir string) (map[string]string, map[string]string, error) {
+	userMap, err := parsePasswdFile(filepath.Join(rootDir, "/etc/passwd"))
+	if err != nil {
+		return nil, nil, fmt.Errorf("parsing passwd file: %w", err)
+	}
+
+	groupMap, err := parsePasswdFile(filepath.Join(rootDir, "/etc/group"))
+	if err != nil {
+		return nil, nil, fmt.Errorf("parsing group file: %w", err)
+	}
+
+	return userMap, groupMap, nil
+}
+
+// parsePasswdFile reads a passwd-format file and returns a map of names to IDs.
+func parsePasswdFile(path string) (map[string]string, error) {
+	idMap := make(map[string]string)
+
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("reading file %s: %w", path, err)
+	}
+
+	for _, line := range strings.Split(string(data), "\n") {
+		if line == "" {
+			continue
+		}
+
+		fields := strings.Split(line, ":")
+		if len(fields) < 3 {
+			continue
+		}
+
+		idMap[fields[0]] = fields[2]
+	}
+
+	return idMap, nil
+}
+
+// isNumeric is a helper function to check if a string is numeric.
+func isNumeric(s string) bool {
+	_, err := strconv.Atoi(s)
+	return err == nil
+}

shared/logger.go

@@ -17,6 +17,8 @@ func GetLogger(debug bool) (*logrus.Logger, error) {
 		PadLevelText:  true,
 	}
 
+	formatter.EnvironmentOverrideColors = true
+
 	logger.Formatter = &formatter
 
 	if debug {