first commit

bib/internal/distrodef/distrodef.go

@@ -0,0 +1,99 @@
+package distrodef
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"golang.org/x/exp/maps"
+	"gopkg.in/yaml.v3"
+
+	"github.com/hashicorp/go-version"
+)
+
+// ImageDef is a structure containing extra information needed to build an image that cannot be extracted
+// from the container image itself. Currently, this is only the list of packages needed for the installer
+// ISO.
+type ImageDef struct {
+	Packages []string `yaml:"packages"`
+}
+
+func findDistroDef(defDirs []string, distro, wantedVerStr string) (string, error) {
+	var bestFuzzyMatch string
+
+	bestFuzzyVer := &version.Version{}
+	wantedVer, err := version.NewVersion(wantedVerStr)
+	if err != nil {
+		return "", fmt.Errorf("cannot parse wanted version string: %w", err)
+	}
+
+	for _, defDir := range defDirs {
+		// exact match
+		matches, err := filepath.Glob(filepath.Join(defDir, fmt.Sprintf("%s-%s.yaml", distro, wantedVerStr)))
+		if err != nil {
+			return "", err
+		}
+		if len(matches) == 1 {
+			return matches[0], nil
+		}
+
+		// fuzzy match
+		matches, err = filepath.Glob(filepath.Join(defDir, fmt.Sprintf("%s-[0-9]*.yaml", distro)))
+		if err != nil {
+			return "", err
+		}
+		for _, m := range matches {
+			baseNoExt := strings.TrimSuffix(filepath.Base(m), ".yaml")
+			haveVerStr := strings.SplitN(baseNoExt, "-", 2)[1]
+			// this should never error (because of the glob above) but be defensive
+			haveVer, err := version.NewVersion(haveVerStr)
+			if err != nil {
+				return "", fmt.Errorf("cannot parse distro version from %q: %w", m, err)
+			}
+			if wantedVer.Compare(haveVer) >= 0 && haveVer.Compare(bestFuzzyVer) > 0 {
+				bestFuzzyVer = haveVer
+				bestFuzzyMatch = m
+			}
+		}
+	}
+	if bestFuzzyMatch == "" {
+		return "", fmt.Errorf("could not find def file for distro %s-%s", distro, wantedVerStr)
+	}
+
+	return bestFuzzyMatch, nil
+}
+
+func loadFile(defDirs []string, distro, ver string) ([]byte, error) {
+	defPath, err := findDistroDef(defDirs, distro, ver)
+	if err != nil {
+		return nil, err
+	}
+
+	content, err := os.ReadFile(defPath)
+	if err != nil {
+		return nil, fmt.Errorf("could not read def file %s for distro %s-%s: %v", defPath, distro, ver, err)
+	}
+	return content, nil
+}
+
+// Loads a definition file for a given distro and image type
+func LoadImageDef(defDirs []string, distro, ver, it string) (*ImageDef, error) {
+	data, err := loadFile(defDirs, distro, ver)
+	if err != nil {
+		return nil, err
+	}
+
+	var defs map[string]ImageDef
+	if err := yaml.Unmarshal(data, &defs); err != nil {
+		return nil, fmt.Errorf("could not unmarshal def file for distro %s: %v", distro, err)
+	}
+
+	d, ok := defs[it]
+	if !ok {
+		return nil, fmt.Errorf("could not find def for distro %s and image type %s, available types: %s", distro, it, strings.Join(maps.Keys(defs), ", "))
+	}
+
+	return &d, nil
+}
+