OSUpgrade: Version Planning

clitools/pkg/catalog/resolver.go

@@ -0,0 +1,113 @@
+package catalog
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+
+	"sigs.k8s.io/yaml"
+
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/client-go/kubernetes"
+
+	monov1alpha1 "example.com/monok8s/pkg/apis/monok8s/v1alpha1"
+)
+
+const (
+	DefaultCachePath = "/var/lib/monok8s/catalog.yaml"
+)
+
+// ResolveCatalog resolves catalog using priority:
+// Inline > ConfigMap > URL > cached
+func ResolveCatalog(
+	ctx context.Context,
+	kubeClient kubernetes.Interface,
+	namespace string,
+	src *monov1alpha1.VersionCatalogSource,
+) (*VersionCatalog, error) {
+
+	// 1. Inline
+	if src != nil && src.Inline != "" {
+		return parseCatalog([]byte(src.Inline))
+	}
+
+	// 2. ConfigMap
+	if src != nil && src.ConfigMap != "" {
+		cm, err := kubeClient.CoreV1().ConfigMaps(namespace).Get(ctx, src.ConfigMap, metav1.GetOptions{})
+		if err != nil {
+			return nil, fmt.Errorf("get catalog configmap: %w", err)
+		}
+
+		data, ok := cm.Data["catalog.yaml"]
+		if !ok {
+			return nil, fmt.Errorf("configmap %s missing key catalog.yaml", src.ConfigMap)
+		}
+
+		return parseCatalog([]byte(data))
+	}
+
+	// 3. URL
+	if src != nil && src.URL != "" {
+		cat, err := fetchCatalog(src.URL)
+		if err == nil {
+			_ = os.WriteFile(DefaultCachePath, mustMarshal(cat), 0644)
+			return cat, nil
+		}
+
+		// fallback to cache
+		if cached, err2 := loadCached(); err2 == nil {
+			return cached, nil
+		}
+
+		return nil, fmt.Errorf("fetch catalog failed and no cache: %w", err)
+	}
+
+	// 4. cached fallback
+	if cached, err := loadCached(); err == nil {
+		return cached, nil
+	}
+
+	return nil, fmt.Errorf("no catalog source available")
+}
+
+func fetchCatalog(url string) (*VersionCatalog, error) {
+	resp, err := http.Get(url)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != 200 {
+		return nil, fmt.Errorf("http %d", resp.StatusCode)
+	}
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	return parseCatalog(body)
+}
+
+func loadCached() (*VersionCatalog, error) {
+	data, err := os.ReadFile(DefaultCachePath)
+	if err != nil {
+		return nil, err
+	}
+	return parseCatalog(data)
+}
+
+func parseCatalog(data []byte) (*VersionCatalog, error) {
+	var c VersionCatalog
+	if err := yaml.Unmarshal(data, &c); err != nil {
+		return nil, fmt.Errorf("parse catalog: %w", err)
+	}
+	return &c, nil
+}
+
+func mustMarshal(c *VersionCatalog) []byte {
+	b, _ := yaml.Marshal(c)
+	return b
+}