feat(devops): add ImageManager

Manages image downloads, manifest tracking, and update checking.
Tries sources in priority order (GitHub, CDN).

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

pkg/devops/images.go

@@ -0,0 +1,193 @@
+package devops
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/host-uk/core/pkg/devops/sources"
+)
+
+// ImageManager handles image downloads and updates.
+type ImageManager struct {
+	config   *Config
+	manifest *Manifest
+	sources  []sources.ImageSource
+}
+
+// Manifest tracks installed images.
+type Manifest struct {
+	Images map[string]ImageInfo `json:"images"`
+	path   string
+}
+
+// ImageInfo holds metadata about an installed image.
+type ImageInfo struct {
+	Version    string    `json:"version"`
+	SHA256     string    `json:"sha256,omitempty"`
+	Downloaded time.Time `json:"downloaded"`
+	Source     string    `json:"source"`
+}
+
+// NewImageManager creates a new image manager.
+func NewImageManager(cfg *Config) (*ImageManager, error) {
+	imagesDir, err := ImagesDir()
+	if err != nil {
+		return nil, err
+	}
+
+	// Ensure images directory exists
+	if err := os.MkdirAll(imagesDir, 0755); err != nil {
+		return nil, err
+	}
+
+	// Load or create manifest
+	manifestPath := filepath.Join(imagesDir, "manifest.json")
+	manifest, err := loadManifest(manifestPath)
+	if err != nil {
+		return nil, err
+	}
+
+	// Build source list based on config
+	imageName := ImageName()
+	sourceCfg := sources.SourceConfig{
+		GitHubRepo:    cfg.Images.GitHub.Repo,
+		RegistryImage: cfg.Images.Registry.Image,
+		CDNURL:        cfg.Images.CDN.URL,
+		ImageName:     imageName,
+	}
+
+	var srcs []sources.ImageSource
+	switch cfg.Images.Source {
+	case "github":
+		srcs = []sources.ImageSource{sources.NewGitHubSource(sourceCfg)}
+	case "cdn":
+		srcs = []sources.ImageSource{sources.NewCDNSource(sourceCfg)}
+	default: // "auto"
+		srcs = []sources.ImageSource{
+			sources.NewGitHubSource(sourceCfg),
+			sources.NewCDNSource(sourceCfg),
+		}
+	}
+
+	return &ImageManager{
+		config:   cfg,
+		manifest: manifest,
+		sources:  srcs,
+	}, nil
+}
+
+// IsInstalled checks if the dev image is installed.
+func (m *ImageManager) IsInstalled() bool {
+	path, err := ImagePath()
+	if err != nil {
+		return false
+	}
+	_, err = os.Stat(path)
+	return err == nil
+}
+
+// Install downloads and installs the dev image.
+func (m *ImageManager) Install(ctx context.Context, progress func(downloaded, total int64)) error {
+	imagesDir, err := ImagesDir()
+	if err != nil {
+		return err
+	}
+
+	// Find first available source
+	var src sources.ImageSource
+	for _, s := range m.sources {
+		if s.Available() {
+			src = s
+			break
+		}
+	}
+	if src == nil {
+		return fmt.Errorf("no image source available")
+	}
+
+	// Get version
+	version, err := src.LatestVersion(ctx)
+	if err != nil {
+		return fmt.Errorf("failed to get latest version: %w", err)
+	}
+
+	fmt.Printf("Downloading %s from %s...\n", ImageName(), src.Name())
+
+	// Download
+	if err := src.Download(ctx, imagesDir, progress); err != nil {
+		return err
+	}
+
+	// Update manifest
+	m.manifest.Images[ImageName()] = ImageInfo{
+		Version:    version,
+		Downloaded: time.Now(),
+		Source:     src.Name(),
+	}
+
+	return m.manifest.Save()
+}
+
+// CheckUpdate checks if an update is available.
+func (m *ImageManager) CheckUpdate(ctx context.Context) (current, latest string, hasUpdate bool, err error) {
+	info, ok := m.manifest.Images[ImageName()]
+	if !ok {
+		return "", "", false, fmt.Errorf("image not installed")
+	}
+	current = info.Version
+
+	// Find first available source
+	var src sources.ImageSource
+	for _, s := range m.sources {
+		if s.Available() {
+			src = s
+			break
+		}
+	}
+	if src == nil {
+		return current, "", false, fmt.Errorf("no image source available")
+	}
+
+	latest, err = src.LatestVersion(ctx)
+	if err != nil {
+		return current, "", false, err
+	}
+
+	hasUpdate = current != latest
+	return current, latest, hasUpdate, nil
+}
+
+func loadManifest(path string) (*Manifest, error) {
+	m := &Manifest{
+		Images: make(map[string]ImageInfo),
+		path:   path,
+	}
+
+	data, err := os.ReadFile(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return m, nil
+		}
+		return nil, err
+	}
+
+	if err := json.Unmarshal(data, m); err != nil {
+		return nil, err
+	}
+	m.path = path
+
+	return m, nil
+}
+
+// Save writes the manifest to disk.
+func (m *Manifest) Save() error {
+	data, err := json.MarshalIndent(m, "", "  ")
+	if err != nil {
+		return err
+	}
+	return os.WriteFile(m.path, data, 0644)
+}

pkg/devops/images_test.go

@@ -0,0 +1,32 @@
+package devops
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestImageManager_Good_IsInstalled(t *testing.T) {
+	tmpDir := t.TempDir()
+	t.Setenv("CORE_IMAGES_DIR", tmpDir)
+
+	cfg := DefaultConfig()
+	mgr, err := NewImageManager(cfg)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	// Not installed yet
+	if mgr.IsInstalled() {
+		t.Error("expected IsInstalled() to be false")
+	}
+
+	// Create fake image
+	imagePath := filepath.Join(tmpDir, ImageName())
+	os.WriteFile(imagePath, []byte("fake"), 0644)
+
+	// Now installed
+	if !mgr.IsInstalled() {
+		t.Error("expected IsInstalled() to be true")
+	}
+}