feat(devops): add CDN/S3 source

Downloads core-devops images from custom CDN with progress reporting.

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

pkg/devops/sources/cdn.go

@@ -0,0 +1,111 @@
+package sources
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"path/filepath"
+)
+
+// CDNSource downloads images from a CDN or S3 bucket.
+type CDNSource struct {
+	config SourceConfig
+}
+
+// Compile-time interface check.
+var _ ImageSource = (*CDNSource)(nil)
+
+// NewCDNSource creates a new CDN source.
+func NewCDNSource(cfg SourceConfig) *CDNSource {
+	return &CDNSource{config: cfg}
+}
+
+// Name returns "cdn".
+func (s *CDNSource) Name() string {
+	return "cdn"
+}
+
+// Available checks if CDN URL is configured.
+func (s *CDNSource) Available() bool {
+	return s.config.CDNURL != ""
+}
+
+// LatestVersion fetches version from manifest or returns "latest".
+func (s *CDNSource) LatestVersion(ctx context.Context) (string, error) {
+	// Try to fetch manifest.json for version info
+	url := fmt.Sprintf("%s/manifest.json", s.config.CDNURL)
+	req, err := http.NewRequestWithContext(ctx, "GET", url, nil)
+	if err != nil {
+		return "latest", nil
+	}
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil || resp.StatusCode != 200 {
+		return "latest", nil
+	}
+	defer resp.Body.Close()
+
+	// For now, just return latest - could parse manifest for version
+	return "latest", nil
+}
+
+// Download downloads the image from CDN.
+func (s *CDNSource) Download(ctx context.Context, dest string, progress func(downloaded, total int64)) error {
+	url := fmt.Sprintf("%s/%s", s.config.CDNURL, s.config.ImageName)
+
+	req, err := http.NewRequestWithContext(ctx, "GET", url, nil)
+	if err != nil {
+		return fmt.Errorf("cdn.Download: %w", err)
+	}
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("cdn.Download: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != 200 {
+		return fmt.Errorf("cdn.Download: HTTP %d", resp.StatusCode)
+	}
+
+	// Ensure dest directory exists
+	if err := os.MkdirAll(dest, 0755); err != nil {
+		return fmt.Errorf("cdn.Download: %w", err)
+	}
+
+	// Create destination file
+	destPath := filepath.Join(dest, s.config.ImageName)
+	f, err := os.Create(destPath)
+	if err != nil {
+		return fmt.Errorf("cdn.Download: %w", err)
+	}
+	defer f.Close()
+
+	// Copy with progress
+	total := resp.ContentLength
+	var downloaded int64
+
+	buf := make([]byte, 32*1024)
+	for {
+		n, err := resp.Body.Read(buf)
+		if n > 0 {
+			if _, werr := f.Write(buf[:n]); werr != nil {
+				return fmt.Errorf("cdn.Download: %w", werr)
+			}
+			downloaded += int64(n)
+			if progress != nil {
+				progress(downloaded, total)
+			}
+		}
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			return fmt.Errorf("cdn.Download: %w", err)
+		}
+	}
+
+	return nil
+}

pkg/devops/sources/cdn_test.go

@@ -0,0 +1,31 @@
+package sources
+
+import (
+	"testing"
+)
+
+func TestCDNSource_Good_Available(t *testing.T) {
+	src := NewCDNSource(SourceConfig{
+		CDNURL:    "https://images.example.com",
+		ImageName: "core-devops-darwin-arm64.qcow2",
+	})
+
+	if src.Name() != "cdn" {
+		t.Errorf("expected name 'cdn', got %q", src.Name())
+	}
+
+	// CDN is available if URL is configured
+	if !src.Available() {
+		t.Error("expected Available() to be true when URL is set")
+	}
+}
+
+func TestCDNSource_Bad_NoURL(t *testing.T) {
+	src := NewCDNSource(SourceConfig{
+		ImageName: "core-devops-darwin-arm64.qcow2",
+	})
+
+	if src.Available() {
+		t.Error("expected Available() to be false when URL is empty")
+	}
+}