Writes and verify image

clitools/pkg/controller/osimage/stream.go

@@ -0,0 +1,50 @@
+package osimage
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"time"
+
+	"github.com/klauspost/compress/zstd"
+)
+
+func OpenDecompressedHTTPStream(ctx context.Context, url string, timeout time.Duration) (io.Reader, func() error, error) {
+	if url == "" {
+		return nil, nil, fmt.Errorf("url is required")
+	}
+	if timeout <= 0 {
+		timeout = 30 * time.Minute
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, nil, fmt.Errorf("build request: %w", err)
+	}
+
+	client := &http.Client{Timeout: timeout}
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, nil, fmt.Errorf("http get %q: %w", url, err)
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		resp.Body.Close()
+		return nil, nil, fmt.Errorf("unexpected status: %s", resp.Status)
+	}
+
+	dec, err := zstd.NewReader(resp.Body)
+	if err != nil {
+		resp.Body.Close()
+		return nil, nil, fmt.Errorf("create zstd decoder: %w", err)
+	}
+
+	closeFn := func() error {
+		dec.Close()
+		return resp.Body.Close()
+	}
+
+	return dec, closeFn, nil
+}