kubernetes/kops · error

building path for %q: %w

Error message

building path for %q: %w

What it means

For gs://, s3://, or azureblob:// URLs the downloader builds a vfs.Path via vfs.Context.BuildVfsPath so the object is fetched with ambient cloud credentials. If the URL doesn't map to a valid VFS path for that scheme, this error wraps the cause.

Source

Thrown at upup/pkg/fi/http.go:109

	defer func() {
		klog.V(2).Infof("Downloading %q took %q", desturl, time.Since(start))
	}()
	klog.V(2).Infof("Downloading %q", desturl)

	algorithm := hashing.HashAlgorithmSHA256
	if hash != nil {
		algorithm = hash.Algorithm
	}
	hasher := algorithm.NewHasher()
	writer := io.MultiWriter(dest, hasher)

	switch u.Scheme {
	case "gs", "s3", "azureblob":
		// vfs resolves the bucket and signs the request with the ambient cloud credentials,
		// such as the instance identity.
		p, err := vfs.Context.BuildVfsPath(desturl)
		if err != nil {
			return nil, fmt.Errorf("building path for %q: %w", desturl, err)
		}
		cloudPath, ok := p.(vfs.WriterToWithContext)
		if !ok {
			return nil, fmt.Errorf("path type %T for %q does not implement WriteToWithContext", p, desturl)
		}
		if _, err := cloudPath.WriteToWithContext(ctx, writer); err != nil {
			return nil, fmt.Errorf("error downloading content from %q: %w", desturl, err)
		}
	default:
		reader, err := OpenURL(desturl)
		if err != nil {
			return nil, err
		}
		defer reader.Close()

		if _, err := io.Copy(writer, reader); err != nil {
			return nil, fmt.Errorf("error downloading HTTP content from %q: %v", desturl, err)
		}

View on GitHub (pinned to 4c8573c808)

Solutions

1. Check the wrapped error for the vfs path-building failure detail
2. Verify the bucket name and region in the URL are correct and the bucket exists
3. Ensure the URL scheme matches your cloud provider setup (s3 on AWS, gs on GCP, azureblob on Azure)
4. Verify cloud credentials are configured for the ambient provider

Example fix

// before
url: "s3://my-bucket-with-a-typo/file.tgz"
// after
url: "s3://my-bucket/file.tgz"

u, _ := url.Parse(assetURL)
switch u.Scheme {
case "s3":
    if _, err := awsConfig.Credentials.Retrieve(ctx); err != nil {
        return fmt.Errorf("AWS credentials required for %s: %w", assetURL, err)
    }
case "gs", "azureblob":
    return fmt.Errorf("scheme %s not configured in this environment", u.Scheme)
}

if _, err := fi.DownloadURL(ctx, assetURL, dest, nil); err != nil {
    if strings.Contains(err.Error(), "building path for") {
        return fmt.Errorf("check bucket name/region and provider for %s: %w", assetURL, err)
    }
    return err
}

When it happens

Trigger: BuildVfsPath fails for a cloud-storage URL: wrong bucket name, unsupported location/region string, or scheme configured but cloud provider not enabled in the build.

Common situations: Typo in bucket name in a mirrored asset URL; using gs:// URLs while running on a non-GCP build/config; bucket in an unsupported region.

Related errors

• error downloading file %q: %v
• path type %T for %q does not implement WriteToWithContext
• error downloading content from %q: %w
• ReadOnlyError
• error reading addons from %q: %v

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/11db5cc5d1dccfaa. Report an issue: GitHub.