kubernetes/kops · warning

building yaml: %w

Error message

building yaml: %w

What it means

After parsing all lines into a manifest, run() serializes it with yaml.Marshal (sigs.k8s.io/yaml) for output. A failure here is essentially impossible for this fixed struct in practice, but it is wrapped defensively as 'building yaml' before writing to stdout.

Source

Thrown at pkg/assets/assetdata/tools/cmd/generatefileassets/main.go:107

		if len(tokens) != 2 {
			return fmt.Errorf("unexpected line %q (expected 2 tokens)", line)
		}
		hash := tokens[0]
		name := tokens[1]
		name = removeBadPrefix(name)

		if exclude.Matches(prefix + name) {
			continue
		}
		m.Files = append(m.Files, file{
			Name:   prefix + name,
			SHA256: hash,
		})
	}

	out, err := yaml.Marshal(&m)
	if err != nil {
		return fmt.Errorf("building yaml: %w", err)
	}
	if _, err := os.Stdout.Write(out); err != nil {
		return fmt.Errorf("writing output: %w", err)
	}
	return nil
}

type manifest struct {
	// FileStores []fileStore `json:"filestores,omitempty"`
	Files []file `json:"files,omitempty"`
}

type file struct {
	Name   string `json:"name,omitempty"`
	SHA256 string `json:"sha256,omitempty"`
}

// removeBadPrefix is a hack for some of the older kubernetes sha256sum files,

View on GitHub (pinned to 4c8573c808)

Solutions

1. Rebuild the tool with a clean module cache: go clean -modcache && go build ./pkg/assets/assetdata/tools/cmd/generatefileassets
2. Verify sigs.k8s.io/yaml dependency integrity (go mod verify)
3. Report a bug with the wrapped inner error if it reproduces on a clean build

out, err := yaml.Marshal(&m)
if err != nil {
	// practically unreachable for this struct; report as a toolchain bug
	return fmt.Errorf("building yaml: %w", err)
}

When it happens

Trigger: yaml.Marshal returns an error while converting the manifest struct to YAML — realistically only from an unsupported value or an internal marshaling failure.

Common situations: Virtually never hit by users; if seen it indicates a broken toolchain/dependency build or tampered local source.

Related errors

• error parsing addons or manifest: %v
• error parsing addons: %v
• failed to parse objects: %w
• failed to parse objects: %w
• error parsing %v: %w

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/608936da8fa26488. Report an issue: GitHub.