What causes "required value not set: %s" in GoogleContainerTools/skaffold?

Set the missing field named in the message in skaffold.yaml (the name after 'required value not set:')

required value not set: %s

Error message

required value not set: %s

What it means

Skaffold's yamltags validation processes struct tags to enforce config correctness. A field marked `yaml:"...,required"` must not hold its zero value; requiredTag.Process returns 'required value not set' naming the yaml field name (falling back to the Go field name) when the parsed config leaves it empty.

Source

Thrown at pkg/skaffold/yamltags/tags.go:176

}

type yamlTag interface {
	Load([]string) error
	Process(reflect.Value) error
}

type requiredTag struct {
	Field reflect.StructField
}

func (rt *requiredTag) Load(s []string) error {
	return nil
}

func (rt *requiredTag) Process(val reflect.Value) error {
	if isZeroValue(val) {
		if tags, ok := rt.Field.Tag.Lookup("yaml"); ok {
			return fmt.Errorf("required value not set: %s", strings.Split(tags, ",")[0])
		}
		return fmt.Errorf("required value not set: %s", rt.Field.Name)
	}
	return nil
}

// A program can have many structs, that each have many oneOfSets.
// Each oneOfSet is a map of a oneOf-set name to the set of fields that belong to that oneOf-set
// Only one field in that set may have a non-zero value.

var allOneOfs map[string]map[string]fieldSet

func getOneOfSetsForStruct(structName string) map[string]fieldSet {
	_, ok := allOneOfs[structName]
	if !ok {
		allOneOfs[structName] = map[string]fieldSet{}
	}
	return allOneOfs[structName]

View on GitHub (pinned to a1189de023)

Solutions

Set the missing field named in the message in skaffold.yaml (the name after 'required value not set:')
Run `skaffold config` / check `skaffold.yaml` against `skaffold init` or current schema docs
If the field genuinely has no value, restructure the config rather than passing an empty string
After a Skaffold upgrade, run `skaffold fix` to migrate old configs to the current schema

Example fix

// before (skaffold.yaml)
verify:
  - name: ""          # required value not set: name
// after
verify:
  - name: my-integration-test
    container:
      image: gcr.io/k8s-skaffold/verify-runner

Defensive patterns

Strategy: validation

Validate before calling

// validate skaffold.yaml against the schema before running
func mustSet(m map[string]interface{}, key string) error {
    v, ok := m[key]
    if !ok || v == nil || v == "" {
        return fmt.Errorf("required value not set: %s", key)
    }
    return nil
}

Type guard

func hasNonEmpty(s string) bool { return strings.TrimSpace(s) != "" }

Try / catch

if err := skaffoldCmd.Run(); err != nil {
    if strings.Contains(err.Error(), "required value not set") {
        // extract field name after ':' and prompt user to fill it in skaffold.yaml
    }
}

Prevention

After every Skaffold upgrade, run `skaffold fix` to migrate required fields
Validate skaffold.yaml against the current schema before CI runs
Start from `skaffold init` output rather than hand-writing configs
Grep the error's field name in skaffold.yaml and fill the empty key

When it happens

Trigger: A skaffold.yaml (or any config decoded into yamltags-annotated structs) omits a field whose struct definition carries a `required` yaml tag, or explicitly sets it to the zero value (empty string, 0, nil), then config validation runs.

Common situations: Missing `deploy:` or `build:` subsection keys; a verify/test case without its `name`; copy-pasting an example but deleting a required key; a newly-added required field after upgrading Skaffold so old configs no longer validate.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

AI-assisted analysis of GoogleContainerTools/skaffold@a1189de023 (2026-09-05). Data as JSON: /api/errors/3da57e942386b63b. Report an issue: GitHub.