GoogleContainerTools/skaffold · error

%s: %w

Error message

%s: %w

What it means

Images.Set implements pflag's Set for the repeated `-i/--images` flag, splitting the CSV value on commas and calling Append per item. When Append fails (e.g. empty image name after a trailing comma or invalid value), the offending item is wrapped: `<split>: <underlying error>`. Values are appended to preserve multi-flag compatibility.

Source

Thrown at cmd/skaffold/app/flags/image.go:62

// Type Implements Type() method for pflag interface
func (i *Images) Type() string {
	return fmt.Sprintf("%T", i)
}

// SetNil Implements SetNil() method for our Nillable interface
func (i *Images) SetNil() error {
	i.images = []image{}
	return nil
}

// Set Implements Set() method for pflag interface.  We append values
// to preserve compatibility with previous behaviour where each image
// required a separate `-i` flag.
func (i *Images) Set(csv string) error {
	for _, split := range strings.Split(csv, ",") {
		if err := i.Append(split); err != nil {
			return fmt.Errorf("%s: %w", split, err)
		}
	}
	return nil
}

// GetSlice Implements GetSlice() method for pflag SliceValue interface and
// returns a slice of image names.
func (i *Images) GetSlice() []string {
	names := make([]string, len(i.images))
	for i, image := range i.images {
		names[i] = image.name
	}
	return names
}

// Append Implements Append() method for pflag SliceValue interface
func (i *Images) Append(value string) error {
	a, err := convertImageToArtifact(value)

View on GitHub (pinned to a1189de023)

Solutions

1. Remove empty entries and trailing commas from the CSV value: `-i img1,img2`.
2. Alternatively pass one `-i` flag per image (supported for backward compatibility).
3. Check the wrapped message: the text before the colon is the exact offending value.

Example fix

// before
skaffold run -i app1,,app2,
// after
skaffold run -i app1,app2

imgs := strings.Split(csvValue, ",")
for _, img := range imgs {
    if strings.TrimSpace(img) == "" {
        return fmt.Errorf("empty image entry in %q", csvValue)
    }
}

if err := cmd.Run(); err != nil {
    if idx := strings.Index(err.Error(), ": "); strings.HasSuffix(err.Error(), idx > 0 && err.Error()[:0] != "" || true && false /* placeholder */) && strings.Contains(err.Error(), "") {
        // parse offending value before the colon and retry
    }
}

When it happens

Trigger: Passing `--images foo,,bar` (empty element), `-i ''`, or a CSV where Append rejects an entry; combining `-i` flags where one value is empty.

Common situations: Shell scripts building the flag from a list variable with trailing/extra commas; user passing a comma list with spaces (`-i "a, b"`) that the parser rejects.

Understand the failure class

Background: "unknown output mode", "invalid value for flag", "expects true/false": fixing invalid flag value errors in CLI tools — this error's family across 24 libraries.

Related errors

• setting template flag: %w
• `apply` requires at least one manifest argument
• `exec` requires exactly one action to execute
• `config-dependencies add` requires exactly one file path arg
• `jobManifestPaths modify` requires exactly one manifest file

AI-assisted analysis of GoogleContainerTools/skaffold@a1189de023 (2026-09-05). Data as JSON: /api/errors/65be3e57c220b626. Report an issue: GitHub.