GoogleContainerTools/skaffold · error

listing copied files: %w

Error message

listing copied files: %w

What it means

extractCopyCommands walked the parsed (and OnBuild-expanded) instruction list to determine which files each COPY/ADD pulls in; when that fails — e.g. a stage referenced in COPY --from does not exist, or the instruction cannot be resolved against the build context — ReadCopyCmdsFromDockerfile wraps the failure with 'listing copied files'. Dependency computation aborts because the set of copied files cannot be determined.

Source

Thrown at pkg/skaffold/docker/parse.go:114

	if err := validateParsedDockerfile(bytes.NewReader(r), res); err != nil {
		return nil, fmt.Errorf("parsing dockerfile %q: %w", absDockerfilePath, err)
	}

	dockerfileLines := res.AST.Children

	if err := expandBuildArgs(dockerfileLines, buildArgs); err != nil {
		return nil, fmt.Errorf("putting build arguments: %w", err)
	}

	dockerfileLinesWithOnbuild, err := expandOnbuildInstructions(ctx, dockerfileLines, cfg)
	if err != nil {
		return nil, err
	}

	cpCmds, err := extractCopyCommands(ctx, dockerfileLinesWithOnbuild, onlyLastImage, cfg)
	if err != nil {
		return nil, fmt.Errorf("listing copied files: %w", err)
	}

	return expandSrcGlobPatterns(workspace, cpCmds)
}

func ExtractOnlyCopyCommands(absDockerfilePath string) ([]FromTo, error) {
	r, err := os.ReadFile(absDockerfilePath)
	if err != nil {
		return nil, err
	}

	res, err := parser.Parse(bytes.NewReader(r))
	if err != nil {
		return nil, fmt.Errorf("parsing dockerfile %q: %w", absDockerfilePath, err)
	}

	var copied []FromTo
	workdir := "/"

View on GitHub (pinned to a1189de023)

Solutions

1. Ensure every COPY --from=<name> references a stage defined by an earlier FROM in the same Dockerfile
2. Give each stage an explicit unique 'FROM image AS name' and fix typos in stage names
3. Test with 'docker build .' — if docker itself rejects the stage reference, fix it the same way
4. If the error comes from an ONBUILD parent image, inspect that image's Dockerfile history (docker inspect) and adjust your context accordingly

Example fix

// before
FROM golang AS build
FROM alpine
COPY --from=buildr /app/bin /bin
// after
FROM golang AS build
FROM alpine
COPY --from=build /app/bin /bin

func validateCopyFromStages(dockerfilePath string) error {
    stages := map[string]bool{}
    lines := readLines(dockerfilePath)
    for _, l := range lines {
        if m := fromStageRe.FindStringSubmatch(l); m != nil {
            stages[strings.ToLower(m[1])] = true
        }
        if m := copyFromRe.FindStringSubmatch(l); m != nil && !stages[strings.ToLower(m[1])] {
            return fmt.Errorf("COPY --from=%q references undefined stage", m[1])
        }
    }
    return nil
}

func stageDefined(dockerfileContent, stage string) bool {
    re := regexp.MustCompile(`(?i)^FROM\s+\S+\s+AS\s+(\S+)`)
    for _, l := range strings.Split(dockerfileContent, "\n") {
        if m := re.FindStringSubmatch(l); m != nil && strings.EqualFold(m[1], stage) {
            return true
        }
    }
    return false
}

fts, err := skaffold.ReadCopyCmdsFromDockerfile(path, args, cfg, false)
if err != nil && strings.Contains(err.Error(), "listing copied files") {
    return fmt.Errorf("check COPY --from stage names and FROM ordering: %w", err)
}

When it happens

Trigger: ReadCopyCmdsFromDockerfile invoked on a Dockerfile whose COPY --from=<stage> references a nonexistent stage, whose multi-stage FROM names are duplicated/invalid, or where an instruction needed for copy extraction is malformed after build-arg/ONBUILD expansion.

Common situations: Renaming a build stage but forgetting to update COPY --from references; ONBUILD parent images introducing COPY instructions that reference missing context; complex multi-stage files where a stage is referenced before it is defined.

Related errors

• normalizing dockerfile path: %w
• reading dockerfile: %w
• removing unused default args: %w
• normalizing dockerfilePath path: %w
• docker build failure: %w

AI-assisted analysis of GoogleContainerTools/skaffold@a1189de023 (2026-09-05). Data as JSON: /api/errors/15781ae0506cca04. Report an issue: GitHub.