GoogleContainerTools/skaffold · error

docker build failure

Error message

docker build failure: %w

What it means

While streaming the build's JSON messages, a *jsonstream.Error was received — the daemon reported the build itself failed (e.g. a RUN command exited non-zero). Skaffold detects the error type via errors.As and rewraps it as `docker build failure` to distinguish a real build failure from a transport problem.

Solutions

1. Read the wrapped jsonstream error output to find the failing Dockerfile step
2. Fix the failing instruction in the Dockerfile
3. Rebuild with --no-cache if a cached layer masks the issue
4. Check base image names/tags and registry authentication

Example fix

// before
RUN npm test   # failing step
// after
RUN npm run build   # corrected/removed failing step

var jm *jsonstream.Error
if err := ...; errors.As(err, &jm) {
	// inspect jm for the failing Dockerfile step and fix the Dockerfile
	return fmt.Errorf("build step failed: %v", jm)
}

When it happens

Trigger: streamDockerMessages returns a *jsonstream.Error, i.e. the Docker daemon sent an error message during the build — a failing RUN/COPY step, exit code != 0 in a Dockerfile instruction, or a step the daemon could not execute.

Common situations: Dockerfile bug (typo in package name, failing test in RUN); missing base image or registry auth; COPY of a file excluded by .dockerignore; disk full on the daemon host.

Related errors

• normalizing dockerfile path
• normalizing dockerfile path
• normalizing dockerfilePath path
• reading dockerfile
• removing unused default args

AI-assisted analysis of GoogleContainerTools/skaffold@a1189de023 (2026-09-05). Data as JSON: /api/errors/c31053a2caa0c27a. Report an issue: GitHub.

Appendix: source

Thrown at pkg/skaffold/docker/image.go:402

	var imageID string
	auxCallback := func(msg jsonstream.Message) {
		if msg.Aux == nil {
			return
		}

		var result BuildResult
		if err := json.Unmarshal(*msg.Aux, &result); err != nil {
			log.Entry(ctx).Debug("Unable to parse build output:", err)
			return
		}
		imageID = result.ID
	}

	if err := streamDockerMessages(out, resp.Body, auxCallback); err != nil {
		var jm *jsonstream.Error
		if errors.As(err, &jm) {
			return "", fmt.Errorf("docker build failure: %w", err)
		}
		return "", fmt.Errorf("unable to stream build output: %w", err)
	}

	if imageID == "" {
		// Maybe this version of Docker doesn't return the digest of the image
		// that has been built.
		imageID, err = l.ImageID(ctx, opts.Tag)
		if err != nil {
			return "", fmt.Errorf("getting digest: %w", err)
		}
	}

	return imageID, nil
}

// streamDockerMessages streams formatted json output from the docker daemon
func streamDockerMessages(dst io.Writer, src io.Reader, auxCallback func(jsonstream.Message)) error {

View on GitHub (pinned to a1189de023)