GoogleContainerTools/skaffold · error

parsing ONBUILD instructions: %w

Error message

parsing ONBUILD instructions: %w

What it means

Fires in expandOnbuildInstructions when the ONBUILD triggers inherited from a base image cannot be parsed. Skaffold fetches base-image ONBUILD instructions (from the local daemon or remote registry) and re-parses them as Dockerfile AST nodes to track COPY dependencies; failure means the base image's ONBUILD commands were not parseable.

Source

Thrown at pkg/skaffold/docker/parse.go:398

			from := fromInstruction(node)

			// onbuild should immediately follow the from command
			expandedNodes = append(expandedNodes, nodes[n:m+1]...)
			n = m + 1

			var onbuildNodes []*parser.Node
			if ons, found := onbuildNodesCache[strings.ToLower(from.image)]; found {
				onbuildNodes = ons
			} else if from.image == "" {
				// some build args like artifact dependencies are not available until the first build sequence has completed.
				// skip check if there are unavailable images
				onbuildNodes = []*parser.Node{}
			} else if ons, err := parseOnbuild(ctx, from.image, cfg); err == nil {
				onbuildNodes = ons
			} else if warnMsg, ok, _ := isOldImageManifestProblem(cfg, err); ok && warnMsg != "" {
				log.Entry(context.TODO()).Warn(warnMsg)
			} else if !ok {
				return nil, fmt.Errorf("parsing ONBUILD instructions: %w", err)
			}

			// Stage names are case insensitive
			onbuildNodesCache[strings.ToLower(from.as)] = nodes
			onbuildNodesCache[strings.ToLower(from.image)] = nodes

			expandedNodes = append(expandedNodes, onbuildNodes...)
		}
	}
	expandedNodes = append(expandedNodes, nodes[n:]...)

	return expandedNodes, nil
}

func parseOnbuild(ctx context.Context, image string, cfg Config) ([]*parser.Node, error) {
	log.Entry(context.TODO()).Tracef("Checking base image %s for ONBUILD triggers.", image)

	// Image names are case SENSITIVE

View on GitHub (pinned to a1189de023)

Solutions

1. Pull the base image again (docker pull <base>) to ensure a complete, uncorrupted manifest
2. Use a base image with simpler/valid ONBUILD instructions or avoid ONBUILD-based COPY triggers
3. Report to skaffold maintainers if the base image is valid and the failure persists

When it happens

Trigger: Thrown at pkg/skaffold/docker/parse.go:398 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of GoogleContainerTools/skaffold@a1189de023 (2026-09-05). Data as JSON: /api/errors/b409043b6427a80c. Report an issue: GitHub.