GoogleContainerTools/skaffold · error

unable to determine runtime for %q

Error message

unable to determine runtime for %q

What it means

Fires in performContainerTransform when neither a user-specified runtime nor inference from the container/image configuration (entrypoint, env, buildpacks metadata) identifies a known language runtime for the container, so no debug transformer (Go/Delve, Java, Node, Python) can be selected.

Source

Thrown at pkg/skaffold/debug/container.go:170

}

func performContainerTransform(adapter types.ContainerAdapter, config ImageConfiguration, portAlloc PortAllocator) (types.ContainerDebugConfiguration, string, error) {
	log.Entry(context.TODO()).Tracef("Examining container %q with config %v", adapter.GetContainer().Name, config)
	// This approach prioritizes the user-defined runtime specified in the configuration. If the user explicitly defines the runtime, we assume they have a
	// specific intention and want to use that specific transform. If no explicit runtime is specified, the code tries to infer the appropriate transform
	//  based on other indicators in the configuration.
	for transform := range containerTransforms {
		if transform.MatchRuntime(config) {
			return transform.Apply(adapter, config, portAlloc, Protocols)
		}
	}

	for transform := range containerTransforms {
		if transform.IsApplicable(config) {
			return transform.Apply(adapter, config, portAlloc, Protocols)
		}
	}
	return types.ContainerDebugConfiguration{}, "", fmt.Errorf("unable to determine runtime for %q", adapter.GetContainer().Name)
}

View on GitHub (pinned to a1189de023)

Solutions

  1. Set the runtime explicitly for the artifact in skaffold.yaml (e.g. buildpacks runtime or debug runtime override) so inference is unnecessary
  2. Ensure the image carries recognizable metadata (entrypoint, buildpack labels) for runtime detection
  3. Rebuild the image with a builder (buildpacks) that embeds runtime information
Defensive patterns

Strategy: validation

When it happens

Trigger: Thrown at pkg/skaffold/debug/container.go:170 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/287e801d5f1892b4. Report an issue: GitHub.