What causes "invalid bind source, source cannot be empty" in docker/cli?

Add an absolute host path as source, e.g. source: /srv/app/config.

invalid bind source, source cannot be empty

Error message

invalid bind source, source cannot be empty

What it means

Raised at the top of handleBindToMount when a mount of type 'bind' has an empty source. A bind mount maps a host path into the container, so the source path is mandatory; unlike type: volume there is no anonymous form, and the converter fails before contacting the engine.

Source

Thrown at cli/compose/convert/volume.go:124

	if volume.Tmpfs != nil {
		return mount.Mount{}, errors.New("tmpfs options are incompatible with type image")
	}
	if volume.Cluster != nil {
		return mount.Mount{}, errors.New("cluster options are incompatible with type image")
	}
	if volume.Image != nil {
		result.ImageOptions = &mount.ImageOptions{
			Subpath: volume.Image.Subpath,
		}
	}
	return result, nil
}

func handleBindToMount(volume composetypes.ServiceVolumeConfig) (mount.Mount, error) {
	result := createMountFromVolume(volume)

	if volume.Source == "" {
		return mount.Mount{}, errors.New("invalid bind source, source cannot be empty")
	}
	if volume.Volume != nil {
		return mount.Mount{}, errors.New("volume options are incompatible with type bind")
	}
	if volume.Image != nil {
		return mount.Mount{}, errors.New("image options are incompatible with type bind")
	}
	if volume.Tmpfs != nil {
		return mount.Mount{}, errors.New("tmpfs options are incompatible with type bind")
	}
	if volume.Cluster != nil {
		return mount.Mount{}, errors.New("cluster options are incompatible with type bind")
	}
	if volume.Bind != nil {
		result.BindOptions = &mount.BindOptions{
			Propagation: mount.Propagation(volume.Bind.Propagation),
		}
	}

View on GitHub (pinned to e9452d6e78)

Solutions

Add an absolute host path as source, e.g. source: /srv/app/config.
If the source uses ${VAR} substitution, set the variable in the deploying shell or .env file and confirm with 'docker compose config'.
If you actually wanted an anonymous or named volume, change type to volume.

Example fix

# before
volumes:
  - type: bind
    target: /app/config
# after
volumes:
  - type: bind
    source: /srv/app/config
    target: /app/config

When it happens

Trigger: 'docker stack deploy' with a service volume entry of type: bind whose source is missing, empty, or an unset variable like ${HOST_PATH} that substitutes to empty.

Common situations: Undefined environment variables in source paths (very common in CI where the .env file is absent); forgetting source: after switching an entry from type: volume; short-form '- /container/path' entries meant as anonymous volumes but written under type: bind in long form.

Related errors

AI-assisted analysis of docker/cli@e9452d6e78 (2026-08-01). Data as JSON: /data/errors/156c6136cbf05081.json. Report an issue: GitHub.