docker/cli · error

is not an absolute path

Error message

%s is not an absolute path

What it means

Thrown by validateLinuxPath when the resolved container path is not absolute (path.IsAbs returns false). The container-side path must start with '/'.

Solutions

1. Prefix the container path with '/', e.g. /dev/sda1:/mnt/data
2. Use an absolute path for the container destination

Example fix

# before
docker run --device /dev/sda1:data ...
# after
docker run --device /dev/sda1:/data ...

func validAbsContainerPath(spec string) error {
    parts := strings.SplitN(spec, ":", 3)
    containerPath := parts[len(parts)-1]
    if len(parts) == 3 {
        containerPath = parts[1]
    }
    if !filepath.IsAbs(containerPath) {
        return fmt.Errorf("container path %q must be absolute", containerPath)
    }
    return nil
}

When it happens

Trigger: Passing a relative path as the container destination, e.g. `--device /dev/sda1:relative/path` or `--mount` style with non-absolute container path. The check runs after path.Clean on the container path.

Common situations: Assuming the path is relative to the container's workdir; forgetting the leading slash; script interpolation that strips it.

Related errors

• bad format for path
• got a device
• unknown server OS
• invalid device specification
• invalid device cgroup format

AI-assisted analysis of docker/cli@4f84911bfe (2026-08-07). Data as JSON: /api/errors/19e0c96e535bcfab. Report an issue: GitHub.

Appendix: source

Thrown at cli/command/container/opts.go:1128

		if isValid := validator(split[1]); isValid {
			containerPath = split[0]
			mode = split[1]
			val = fmt.Sprintf("%s:%s", path.Clean(containerPath), mode)
		} else {
			containerPath = split[1]
			val = fmt.Sprintf("%s:%s", split[0], path.Clean(containerPath))
		}
	case 3:
		containerPath = split[1]
		mode = split[2]
		if isValid := validator(split[2]); !isValid {
			return val, fmt.Errorf("bad mode specified: %s", mode)
		}
		val = fmt.Sprintf("%s:%s:%s", split[0], containerPath, mode)
	}

	if !path.IsAbs(containerPath) {
		return val, fmt.Errorf("%s is not an absolute path", containerPath)
	}
	return val, nil
}

// validateAttach validates that the specified string is a valid attach option.
func validateAttach(val string) (string, error) {
	s := strings.ToLower(val)
	if slices.Contains([]string{"stdin", "stdout", "stderr"}, s) {
		return s, nil
	}
	return val, errors.New("valid streams are STDIN, STDOUT and STDERR")
}

func toNetipAddrSlice(ips []string) []netip.Addr {
	if len(ips) == 0 {
		return nil
	}
	netIPs := make([]netip.Addr, 0, len(ips))

View on GitHub (pinned to 4f84911bfe)