nektos/act · error

%s is not an absolute path

Error message

%s is not an absolute path

What it means

The final check in validateLinuxPath requires the container-side path to be absolute (path.IsAbs). If it is relative, the original value is returned with '%s is not an absolute path' naming the container path.

Source

Thrown at pkg/container/docker_cli.go:1135

		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 4f41128141)

Solutions

1. Prefix the container path with '/', e.g. /dev/foo
2. Double-check the third segment is a valid rwm mode so segments are classified correctly
3. Remember the one-segment form maps the same path on both sides: --device /dev/foo

Example fix

# before
--device /dev/foo:dev/foo

# after
--device /dev/foo:/dev/foo

// Go: check container-side path is absolute before passing to act
parts := strings.SplitN(deviceVal, ":", 3)
containerPath := parts[len(parts)-1]
if len(parts) == 3 || (len(parts) == 2 && !isValidDeviceMode(parts[1])) {
    containerPath = parts[1]
}
if !path.IsAbs(containerPath) { return fmt.Errorf("container path %q must be absolute", containerPath) }

When it happens

Trigger: Passing a container path without a leading slash, e.g. --device /dev/foo:dev/foo, or a two-part value whose second segment is a relative path (which the mode validator rejects, causing it to be treated as the container path).

Common situations: Omitting the leading / when writing the in-container name; or intending a mode but typing something the validator rejects, so the parser misclassifies the segment as a path.

Related errors

• bad format for path: %s
• unknown server OS: %s
• invalid device specification: %s
• bad mode specified: %s
• --pid: invalid PID mode

AI-assisted analysis of nektos/act@4f41128141 (2026-08-15). Data as JSON: /api/errors/23e2e7a92b029501. Report an issue: GitHub.