docker/cli · error

variable '%s' contains whitespaces

Error message

variable '%s' contains whitespaces

What it means

Error "variable '%s' contains whitespaces" thrown in docker/cli.

Source

Thrown at pkg/kvfile/kvfile.go:112

		// trim the line from all leading whitespace first. trailing whitespace
		// is part of the value, and is kept unmodified.
		line := strings.TrimLeftFunc(string(scannedBytes), unicode.IsSpace)

		if len(line) == 0 || line[0] == '#' {
			// skip empty lines and comments (lines starting with '#')
			continue
		}

		key, _, hasValue := strings.Cut(line, "=")
		if len(key) == 0 {
			return []string{}, fmt.Errorf("no variable name on line '%s'", line)
		}

		// leading whitespace was already removed from the line, but
		// variables are not allowed to contain whitespace or have
		// trailing whitespace.
		if strings.ContainsAny(key, whiteSpaces) {
			return []string{}, fmt.Errorf("variable '%s' contains whitespaces", key)
		}

		if hasValue {
			// key/value pair is valid and has a value; add the line as-is.
			lines = append(lines, line)
			continue
		}

		if lookupFn != nil {
			// No value given; try to look up the value. The value may be
			// empty but if no value is found, the key is omitted.
			if value, found := lookupFn(line); found {
				lines = append(lines, key+"="+value)
			}
		}
	}
	return lines, scanner.Err()
}

View on GitHub (pinned to e9452d6e78)

When it happens

Trigger: Thrown at pkg/kvfile/kvfile.go:112 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of docker/cli@e9452d6e78 (2026-08-01). Data as JSON: /data/errors/a94e563e3f7e1be6.json. Report an issue: GitHub.