hashicorp/nomad · error

invalid key/value pair %q: %w

Error message

invalid key/value pair %q: %w

What it means

KVBuilder.Add parses command-line '-var' style arguments into a key/value mapping. Each argument is delegated to add(); when add() fails, Add wraps the underlying error with the offending argument via %w so the bad input and root cause are both visible. It is a diagnostic wrapper, not a distinct failure mode.

Source

Thrown at command/var.go:184

// KVBuilder is a struct to build a key/value mapping based on a list
// of "k=v" pairs, where the value might come from stdin, a file, etc.
type KVBuilder struct {
	Stdin io.Reader

	result map[string]any
	stdin  bool
}

// Map returns the built map.
func (b *KVBuilder) Map() map[string]any {
	return b.result
}

// Add adds to the mapping with the given args.
func (b *KVBuilder) Add(args ...string) error {
	for _, a := range args {
		if err := b.add(a); err != nil {
			return fmt.Errorf("invalid key/value pair %q: %w", a, err)
		}
	}

	return nil
}

func (b *KVBuilder) add(raw string) error {
	// Regardless of validity, make sure we make our result
	if b.result == nil {
		b.result = make(map[string]any)
	}

	// Empty strings are fine, just ignored
	if raw == "" {
		return nil
	}

	// Split into key/value

View on GitHub (pinned to 482b49bf1a)

Solutions

1. Read the wrapped %w cause in the error message to see which sub-condition failed (stdin, format, or file read)
2. Fix the offending argument to be 'key=value' format, quoting it in the shell: -var 'key=value'
3. If programmatically building args, validate each entry contains exactly one '=' before calling Add

Example fix

// before
b.Add("mykey") // invalid key/value pair "mykey": format must be key=value
// after
b.Add("mykey=myvalue")

for _, a := range args {
	if a == "-" || a == "" || strings.Count(a, "=") != 1 {
		// handle: bare '-' needs Stdin set; otherwise require key=value
	}
}

err := b.Add(args...)
if err != nil {
	var wrapped *fmt.wrapError
	if errors.As(err, &wrapped) {
		log.Printf("bad var arg, cause: %v", errors.Unwrap(err))
	}
}

When it happens

Trigger: Calling KVBuilder.Add (directly or via parseArgsData) with any argument that add() rejects: bare '-' without a Stdin, '-' repeated, arguments that are not 'key=value' format, or values whose '@file' cannot be read.

Common situations: Users passing '-var foo' (no =) or '-var' with an empty value on the CLI; shell quoting splitting 'key=value' into two args; scripts feeding malformed vars into the builder.

Related errors

• format must be key=value
• Invalid key value pair for topic: %s
• stdin already consumed
• error reading file: %w
• not a terminal

AI-assisted analysis of hashicorp/nomad@482b49bf1a (2026-09-04). Data as JSON: /api/errors/cd81391c0e178923. Report an issue: GitHub.