hashicorp/nomad · error

generated unexpected hil type: %s

Error message

generated unexpected hil type: %s

What it means

InterpolateHIL evaluates a bind-name or token-name template with HIL and expects a string result. If HIL returns a non-string type (e.g. the template evaluates arithmetic/boolean expressions), this error is thrown.

Source

Thrown at lib/auth/binder.go:220

		vm[k] = ast.Variable{
			Type:  ast.TypeString,
			Value: v,
		}
	}

	config := &hil.EvalConfig{
		GlobalScope: &ast.BasicScope{
			VarMap: vm,
		},
	}

	result, err := hil.Eval(tree, config)
	if err != nil {
		return "", err
	}

	if result.Type != hil.TypeString {
		return "", fmt.Errorf("generated unexpected hil type: %s", result.Type)
	}

	return result.Value.(string), nil
}

View on GitHub (pinned to 482b49bf1a)

Solutions

1. Rewrite the template so the expression yields a string (wrap in quotes or literal text)
2. Use only string-typed claim variables in the template
3. Simplify the template to plain literals and ${claim} substitutions

Example fix

// before
BindName: "${1 + 1}"
// after
BindName: "team-${index}" // where index is a string claim mapping

// reject templates that are pure expressions without literal text
func isPlainStringTemplate(tmpl string) bool {
    return !regexp.MustCompile(`^\$\{[^}]*\}$`).MatchString(tmpl)
}

if err != nil && strings.Contains(err.Error(), "unexpected hil type") {
    return fmt.Errorf("bind template must evaluate to a string: %w", err)
}

When it happens

Trigger: A BindName or token name template whose HIL expression evaluates to a number or boolean, e.g. "${1 + 1}" or a variable inserted as a non-string ast.Variable by a caller.

Common situations: Copy-pasted HIL from Terraform using expressions instead of plain string interpolation; template with only a numeric expression and no surrounding text.

Related errors

• cannot compute %q bind name for bind target: %w
• no signed workload identity available
• JWT login returned an empty secret
• JWT login did not return a token
• ACL token expired

AI-assisted analysis of hashicorp/nomad@482b49bf1a (2026-09-04). Data as JSON: /api/errors/4a597d77616acb77. Report an issue: GitHub.