title: Terraform Combine Variable and String
body: <p>I'm trying to do a rather simple task in Terraform and it's not working:</p>
  
  <p>tfvars:</p>
  
  <pre><code>hosted_zone       = "example.com"
  domain            = "my.${var.hosted_zone}"
  </code></pre>
  
  <p>route_53_record:</p>
  
  <pre><code>resource "aws_route53_record" "regional" {
    zone_id = "${data.aws_route53_zone.selected.zone_id}"
    name    = "${var.domain}"
    type    = "A"
    ttl     = "300"
    records = ["4.4.4.4"]
  }
  </code></pre>
  
  <p>When I run <code>terraform plan</code> I'm getting this:</p>
  
  <pre><code>+ aws_route53_record.regional
        id:                 &lt;computed&gt;
        allow_overwrite:    "true"
        fqdn:               &lt;computed&gt;
        name:               "my.${var.hosted_zone}"
        records.#:          "1"
        records.3178571330: "4.4.4.4"
        ttl:                "300"
        type:               "A"
        zone_id:            "REDACTED"
  </code></pre>
  
  <p>domain should be <code>my.example.com</code>. How do I join the variable hosted_zoned and a string to form domain? </p>