https://docs.aws.amazon.com/ja_jp/AWSCloudFormation/latest/UserGuide/gettingstarted.templatebasics.html

Outputs.json

"Outputs": {
  "InstallURL": {
    "Value": {
      "Fn::Join": [
        "",
        [
          "http://",
          {
            "Fn::GetAtt": [
              "ElasticLoadBalancer",
              "DNSName"
            ]
          },
          "/wp-admin/install.php"
        ]
      ]
    },
    "Description": "Installation URL of the WordPress website"
  },
  "WebsiteURL": {
    "Value": {
      "Fn::Join": [
        "",
        [
          "http://",
          {
            "Fn::GetAtt": [
              "ElasticLoadBalancer",
              "DNSName"
            ]
          }
        ]
      ]
    }
  }
}