nested-stacks.template.json

{
  "AWSTemplateFormatVersion": "2010-09-09",
  "Description": "Nested Stacks",
  "Parameters": {
    "KeyName": {
      "Description": "Existing KeyPair",
      "Type": "AWS::EC2::KeyPair::KeyName",
      "ConstraintDescription": "Must be an existing key pair"
    },
    "VPCCIDR": {
      "Description": "VPC CIDR",
      "Type": "String",
      "Default": "10.0.0.0/16",
    },
    "SubnetCIDR": {
      "Description": "Subnet CIDR",
      "Type": "String",
      "Default": "10.0.2.0/24",
    }
  },
  "Resources": {
    "VPCStack": {
      "Type": "AWS::CloudFormation::Stack",
      "Properties": {
        "TemplateURL": "https://s3.amazonaws.com/.../VPC.template.json",
        "Parameters": {
          "KeyPairName": {
            "Ref": "KeyName"
          },
          "VPCCIDR": {
            "Ref": "VPCCIDR"
          },
          "SubnetCIDR": {
            "Ref": "SubnetCIDR"
          }
        }
      }
    },
    "DatabaseStack": {
      "Type": "AWS::CloudFormation::Stack",
      "Properties": {
        "TemplateURL": "https://s3.amazonaws.com/.../Database.template.json",
        "Parameters": {
          "KeyPairName": {
            "Ref": "KeyName"
          },
          "SubnetId": {
            "Fn::GetAtt": [
              "VPCStack",
              "Outputs.SubnetId"
            ]
          },
          "VPCId": {
            "Fn::GetAtt": [
              "VPCStack",
              "Outputs.VPCId"
            ]
          }
        }
      }
    }
  }
}