{
  "AWSTemplateFormatVersion": "2010-09-09",
  "Description": "A Subnet",
  "Conditions": {
    "tfIsTrueCondition": {
      "Fn::Equals": [
        {
          "Ref": "tf"
        },
        "true"
      ]
    },
    "tfIsFalseCondition": {
      "Fn::Equals": [
        {
          "Ref": "tf"
        },
        "false"
      ]
    },
    "condNonDefaultRouteTable": {
      "Fn::Not": [
        {
          "Fn::Equals": [
            {
              "Ref": "RouteTableId"
            },
            "default"
          ]
        }
      ]
    },
    "condNonDefaultAZ": {
      "Fn::Not": [
        {
          "Fn::Equals": [
            {
              "Ref": "AvailabilityZone"
            },
            "random"
          ]
        }
      ]
    },
    "condDefaultAZ": {
      "Fn::Equals": [
        {
          "Ref": "AvailabilityZone"
        },
        "random"
      ]
    }
  },
  "Outputs": {
    "SubnetId": {
      "Value": {
        "Ref": "Subnet"
      }
    },
    "AvailabilityZone": {
      "Value": {
        "Fn::GetAtt": [
          "Subnet",
          "AvailabilityZone"
        ]
      }
    }
  },
  "Parameters": {
    "SubnetCidr": {
      "Type": "String",
      "Default": "10.1.0.0/16",
      "AllowedPattern": "(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})/(\\d{1,2})",
      "MaxLength": "18",
      "MinLength": "9",
      "Description": "Subnet CIDR [x.x.x.x/x]",
      "ConstraintDescription": "must be a valid CIDR range formatted as x.x.x.x/x"
    },
    "AvailabilityZone": {
      "Default": "random",
      "Description": "Availability Zone",
      "Type": "String",
      "ConstraintDescription": "Must be a valid AZ for the region."
    },
    "VpcId": {
      "Description": "ID of an existing VPC to create the subnet in",
      "Type": "AWS::EC2::VPC::Id"
    },
    "RouteTableId": {
      "Description": "Route table that the subnet will attach to.",
      "Default": "default",
      "Type": "String",
      "MinLength": "1",
      "MaxLength": "255",
      "AllowedPattern": "[\\x20-\\x7E]*",
      "ConstraintDescription": "can contain only ASCII characters."
    },
    "NameTag": {
      "Description": "Set the name tag for all created resources.",
      "Default": "default",
      "Type": "String",
      "MinLength": "1",
      "MaxLength": "255",
      "AllowedPattern": "[\\x20-\\x7E]*",
      "ConstraintDescription": "can contain only ASCII characters."
    },
    "tf": {
      "Type": "String",
      "MaxLength": "5",
      "MinLength": "4",
      "ConstraintDescription": "[true|false]"
    }
  },
  "Resources": {
    "Subnet": {
      "Type": "AWS::EC2::Subnet",
      "Properties": {
        "CidrBlock": {
          "Ref": "SubnetCidr"
        },
        "AvailabilityZone": {
          "Fn::If": [
            "condNonDefaultAZ",
            {
              "Ref": "AvailabilityZone"
            },
            {
              "Ref": "AWS::NoValue"
            }
          ]
        },
        "VpcId": {
          "Ref": "VpcId"
        },
        "Tags": [
          {
            "Key": "Name",
            "Value": {
              "Ref": "NameTag"
            }
          }
        ]
      }
    },
    "RouteTableAssociation": {
      "Type": "AWS::EC2::SubnetRouteTableAssociation",
      "Condition": "condNonDefaultRouteTable",
      "Properties": {
        "RouteTableId": {
          "Ref": "RouteTableId"
        },
        "SubnetId": {
          "Ref": "Subnet"
        }
      }
    }
  }
}