# CloudFormation Workshop - Template 1
#
# Parameters:
#
# (1) An Availability Zone using the built in pseudo parameter.
#
# Resources built:
#
# (1) An Amazon VPC
# (2) A public subnet
# (3) An Internet gateway
# (4) A route table
# (5) A default route
#
# Output values:
#
# VpcId - The ID of the VPC (e.g. vpc-123456789012345)
# SubnetId - The ID of the subnet (e.g. subnet-123456789012345)
# AzId - The Availability Zone of the subnet (e.g. us-east-1a)
---
AWSTemplateFormatVersion: '2010-09-09'

Description: Create a VPC

# Note the use of the AWS-specific parameter type.
#
# See:
#
# https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/parameters-section-structure.html

Parameters:
  AzName:
    Type: AWS::EC2::AvailabilityZone::Name
    Description: Subnet Availability Zone

Resources:
  Vpc:
    Type: AWS::EC2::VPC
    Properties:
      CidrBlock: 10.200.0.0/16
      EnableDnsHostnames: 'true'

  PublicSubnet:
    Type: AWS::EC2::Subnet
    Properties:
      AvailabilityZone: !Ref AzName
      CidrBlock: 10.200.11.0/24
      MapPublicIpOnLaunch: 'true'
      VpcId: !Ref Vpc

  VpcIgw:
    Type: AWS::EC2::InternetGateway

  VpcIgwAttachment:
    Type: AWS::EC2::VPCGatewayAttachment
    Properties:
      InternetGatewayId: !Ref VpcIgw
      VpcId: !Ref Vpc

# Note the use of the DependsOn attribute.  You need to use this to delay
# the creation of the route table if it contains a route that reports to
# an Internet Gateway.
#
# See:
#
# https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-attribute-dependson.html

  RouteTable:
    Type: AWS::EC2::RouteTable
    DependsOn: VpcIgwAttachment
    Properties:
      VpcId: !Ref Vpc

  DefaultRoute:
    Type: AWS::EC2::Route
    Properties:
      DestinationCidrBlock: 0.0.0.0/0
      GatewayId: !Ref VpcIgw
      RouteTableId: !Ref RouteTable

  AssociatePublicSubnetToRouteTable:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Properties:
      RouteTableId: !Ref RouteTable
      SubnetId: !Ref PublicSubnet

# Note that the output values are derived from the PublicSubnet resource.
# You can see what values !Ref and !GetAtt return by looking at the
# CloudFormation documentation for AWS::EC2::Subnet at:
#
# https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-ec2-subnet.html
#
# Note that we could have used !Ref AzName for the output value of AzId.
# The reason for not doing this will become apparent.

Outputs:

  SubnetId:
    Description: Subnet Id
    Value: !Ref PublicSubnet

  VpcId:
    Description: Vpc Id
    Value: !GetAtt PublicSubnet.VpcId

  AzName:
    Description: Subnet Availability Zone
    Value: !GetAtt PublicSubnet.AvailabilityZone
    
  VpcCidr:
    Description: Vpc Cidr Block
    Value: !GetAtt Vpc.CidrBlock