#https://github.com/aws-samples/startup-kit-templates/blob/master/templates/vpc.cfn.yml
#---
AWSTemplateFormatVersion: 2010-09-09

Description: VPC Aurora PostgreSQL

# This VPC stack should be created first before any other
# CloudFormation stacks, such as a bastion stack, database
# stack and application stack
Parameters:

  AvailabilityZone1:
    Description: The first availability zone in the region
    Type: AWS::EC2::AvailabilityZone::Name
    ConstraintDescription: Must be a valid availability zone

  AvailabilityZone2:
    Description: The second availability zone in the region
    Type: AWS::EC2::AvailabilityZone::Name
    ConstraintDescription: Must be a valid availability zone

  ELBIngressPort:
    Description: The ELB ingress port used by security groups
    Type: Number
    MinValue: 0
    MaxValue: 65535
    ConstraintDescription: TCP ports must be between 0 - 65535
    Default: 80

  AppIngressPort:
    Description: The application ingress port used by security groups
    Type: Number
    MinValue: 0
    MaxValue: 65535
    ConstraintDescription: TCP ports must be between 0 - 65535
    Default: 80

  SingleNatGateway:
    Description: Set to true to only install one NAT gateway
    Type: String
    ConstraintDescription: Value must be true or false
    Default: true
    AllowedValues:
      - true
      - false

Metadata:
  AWS::CloudFormation::Interface:
    ParameterGroups:
      - Label:
          default: Region Availability Zones
        Parameters:
          - AvailabilityZone1
          - AvailabilityZone2
      - Label:
          default: Ingress Ports
        Parameters:
          - ELBIngressPort
          - AppIngressPort
    ParameterLabels:
      AvailabilityZone1:
        default: Availability Zone 1
      AvailabilityZone2:
        default: Availability Zone 2
      ELBIngressPort:
        default: Load Balancer Port
      AppIngressPort:
        default: Application Port

Conditions:
  CreateSingleNatGateway: !Equals [ !Ref SingleNatGateway, true ]
  CreateMultipleNatGateways: !Not [ Condition: CreateSingleNatGateway ]

Mappings:

  # Maps CIDR blocks to VPC and various subnets
  CIDRMap:
    VPC:
      CIDR: 10.50.0.0/16
    Public1:
      CIDR: 10.50.0.0/24
    Public2:
      CIDR: 10.50.1.0/24
    Private1:
      CIDR: 10.50.64.0/19
    Private2:
      CIDR: 10.50.96.0/19

Resources:

  VPC:
    Type: AWS::EC2::VPC
    Properties:
      CidrBlock: !FindInMap [CIDRMap, VPC, CIDR]
      EnableDnsSupport: true
      EnableDnsHostnames: true
      Tags:
      - Key: Name
        Value: !Ref "AWS::StackName"

  VPCFLogGroup:
    Type: 'AWS::Logs::LogGroup'
    Properties:
      RetentionInDays: 7

  VPCFlowLogIAMRole:
    Type: 'AWS::IAM::Role'
    Properties:
      AssumeRolePolicyDocument:
        Version: '2012-10-17'
        Statement:
        - Effect: Allow
          Principal:
            Service: 'vpc-flow-logs.amazonaws.com'
          Action: 'sts:AssumeRole'
      Policies:
      - PolicyName: 'flowlogs-policy'
        PolicyDocument:
          Version: '2012-10-17'
          Statement:
          - Effect: Allow
            Action:
            - 'logs:CreateLogStream'
            - 'logs:PutLogEvents'
            - 'logs:DescribeLogGroups'
            - 'logs:DescribeLogStreams'
            Resource: !GetAtt 'VPCFLogGroup.Arn'

  VPCFlowLog:
    Type: AWS::EC2::FlowLog
    Properties:
      DeliverLogsPermissionArn: !GetAtt VPCFlowLogIAMRole.Arn
      LogGroupName: !Ref VPCFLogGroup
      ResourceId: !Ref VPC
      ResourceType: VPC
      TrafficType: ALL

  PublicSubnet1:
    Type: AWS::EC2::Subnet
    Properties:
      VpcId: !Ref VPC
      CidrBlock: !FindInMap [ CIDRMap, Public1, CIDR ]
      AvailabilityZone: !Ref AvailabilityZone1
      Tags:
      - Key: Name
        Value: !Sub "${AWS::StackName}-PublicSubnet1"

  PublicSubnet2:
    Type: AWS::EC2::Subnet
    Properties:
      VpcId: !Ref VPC
      CidrBlock: !FindInMap [ CIDRMap, Public2, CIDR ]
      AvailabilityZone: !Ref AvailabilityZone2
      Tags:
      - Key: Name
        Value: !Sub "${AWS::StackName}-PublicSubnet2"

  PrivateSubnet1:
    Type: AWS::EC2::Subnet
    Properties:
      VpcId: !Ref VPC
      CidrBlock: !FindInMap [ CIDRMap, Private1, CIDR ]
      AvailabilityZone: !Ref AvailabilityZone1
      Tags:
      - Key: Name
        Value: !Sub "${AWS::StackName}-PrivateSubnet1"

  PrivateSubnet2:
    Type: AWS::EC2::Subnet
    Properties:
      VpcId: !Ref VPC
      CidrBlock: !FindInMap [ CIDRMap, Private2, CIDR ]
      AvailabilityZone: !Ref AvailabilityZone2
      Tags:
      - Key: Name
        Value: !Sub "${AWS::StackName}-PrivateSubnet2"

  InternetGateway:
    Type: AWS::EC2::InternetGateway
    Properties:
      Tags:
        - Key: Name
          Value: !Sub "${AWS::StackName}-igw"

  VPCGatewayAttachment:
    Type: AWS::EC2::VPCGatewayAttachment
    Properties:
      VpcId: !Ref VPC
      InternetGatewayId: !Ref InternetGateway

  PublicRouteTable:
    Type: AWS::EC2::RouteTable
    Properties:
      VpcId: !Ref VPC
      Tags:
      - Key: Name
        Value: !Sub "${AWS::StackName}-public-igw"

  PublicRoute:
    Type: AWS::EC2::Route
    DependsOn: VPCGatewayAttachment
    Properties:
      RouteTableId: !Ref PublicRouteTable
      DestinationCidrBlock: 0.0.0.0/0
      GatewayId: !Ref InternetGateway

  PublicSubnetRouteTableAssociation1:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Properties:
      SubnetId: !Ref PublicSubnet1
      RouteTableId: !Ref PublicRouteTable

  PublicSubnetRouteTableAssociation2:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Properties:
      SubnetId: !Ref PublicSubnet2
      RouteTableId: !Ref PublicRouteTable

  PublicSubnetNetworkAclAssociation1:
    Type: AWS::EC2::SubnetNetworkAclAssociation
    Properties:
      SubnetId: !Ref PublicSubnet1
      NetworkAclId: !GetAtt VPC.DefaultNetworkAcl

  PublicSubnetNetworkAclAssociation2:
    Type: AWS::EC2::SubnetNetworkAclAssociation
    Properties:
      SubnetId: !Ref PublicSubnet2
      NetworkAclId: !GetAtt VPC.DefaultNetworkAcl

  ELBSecurityGroup:
    Type: AWS::EC2::SecurityGroup
    Properties:
      GroupDescription: Enable HTTP/HTTPs ingress
      VpcId: !Ref VPC
      SecurityGroupIngress:
      - CidrIp: 0.0.0.0/0
        IpProtocol: tcp
        ToPort: !Ref ELBIngressPort
        FromPort: !Ref ELBIngressPort
      Tags:
      - Key: Name
        Value: !Sub "${AWS::StackName}-ELBSecurityGroup"

  ELBSecurityGroupToAppEgress:
    Type: AWS::EC2::SecurityGroupEgress  # prevent security group circular references
    Properties:
      GroupId: !Ref ELBSecurityGroup
      IpProtocol: tcp
      ToPort: !Ref AppIngressPort
      FromPort: !Ref AppIngressPort
      DestinationSecurityGroupId: !Ref AppSecurityGroup

  AppSecurityGroup:
    Type: AWS::EC2::SecurityGroup
    Properties:
      GroupDescription: Enable access from ELB to app
      VpcId: !Ref VPC
      SecurityGroupIngress:
      - SourceSecurityGroupId: !Ref ELBSecurityGroup
        IpProtocol: tcp
        ToPort: !Ref AppIngressPort
        FromPort: !Ref AppIngressPort
      - SourceSecurityGroupId: !Ref BastionSecurityGroup
        IpProtocol: tcp
        ToPort: 22
        FromPort: 22
      Tags:
      - Key: Name
        Value: !Sub "${AWS::StackName}-AppSecurityGroup"

  AppSecurityGroupFromELBIngress:
    Type: AWS::EC2::SecurityGroupIngress  # prevent security group circular references
    Properties:
      GroupId: !Ref AppSecurityGroup
      IpProtocol: tcp
      ToPort: !Ref AppIngressPort
      FromPort: !Ref AppIngressPort
      SourceSecurityGroupId: !Ref ELBSecurityGroup

  AppSecurityGroupFromBastionIngress:
    Type: AWS::EC2::SecurityGroupIngress  # prevent security group circular references
    Properties:
      GroupId: !Ref AppSecurityGroup
      IpProtocol: tcp
      ToPort: 22
      FromPort: 22
      SourceSecurityGroupId: !Ref BastionSecurityGroup

  #Customize as necessary https://docs.aws.amazon.com/elasticloadbalancing/latest/network/target-group-register-targets.html#target-security-groups
  AppSecurityGroupFromVPCIngress:
    Type: AWS::EC2::SecurityGroupIngress
    Properties:
      Description: Ingress from internal clients
      GroupId: !Ref AppSecurityGroup
      CidrIp: 0.0.0.0/0
      FromPort: !Ref AppIngressPort
      ToPort: !Ref AppIngressPort
      IpProtocol: tcp 

  BastionSecurityGroup:
    Type: AWS::EC2::SecurityGroup
    Properties:
      GroupDescription: Enable access to the bastion host
      VpcId: !Ref VPC
      SecurityGroupEgress:
      - CidrIp: 0.0.0.0/0
        IpProtocol: tcp
        ToPort: 80
        FromPort: 80
      - CidrIp: 0.0.0.0/0
        IpProtocol: tcp
        ToPort: 443
        FromPort: 443
      - CidrIp: 0.0.0.0/0
        IpProtocol: udp
        ToPort: 123
        FromPort: 123
      Tags:
      - Key: Name
        Value: !Sub "${AWS::StackName}-BastionSecurityGroup"

  BastionSecurityGroupToAppEgress:
    Type: AWS::EC2::SecurityGroupEgress  # prevent security group circular references
    Properties:
      GroupId: !Ref BastionSecurityGroup
      IpProtocol: tcp
      ToPort: 22
      FromPort: 22
      DestinationSecurityGroupId: !Ref AppSecurityGroup

  BastionSecurityGroupToPostgreSqlDbEgress:
    Type: AWS::EC2::SecurityGroupEgress
    Properties:
      GroupId: !Ref BastionSecurityGroup
      IpProtocol: tcp
      ToPort: 5432
      FromPort: 5432
      DestinationSecurityGroupId: !Ref DbSecurityGroup

  BastionSecurityGroupToPostgreMySqlDbEgress:
    Type: AWS::EC2::SecurityGroupEgress
    Properties:
      GroupId: !Ref BastionSecurityGroup
      IpProtocol: tcp
      ToPort: 3306
      FromPort: 3306
      DestinationSecurityGroupId: !Ref DbSecurityGroup

  DbSecurityGroup:
    Type: AWS::EC2::SecurityGroup
    Properties:
      GroupDescription: Enable access to the RDS DB
      VpcId: !Ref VPC
      SecurityGroupEgress:
      - CidrIp: 0.0.0.0/0
        IpProtocol: tcp
        ToPort: 3306
        FromPort: 3306
      - CidrIp: 0.0.0.0/0
        IpProtocol: tcp
        ToPort: 5432
        FromPort: 5432
      Tags:
      - Key: Name
        Value: !Sub "${AWS::StackName}-DbSecurityGroup"

  DbSecurityGroupFromBastionPostgreSqlIngress:
    Type: AWS::EC2::SecurityGroupIngress
    Properties:
      GroupId: !Ref DbSecurityGroup
      IpProtocol: tcp
      ToPort: 5432
      FromPort: 5432
      SourceSecurityGroupId: !Ref BastionSecurityGroup

  DbSecurityGroupFromBastionMySqlIngress:
    Type: AWS::EC2::SecurityGroupIngress
    Properties:
      GroupId: !Ref DbSecurityGroup
      IpProtocol: tcp
      ToPort: 3306
      FromPort: 3306
      SourceSecurityGroupId: !Ref BastionSecurityGroup

  DbSecurityGroupFromAppPostgreSqlIngress:
    Type: AWS::EC2::SecurityGroupIngress
    Properties:
      GroupId: !Ref DbSecurityGroup
      IpProtocol: tcp
      ToPort: 5432
      FromPort: 5432
      SourceSecurityGroupId: !Ref AppSecurityGroup

  DbSecurityGroupFromAppMySqlIngress:
    Type: AWS::EC2::SecurityGroupIngress
    Properties:
      GroupId: !Ref DbSecurityGroup
      IpProtocol: tcp
      ToPort: 3306
      FromPort: 3306
      SourceSecurityGroupId: !Ref AppSecurityGroup

  # NAT-related resources
  #
  # NAT is used to allow instances in private subnets to communicate with AWS
  # services, and pull down code and updates.

  NatGateway1:
    DependsOn: VPCGatewayAttachment
    Type: AWS::EC2::NatGateway
    Properties:
      AllocationId: !GetAtt NatEIP1.AllocationId
      SubnetId: !Ref PublicSubnet1

  NatGateway2:
    DependsOn: VPCGatewayAttachment
    Condition: CreateMultipleNatGateways
    Type: AWS::EC2::NatGateway
    Properties:
      AllocationId: !GetAtt NatEIP2.AllocationId
      SubnetId: !Ref PublicSubnet2

  NatEIP1:
    DependsOn: VPCGatewayAttachment
    Type: AWS::EC2::EIP
    Properties:
      Domain: vpc

  NatEIP2:
    DependsOn: VPCGatewayAttachment
    Condition: CreateMultipleNatGateways
    Type: AWS::EC2::EIP
    Properties:
      Domain: vpc

  NatRouteTable1:
    Type: AWS::EC2::RouteTable
    Properties:
      VpcId: !Ref VPC
      Tags:
      - Key: Name
        Value: !Sub "${AWS::StackName}-private-nat-1"

  NatRouteTable2:
    Type: AWS::EC2::RouteTable
    Condition: CreateMultipleNatGateways
    Properties:
      VpcId: !Ref VPC
      Tags:
      - Key: Name
        Value: !Sub "${AWS::StackName}-private-nat-2"

  NatRoute1:
    Type: AWS::EC2::Route
    DependsOn: VPCGatewayAttachment
    Properties:
      RouteTableId: !Ref NatRouteTable1
      DestinationCidrBlock: 0.0.0.0/0
      NatGatewayId: !Ref NatGateway1

  NatRoute2:
    Type: AWS::EC2::Route
    DependsOn: VPCGatewayAttachment
    Condition: CreateMultipleNatGateways
    Properties:
      RouteTableId: !Ref NatRouteTable2
      DestinationCidrBlock: 0.0.0.0/0
      NatGatewayId: !Ref NatGateway2

  PrivateSubnetRouteTableAssociation1:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Properties:
      SubnetId: !Ref PrivateSubnet1
      RouteTableId: !Ref NatRouteTable1

  PrivateSubnetRouteTableAssociationSingleNatGateway:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Condition: CreateSingleNatGateway
    Properties:
      SubnetId: !Ref PrivateSubnet2
      RouteTableId: !Ref NatRouteTable1

  PrivateSubnetRouteTableAssociation2:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Condition: CreateMultipleNatGateways
    Properties:
      SubnetId: !Ref PrivateSubnet2
      RouteTableId: !Ref NatRouteTable2

Outputs:

  Name:
    Description: VPC Stack Name
    Value: !Ref AWS::StackName
    Export:
      Name: !Sub ${AWS::StackName}-Name

  VPCId:
    Description: VPC ID
    Value: !Ref VPC
    Export:
      Name: !Sub "${AWS::StackName}-VpcID"

  VpcCidr:
    Description: Vpc cidr block
    Value: !FindInMap [ CIDRMap, VPC, CIDR ]
    Export:
      Name: !Sub "${AWS::StackName}-vpc-cidr"

  PublicSubnet1:
    Description: Public subnet 1 ID
    Value: !Ref PublicSubnet1
    Export:
      Name: !Sub "${AWS::StackName}-PublicSubnet1ID"

  PublicSubnet2:
    Description: Public subnet 2 ID
    Value: !Ref PublicSubnet2
    Export:
      Name: !Sub "${AWS::StackName}-PublicSubnet2ID"

  PrivateSubnet1:
    Description: Private subnet 1 ID
    Value: !Ref PrivateSubnet1
    Export:
      Name: !Sub "${AWS::StackName}-PrivateSubnet1ID"

  PrivateSubnet2:
    Description: Private subnet 2 ID
    Value: !Ref PrivateSubnet2
    Export:
      Name: !Sub "${AWS::StackName}-PrivateSubnet2ID"

  ELBSecurityGroup:
    Description: Security group ID for Internet-facing ELB
    Value: !GetAtt ELBSecurityGroup.GroupId
    Export:
      Name: !Sub "${AWS::StackName}-ELBSecurityGroupID"

  AppSecurityGroup:
    Description: Security group ID for app behind ELB
    Value: !GetAtt AppSecurityGroup.GroupId
    Export:
      Name: !Sub "${AWS::StackName}-AppSecurityGroupID"

  BastionSecurityGroup:
    Description: Security group ID for bastion host
    Value: !GetAtt BastionSecurityGroup.GroupId
    Export:
      Name: !Sub "${AWS::StackName}-BastionGroupID"

  DatabaseSecurityGroup:
    Description: Security group ID for RDS database
    Value: !GetAtt DbSecurityGroup.GroupId
    Export:
      Name: !Sub "${AWS::StackName}-DatabaseGroupID"

  ELBIngressPort:
    Description: ELB ingress port
    Value: !Ref ELBIngressPort
    Export:
      Name: !Sub "${AWS::StackName}-ELBIngressPort"

  AppIngressPort:
    Description: App ingress port
    Value: !Ref AppIngressPort
    Export:
      Name: !Sub "${AWS::StackName}-AppIngressPort"

  StackName: 
    Value: !Ref AWS::StackName
    Export:
      Name: !Sub "${AWS::StackName}-Stackname"