---
AWSTemplateFormatVersion: 2010-09-09

Description: Reference Architecture to host WordPress on AWS - Creates bastion (desired:0; min:0; max:1) Auto Scaling group

Metadata:

  Authors:
    Description: Darryl Osborne (darrylo@amazon.com)
  License:
    Description: 'Copyright 2018 Amazon.com, Inc. and its affiliates. All Rights Reserved.
                  SPDX-License-Identifier: MIT-0'

  AWS::CloudFormation::Interface:
    ParameterGroups:
    - Label:
        default: AWS Parameters
      Parameters:
        - EC2KeyName
        - BastionInstanceType
        - BastionSecurityGroup
        - NumberOfSubnets
        - Subnet
    ParameterLabels:
      BastionSecurityGroup:
        default: Bastion Security Group
      BastionInstanceType:
        default: Instance Type
      EC2KeyName:
        default: Existing Key Pair
      NumberOfSubnets:
        default: Number of subnets
      Subnet:
        default: Subnets

Parameters:

  BastionSecurityGroup:
    Description: Select the bastion security group.
    Type: AWS::EC2::SecurityGroup::Id
  BastionInstanceType:
    AllowedValues:
    - t3.medium
    - t3.micro
    - t3.nano
    - t3.small
    ConstraintDescription: Must be a valid Amazon EC2 instance type.
    Default: t3.nano
    Description: Bastion EC2 instance type.
    Type: String
  EC2KeyName:
    Description: Name of an EC2 KeyPair. Your bastion instances will launch with this KeyPair.
    Type: AWS::EC2::KeyPair::KeyName
  NumberOfSubnets:
    AllowedValues:
    - 2
    - 3
    - 4
    - 5
    - 6
    Default: 3
    Description: Number of subnets. This must match your selections in the list of subnets below.
    Type: String 
  Subnet:
    Description: Select existing subnets. The number selected must match the number of subnets above. Subnets selected must be in separate AZs.
    Type: List<AWS::EC2::Subnet::Id>

Conditions:

  NumberOfSubnets1:
      !Equals [ 1, !Ref NumberOfSubnets ]
  NumberOfSubnets2:
      !Equals [ 2, !Ref NumberOfSubnets ]
  NumberOfSubnets3:
      !Equals [ 3, !Ref NumberOfSubnets ]
  NumberOfSubnets4:
      !Equals [ 4, !Ref NumberOfSubnets ]
  NumberOfSubnets5:
      !Equals [ 5, !Ref NumberOfSubnets ]
  NumberOfSubnets6:
      !Equals [ 6, !Ref NumberOfSubnets ]
  Subnet0: !Or
    - !Condition NumberOfSubnets1
    - !Condition NumberOfSubnets2
    - !Condition NumberOfSubnets3
    - !Condition NumberOfSubnets4
    - !Condition NumberOfSubnets5
    - !Condition NumberOfSubnets6
  Subnet1: !Or
    - !Condition NumberOfSubnets2
    - !Condition NumberOfSubnets3
    - !Condition NumberOfSubnets4
    - !Condition NumberOfSubnets5
    - !Condition NumberOfSubnets6
  Subnet2: !Or
    - !Condition NumberOfSubnets3
    - !Condition NumberOfSubnets4
    - !Condition NumberOfSubnets5
    - !Condition NumberOfSubnets6
  Subnet3: !Or
    - !Condition NumberOfSubnets4
    - !Condition NumberOfSubnets5
    - !Condition NumberOfSubnets6
  Subnet4: !Or
    - !Condition NumberOfSubnets5
    - !Condition NumberOfSubnets6
  Subnet5: !Condition NumberOfSubnets6

Mappings:

  RegionMap:
    ap-northeast-1:
      AMI: ami-0de5311b2a443fb89
    ap-northeast-2:
      AMI: ami-09cf633fe86e51bf0
    ap-south-1:
      AMI: ami-0e6329e222e662a52
    ap-southeast-1:
      AMI: ami-094bbd9e922dc515d
    ap-southeast-2:
      AMI: ami-02a66f06b3557a897
    ca-central-1:
      AMI: ami-088d4832275406edf
    eu-central-1:
      AMI: ami-070b208e993b59cea
    eu-west-1:
      AMI: ami-0ee415e1b8b71305f
    eu-west-2:
      AMI: ami-0648ea225c13e0729
    sa-east-1:
      AMI: ami-0122c4b16734197ac
    us-east-1:
      AMI: ami-09d3b3274b6c5d4aa
    us-east-2:
      AMI: ami-089a545a9ed9893b6
    us-west-1:
      AMI: ami-017c001a88dd93847
    us-west-2:
      AMI: ami-0d593311db5abb72b

Resources:

  BastionAutoScalingGroup:
    Type: AWS::AutoScaling::AutoScalingGroup
    Properties:
      Cooldown: 60
      HealthCheckGracePeriod: 120
      HealthCheckType: EC2
      LaunchConfigurationName: !Ref BastionLaunchConfiguration
      MaxSize: 1
      MinSize: 0
      Tags:
        - Key: Name
          Value: !Join [ '', [ 'Bastion / ', !Ref 'AWS::StackName' ] ]
          PropagateAtLaunch: true
      VPCZoneIdentifier:
        !If
          [ NumberOfSubnets1,
          [ !Select [ 0, !Ref Subnet ] ],
          !If
            [ NumberOfSubnets2,
            [ !Select [ 0, !Ref Subnet ], !Select [ 1, !Ref Subnet ] ],
            !If
              [ NumberOfSubnets3,
              [ !Select [ 0, !Ref Subnet ], !Select [ 1, !Ref Subnet ], !Select [ 2, !Ref Subnet ] ],
              !If
                [ NumberOfSubnets4,
                [ !Select [ 0, !Ref Subnet ], !Select [ 1, !Ref Subnet ], !Select [ 2, !Ref Subnet ], !Select [ 3, !Ref Subnet ] ],
                !If
                  [ NumberOfSubnets5,
                  [ !Select [ 0, !Ref Subnet ], !Select [ 1, !Ref Subnet ], !Select [ 2, !Ref Subnet ], !Select [ 3, !Ref Subnet ], !Select [ 4, !Ref Subnet ] ],
                  [ !Select [ 0, !Ref Subnet ], !Select [ 1, !Ref Subnet ], !Select [ 2, !Ref Subnet ], !Select [ 3, !Ref Subnet ], !Select [ 4, !Ref Subnet ], !Select [ 5, !Ref Subnet ] ]
                  ]
                ]
              ]
            ]
          ]
  BastionLaunchConfiguration:
    Type: AWS::AutoScaling::LaunchConfiguration
    Properties:
      IamInstanceProfile: !Ref BastionInstanceProfile
      ImageId: !FindInMap [ RegionMap, !Ref 'AWS::Region', AMI ]
      InstanceMonitoring: true
      InstanceType: !Ref BastionInstanceType
      KeyName: !Ref EC2KeyName
      SecurityGroups:
        - !Ref BastionSecurityGroup
  BastionInstanceProfile:
    Type: AWS::IAM::InstanceProfile
    Properties:
      Path: '/'
      Roles:
      - !Ref BastionInstanceRole
  BastionInstanceRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Version: 2012-10-17
        Statement:
        - Effect: Allow
          Principal:
            Service:
            - ec2.amazonaws.com
          Action:
          - sts:AssumeRole
      Path: '/'
      Policies:
      - PolicyName: logs
        PolicyDocument:
          Version: 2012-10-17
          Statement:
          - Effect: Allow
            Action:
            - logs:CreateLogGroup
            - logs:CreateLogStream
            - logs:PutLogEvents
            - logs:DescribeLogStreams
            Resource:
            - arn:aws:logs:*:*:*