aws-refarch-wordpress-03-elasticache.yaml

---
AWSTemplateFormatVersion: 2010-09-09

Description: Reference Architecture to host WordPress on AWS - Creates ElastiCache cache cluster

Metadata:

  Authors:
    Description:  Darryl Osborne (darrylo@amazon.com), David McGovern (gov@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: Cache Parameters
      Parameters:
        - ElastiCacheNodeType
        - ElastiCacheSecurityGroup
        - NumberOfSubnets
        - Subnet
    ParameterLabels:
      ElastiCacheNodeType:
        default: Cache Cluster Node Type
      ElastiCacheSecurityGroup:
        default: ElastiCache Security Group
      NumberOfSubnets:
        default: Number of subnets
      Subnet:
        default: Subnets

Parameters:

  ElastiCacheNodeType:
    AllowedValues:
      - cache.t3.micro
      - cache.t3.small
      - cache.t3.medium
      - cache.m3.medium
      - cache.m5.large
      - cache.m5.xlarge
      - cache.m5.2xlarge
      - cache.m5.4xlarge
      - cache.m5.10xlarge
    ConstraintDescription: Must be a valid Amazon ElastiCache node type.
    Default: cache.t3.medium
    Description: The Amazon ElastiCache cluster node type.
    Type: String
  ElastiCacheSecurityGroup:
    Description: Select the ElastiCache security group.
    Type: AWS::EC2::SecurityGroup::Id
  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
  Subnet3: !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

Resources:

  ElastiCacheCluster:
    Type: AWS::ElastiCache::CacheCluster
    Properties:
      AZMode: cross-az
      CacheNodeType: !Ref ElastiCacheNodeType
      CacheSubnetGroupName: !Ref ElastiCacheSubnetGroup
      Engine: memcached
      NumCacheNodes:
        !Ref NumberOfSubnets
      Tags:
        - Key: Name
          Value: !Join [ '', [ 'WordPress / ', !Ref 'AWS::StackName' ] ]
      VpcSecurityGroupIds:
      - !Ref ElastiCacheSecurityGroup       
  ElastiCacheSubnetGroup: 
    Type: AWS::ElastiCache::SubnetGroup
    Properties: 
      Description: ElastiCache Subnet Group for WordPress
      SubnetIds: 
        !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 ] ]
                  ]
                ]
              ]
            ]
          ]
Outputs:
  ElastiCacheClusterEndpointAddress:
    Value: !GetAtt ElastiCacheCluster.ConfigurationEndpoint.Address