cfn-hup example

cfn-hup.yaml

AWSTemplateFormatVersion: '2010-09-09'
Description: AWS CloudFormation Sample Template for CFN Init
Parameters:
  KeyName:
    Description: Name of an existing EC2 KeyPair to enable SSH access to the instances
    Type: AWS::EC2::KeyPair::KeyName
    ConstraintDescription: must be the name of an existing EC2 KeyPair.
  
  LatestLinuxAmiId:
    Type: 'AWS::SSM::Parameter::Value<AWS::EC2::Image::Id>'
    Default: '/aws/service/ami-amazon-linux-latest/amzn2-ami-hvm-x86_64-gp2'

  WelcomeMessage:
    Type: String
    Default: "Hello World"
    
Resources:
  WebServerSecurityGroup:
    Type: AWS::EC2::SecurityGroup
    Properties:
      GroupDescription: Enable HTTP access via port 80 and SSH access via port 22
      SecurityGroupIngress:
      - IpProtocol: tcp
        FromPort: '80'
        ToPort: '80'
        CidrIp: 0.0.0.0/0
      - IpProtocol: tcp
        FromPort: '22'
        ToPort: '22'
        CidrIp: 0.0.0.0/0

  WebServerHost:
    Type: AWS::EC2::Instance
    Metadata:
      Comment: Install a simple PHP application
      AWS::CloudFormation::Init:
        config:
          packages:
            yum:
              httpd: []
              php: []
          groups:
            apache: {}
          users:
            "apache":
              groups:
                - "apache"
          sources:
            "/home/ec2-user/aws-cli": "https://github.com/aws/aws-cli/tarball/master"
          files:
            "/var/www/html/index.html":
              content: !Sub |
                <h1>${WelcomeMessage} from ${AWS::StackName}</h1>
              mode: '000644'
              owner: apache
              group: apache
            # The cfn-hup.conf file stores the name of the stack and the AWS credentials that the cfn-hup daemon targets.
            "/etc/cfn/cfn-hup.conf":
              content: !Sub |
                [main]
                stack=${AWS::StackId}
                region=${AWS::Region}
                # The interval used to check for changes to the resource metadata in minutes. Default is 15
                interval=2
              mode: "000400"
              owner: "root"
              group: "root"
            # The user actions that the cfn-hup daemon calls periodically are defined in the hooks.conf configuration file.
            # To support composition of several applications deploying change notification hooks, cfn-hup supports a directory named hooks.d that is located in the hooks configuration directory. You can place one or more additional hooks configuration files in the hooks.d directory. The additional hooks files must use the same layout as the hooks.conf file.
            "/etc/cfn/hooks.d/cfn-auto-reloader.conf":
              content: !Sub |
                [cfn-auto-reloader-hook]
                triggers=post.update
                path=Resources.WebServerHost.Metadata.AWS::CloudFormation::Init
                action=/opt/aws/bin/cfn-init -v --stack ${AWS::StackName} --resource WebServerHost --region ${AWS::Region}
              mode: "000400"
              owner: "root"
              group: "root"
          services:
            sysvinit:
              httpd:
                enabled: 'true'
                ensureRunning: 'true'
    CreationPolicy:
      ResourceSignal:
        Timeout: PT5M
    Properties:
      ImageId: !Ref LatestLinuxAmiId
      KeyName:
        Ref: KeyName
      InstanceType: t2.micro
      SecurityGroups:
      - Ref: WebServerSecurityGroup
      UserData:
        "Fn::Base64":
          !Sub |
            #!/bin/bash -xe
            # Get the latest CloudFormation package
            yum update -y aws-cfn-bootstrap
            # Start cfn-init
            /opt/aws/bin/cfn-init -s ${AWS::StackId} -r WebServerHost --region ${AWS::Region} || error_exit 'Failed to run cfn-init'
            # Start up the cfn-hup daemon to listen for changes to the EC2 instance metadata
            /opt/aws/bin/cfn-hup || error_exit 'Failed to start cfn-hup'
            # All done so signal success
            /opt/aws/bin/cfn-signal -e $? --stack ${AWS::StackId} --resource WebServerHost --region ${AWS::Region}

Outputs:
  InstanceId:
    Description: The instance ID of the web server
    Value:
      Ref: WebServerHost
  WebsiteURL:
    Value:
      !Sub 'http://${WebServerHost.PublicDnsName}'
    Description: URL for newly created LAMP stack
  PublicIP:
    Description: Public IP address of the web server
    Value:
      !GetAtt WebServerHost.PublicIp


# Get metadata (change the region accordingly)
# /opt/aws/bin/cfn-get-metadata --stack CfnHupDemo --resource WebServerHost --region eu-west-1