Amazon CloudFormation Template (AutoScaling)

Amazon CloudFormation Template (AutoScaling)

{
  "Description" : "ProjectX scalable stack of frontal nodes",
  "Parameters" : {
    "InstanceType" : {
      "Description" : "Type of EC2 instance to launch",
      "Type" : "String",
      "Default" : "m1.xlarge"
    },
    "SSHKeyName" : {
      "Description" : "The EC2 Key Pair to allow SSH access to the instances",
      "Type" : "String",
      "Default" : "projectx"
    },
    "ChefAPIUrl" : {
      "Description" : "Chef API Url",
      "Type" : "String",
      "Default" : "http://my-chefapi.com"
    },
    "FrontNodePEM" : {
      "Description" : "Frontal node client.pem contents with double escaped new lines like \\\\n",
      "Type" : "String",
      "Default" : "-----BEGIN RSA PRIVATE KEY-----\\nMI...=\\n-----END RSA PRIVATE KEY-----"
    },
    "FrontNodeName" : {
      "Description" : "Frontal node name in chef (node should be already created)",
      "Type" : "String",
      "Default" : "projectx-live-node"
    },
    "AWSRegion" : {
      "Type" : "String",
      "Default" : "eu-west-1"
    },
    "InstanceName" : {
      "Description" : "Logical instance name seen in AWS console",
      "Type" : "String",
      "Default" : "ProjectX-Live-Node"
    },
    "AvailabilityZones" : {
      "Type" : "CommaDelimitedList",
      "Default" : "eu-west-1a"
    }
  },

"Mappings" : {
    "AWSInstanceType2Arch" : {
      "t1.micro"    : { "Arch" : "64" },
      "m1.small"    : { "Arch" : "32" },
      "m1.large"    : { "Arch" : "64" },
      "m1.xlarge"   : { "Arch" : "64" },
      "m2.xlarge"   : { "Arch" : "64" },
      "m2.2xlarge"  : { "Arch" : "64" },
      "m2.4xlarge"  : { "Arch" : "64" },
      "c1.medium"   : { "Arch" : "32" },
      "c1.xlarge"   : { "Arch" : "64" },
      "cc1.4xlarge" : { "Arch" : "64" }
    },
    "AWSRegionArch2AMI" : {
      "us-east-1" : { "32" : "ami-b89842d1", "64" : "ami-3c994355" },
      "us-west-1" : { "32" : "ami-d5712a90", "64" : "ami-e7712aa2" },
      "eu-west-1" : { "32" : "ami-25e8d351", "64" : "ami-3b65664f" }
    }
  },

  "Resources" : {
    "NodeGroup" : {
      "Type" : "AWS::AutoScaling::AutoScalingGroup",
      "Properties" : {
        "AvailabilityZones" : {"Ref": "AvailabilityZones"},
        "LaunchConfigurationName" : { "Ref" : "LaunchConfig" },
        "MinSize" : "1",
        "MaxSize" : "2",
        "LoadBalancerNames" : [ { "Ref" : "ElasticLoadBalancer" } ],
        "Tags" : [
                {"Key" : "Client", "Value" : "ProjectX", "PropagateAtLaunch" : "true"}, 
                {"Key" : "Type", "Value" : "Prod", "PropagateAtLaunch" : "true"},
                {"Key" : "Use", "Value" : "Web", "PropagateAtLaunch" : "true"},
                {"Key" : "Name", "Value" : {"Ref" : "InstanceName"}, "PropagateAtLaunch" : "true"}
        ] 
      }
   },

    "LaunchConfig" : {
      "Type" : "AWS::AutoScaling::LaunchConfiguration",
      "Properties" : {
        "ImageId" : { "Fn::FindInMap" : [ "AWSRegionArch2AMI", { "Ref" : "AWS::Region" },
                                          { "Fn::FindInMap" : [ "AWSInstanceType2Arch", { "Ref" : "InstanceType" },
                                          "Arch" ] } ] },
        "UserData" : { "Fn::Base64" : { "Fn::Join":
                                                [ "", [
                                                    "#!/bin/bash\n",
                                                    "echo \"deb http://apt.opscode.com/ `lsb_release -cs`-0.10 main\" | sudo tee /etc/apt/sources.list.d/opscode.list\n",
                                                    "sudo mkdir -p /etc/apt/trusted.gpg.d\n",
                                                    "gpg --keyserver keys.gnupg.net --recv-keys 83EF826A\n",
                                                    "gpg --export packages@opscode.com | sudo tee /etc/apt/trusted.gpg.d/opscode-keyring.gpg > /dev/null\n",
                                                    "apt-get -y update\n",
                                                    "apt-get -y install opscode-keyring\n",
                                                    "export DEBIAN_FRONTEND=noninteractive\n",
                                                    "apt-get -y upgrade\n",
                                                    "echo 'chef chef/chef_server_url string ",
                                                    {"Ref" : "ChefAPIUrl"},
                                                    "' |  debconf-set-selections\n",
                                                    "apt-get -y install chef\n",
                                                    "echo -e \"", {"Ref": "FrontNodePEM"},"\" > /etc/chef/client.pem\n",
                                                    "echo 'node_name \t\"", {"Ref": "FrontNodeName"}, "\"' >> /etc/chef/client.rb\n",
                                                    "sudo dd if=/dev/zero of=/mnt/swap bs=1M count=8096\n",
                                                    "sudo chmod 600 /mnt/swap\n",
                                                    "sudo mkswap /mnt/swap\n",
                                                    "sudo swapon /mnt/swap\n",
                                                    "/usr/bin/chef-client"
                                                ]]
                                            }
                            },
        "SecurityGroups" : [{ "Ref" : "ProjectXNodeSecurityGroup" }],
        "InstanceType" : {"Ref" : "InstanceType"},
        "KeyName" : {"Ref": "SSHKeyName"}
      }
    },

    "WebServerScaleUpPolicy" : {
      "Type" : "AWS::AutoScaling::ScalingPolicy",
      "Properties" : {
        "AdjustmentType" : "PercentChangeInCapacity",
        "AutoScalingGroupName" : { "Ref" : "NodeGroup" },
        "Cooldown" : "300",
        "ScalingAdjustment" : "100"
      }
    },
    "WebServerScaleDownPolicy" : {
      "Type" : "AWS::AutoScaling::ScalingPolicy",
      "Properties" : {
        "AdjustmentType" : "ChangeInCapacity",
        "AutoScalingGroupName" : { "Ref" : "NodeGroup" },
        "Cooldown" : "600",
        "ScalingAdjustment" : "-1"
      }
    },

    "CPUAlarmHigh": {
     "Type": "AWS::CloudWatch::Alarm",
     "Properties": {
        "AlarmDescription": "Scale-up if CPU > 40% for 10 minutes",
        "MetricName": "CPUUtilization",
        "Namespace": "AWS/EC2",
        "Statistic": "Average",
        "Period": "120",
        "EvaluationPeriods": "5",
        "Threshold": "40",
        "AlarmActions": [ { "Ref": "WebServerScaleUpPolicy" } ],
        "Dimensions": [
          {
            "Name": "AutoScalingGroupName",
            "Value": { "Ref": "NodeGroup" }
          }
        ],
        "ComparisonOperator": "GreaterThanThreshold"
      }
    },
    "CPUAlarmLow": {
     "Type": "AWS::CloudWatch::Alarm",
     "Properties": {
        "AlarmDescription": "Scale-down if CPU <20% for 60 min",
        "MetricName": "CPUUtilization",
        "Namespace": "AWS/EC2",
        "Statistic": "Average",
        "Period": "120",
        "EvaluationPeriods": "30",
        "Threshold": "20",
        "AlarmActions": [ { "Ref": "WebServerScaleDownPolicy" } ],
        "Dimensions": [
          {
            "Name": "AutoScalingGroupName",
            "Value": { "Ref": "NodeGroup" }
          }
        ],
        "ComparisonOperator": "LessThanThreshold"
      }
    },

    "ElasticLoadBalancer" : {
      "Type" : "AWS::ElasticLoadBalancing::LoadBalancer",
      "Properties" : {
        "AvailabilityZones" : {"Ref": "AvailabilityZones"},
        "Listeners" : [ {
          "LoadBalancerPort" : "80",
          "InstancePort" : "80",
          "Protocol" : "HTTP"
        } ],
        "HealthCheck" : {
          "Target" : { "Fn::Join" : [ "", ["HTTP:", "80", "/healthchecker.php"]]},
          "HealthyThreshold" : "10",
          "UnhealthyThreshold" : "5",
          "Interval" : "20",
          "Timeout" : "10"
        }
      }
    },

    "ProjectXNodeSecurityGroup" : {
      "Type" : "AWS::EC2::SecurityGroup",
      "Properties" : {
        "GroupDescription" : "Enable SSH access and HTTP access on the inbound port",
        "SecurityGroupIngress" : 
          [ { "IpProtocol" : "tcp", "FromPort" : "22", "ToPort" : "22", "CidrIp" : "0.0.0.0/0" },
            { "IpProtocol" : "tcp", "FromPort" : "80", "ToPort" : "80", "CidrIp" : "0.0.0.0/0" }
          ]
      }
    }
  },

  "Outputs" : {
    "URL" : {
      "Description" : "The URL of the website",
      "Value" :  { "Fn::Join" : [ "", [ "http://", { "Fn::GetAtt" : [ "ElasticLoadBalancer", "DNSName" ]}]]}
    }
  }
}