CloudFormationのロールバック時に設定ファイルも元に戻す ref: http://qiita.com/ryo0301/items/c2141d05eda63b2d2bad

file0.txt

{
  "AWSTemplateFormatVersion": "2010-09-09",
  "Description": "CloudFormation rollback test",
  "Parameters": {
    "VersionId": {
      "Type": "String"
    }
  },
  "Resources": {
    "Group": {
      "Type": "AWS::AutoScaling::AutoScalingGroup",
      "CreationPolicy": {
        "ResourceSignal": {
          "Count": "2",
          "Timeout": "PT10M"
        }
      },
      "UpdatePolicy": {
        "AutoScalingRollingUpdate": {
          "MaxBatchSize": "1",
          "MinInstancesInService": "1",
          "WaitOnResourceSignals": "true",
          "PauseTime": "PT10M"
        },
        "AutoScalingScheduledAction": {
          "IgnoreUnmodifiedGroupSizeProperties": "true"
        }
      },
      "Properties": {
        "LaunchConfigurationName": { "Ref": "LaunchConfig" },
        "VPCZoneIdentifier": [
          "subnet-XXXXXXXX"
        ],
        "HealthCheckType": "EC2",
        "DesiredCapacity": "2",
        "MinSize": "2",
        "MaxSize": "2"
      }
    },
    "LaunchConfig": {
      "Type": "AWS::AutoScaling::LaunchConfiguration",
      "Properties": {
        "BlockDeviceMappings": [
          {
            "DeviceName": "/dev/xvda",
            "Ebs": {
              "VolumeType": "gp2",
              "VolumeSize": "8",
              "DeleteOnTermination": "true"
            }
          }
        ],
        "IamInstanceProfile": "test",
        "ImageId": "ami-383c1956",
        "InstanceType": "t2.micro",
        "InstanceMonitoring": "false",
        "UserData": {
          "Fn::Base64": {
            "Fn::Join": [
              "", [
                "#!/bin/bash\n",
                "yum update -y aws-cfn-bootstrap\n",
                "yum install -y nginx\n",
                "aws s3api get-object",
                " --bucket XXXXXXX",
                " --key nginx.conf",
                " --version-id '", {"Ref": "VersionId"}, "'",
                " /etc/nginx/nginx.conf\n",
                "service nginx start\n",
                "/opt/aws/bin/cfn-signal -e $?",
                " --stack ", {"Ref": "AWS::StackName"},
                " --resource Group",
                " --region ", {"Ref": "AWS::Region"}
              ]
            ]
          }
        }
      }
    }
  }
}

file1.txt

Received SUCCESS signal with UniqueId i-XXXXXXXX
Received SUCCESS signal with UniqueId i-XXXXXXXX

file2.txt

Received 1 FAILURE signal(s) out of 2. Unable to satisfy 100% MinSuccessfulInstancesPercent requirement

file3.txt

Received SUCCESS signal with UniqueId i-XXXXXXXX