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    Resource Orchestration Service:Manage multiple ECS instances using a scaling group

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    Resource Orchestration Service:Manage multiple ECS instances using a scaling group

    Last Updated:Jun 18, 2026

    Learn how to edit a Resource Orchestration Service (ROS) template to manage multiple Elastic Compute Service (ECS) instances by using a scaling group, progressing from a simple configuration to a more complex one.

    Prerequisites

    Familiarize yourself with the template syntax and structure. For more information, see Quick Start.

    Sample scenario

    Create a scaling group with scaling rules in an Alibaba Cloud virtual private cloud (VPC), add ECS instances to the group, and then scale the instances out or in based on the configured rules.2023-03-29_10-36-10

    Usage notes

    View the property details for each resource type. For more information, see View resource types.

    Each resource type defines the type, requirements, and update policy for its properties. Required properties must be declared in the `Properties` section of the `Resources` block. Optional properties do not need to be declared. If a property allows updates, you can modify it in a new template and then update the stack to apply the changes. Otherwise, the property cannot be updated.

    Edit the template

    You can find the required resource types in the resource type index document. For more information, see Resource type index.

    This scenario requires you to create a VPC (ALIYUN::ECS::VPC), an ECS instance (ALIYUN::ECS::Instance), and a scaling group (ALIYUN::ESS::ScalingGroup). You also need a vSwitch (ALIYUN::ECS::VSwitch) and a security group (ALIYUN::ECS::SecurityGroup) for the ECS instance, a scaling configuration (ALIYUN::ESS::ScalingConfiguration) for the scaling group, and a resource to enable the scaling group (ALIYUN::ESS::ScalingGroupEnable).

    Define template resources and their dependencies

    Define basic network resources

    Define the basic network resources `Vpc`, `vSwitch`, and `EcsSecurityGroup` in the template.

    • Use the `Ref` intrinsic function and the `ALIYUN::StackName` pseudo parameter to retrieve the stack name and use it as the value for resource properties, such as `VpcName` in `Vpc` and `VSwitchName` in `vSwitch`. For more information, see Ref and ALIYUN::StackName.

    • Use the `Fn::Select` and `Fn::GetAZs` intrinsic functions with the `ALIYUN::Region` pseudo parameter to retrieve the ID of the first zone in the region where the stack is created, such as for the `ZoneId` property of `vSwitch`. For more information, see Functions and ALIYUN::Region.

    Resources:
  Vpc:
    Type: ALIYUN::ECS::VPC
    Properties:
      CidrBlock: 192.168.0.0/16
      VpcName:
        Ref: ALIYUN::StackName
  VSwitch:
    Type: ALIYUN::ECS::VSwitch
    Properties:
      VSwitchName:
        Ref: ALIYUN::StackName
      VpcId:
        Ref: Vpc
      ZoneId:
        Fn::Select:
          - '0'
          - Fn::GetAZs:
              Ref: ALIYUN::Region
      CidrBlock: 192.168.0.0/24
  EcsSecurityGroup:
    Type: ALIYUN::ECS::SecurityGroup
    Properties:
      SecurityGroupName:
        Ref: ALIYUN::StackName
      VpcId:
        Ref: Vpc
      SecurityGroupEgress:
        - PortRange: '-1/-1'
          Priority: 1
          IpProtocol: all
          DestCidrIp: 0.0.0.0/0
          NicType: intranet

    Define ECS resources

    Define the ECS resource `EcsInstanceGroup` in the template.

    Use the `Ref` intrinsic function to reference the logical names of other resources in the template, such as `VpcId` of the `Vpc` resource, `SecurityGroupId` of the `EcsSecurityGroup` resource, and `VSwitchId` of the `vSwitch` resource. For more information, see Ref.

    Resources:
	EcsInstanceGroup:
    Type: ALIYUN::ECS::Instance
    Properties:
      VpcId:
        Ref: Vpc
      SecurityGroupId:
        Ref: EcsSecurityGroup
      VSwitchId:
        Ref: VSwitch
      ImageId: centos_7
      AllocatePublicIP: false
      InstanceType: ecs.c5.large
      SystemDiskSize: 40
      SystemDiskCategory: cloud_essd
      Password:
        Ref: EcsInstancePassword

    Define scaling group resources

    Define the scaling group resources `EssInstanceScalingGroup`, `EssInstanceScalingGroupEnable`, and `EssInstanceScalingConfiguration` in the template.

    • Use the `Fn::GetAtt` intrinsic function to retrieve the value of a resource attribute, such as `InstanceIds` in `EssInstanceScalingGroupEnable`. For more information, see Fn::GetAtt.

    • Use the `Fn::Sub` intrinsic function to substitute variables in an input string with specified values. For example, you can use this function for the `ScalingConfigurationName` property in `EssInstanceScalingConfiguration`. For more information, see Fn::Sub.

    Resources:
	EssInstanceScalingGroup:
    Type: ALIYUN::ESS::ScalingGroup
    Properties:
      ScalingGroupName:
        Ref: ALIYUN::StackName
      RemovalPolicys:
        - NewestInstance
      MinSize: 3
      MaxSize: 50
      VSwitchId:
        Ref: VSwitch
      DefaultCooldown: 300
  EssInstanceScalingConfiguration:
    Type: ALIYUN::ESS::ScalingConfiguration
    Properties:
      SecurityGroupId:
        Ref: EcsSecurityGroup
      ScalingGroupId:
        Ref: EssInstanceScalingGroup
      ScalingConfigurationName:
        Fn::Sub: sc-${ALIYUN::StackName}
      InstanceType: ecs.c5.large
      SystemDiskCategory: cloud_essd
      SystemDiskSize: 200
      ImageId: centos_7_9_x64_20G_alibase_20220727.vhd
      InstanceName:
        Fn::Join:
          - '-'
          - - Ref: ALIYUN::StackName
            - '[1,4]'
  EssInstanceScalingGroupEnable:
    Type: ALIYUN::ESS::ScalingGroupEnable
    Properties:
      ScalingRuleArisExecuteVersion: '1'
      ScalingConfigurationId:
        Ref: EssInstanceScalingConfiguration
      InstanceIds:
        Fn::GetAtt:
          - EcsInstanceGroup
          - InstanceIds
      ScalingGroupId:
        Ref: EssInstanceScalingGroup

    Complete sample template

    ROSTemplateFormatVersion: '2015-09-01'
Description: { }
Parameters:
  EcsInstancePassword:
    NoEcho: true
    Type: String
    Description: The logon password for the server. It must be 8 to 30 characters in length and contain at least three of the following character types: uppercase letters, lowercase letters, digits, and special characters. Special characters include ()`~!@#$%^&*_-+=|{}[]:;'<>,.?/.
    AllowedPattern: '[0-9A-Za-z\_\-\&:;''<>,=%`~!@#\(\)\$\^\*\+\|\{\}\[\]\.\?\/]+$'
    Label: Instance Password
    ConstraintDescription: The password must be 8 to 30 characters in length and contain at least three of the following character types: uppercase letters, lowercase letters, digits, and special characters. Special characters include ()`~!@#$%^&*_-+=|{}[]:;'<>,.?/.
    MinLength: 8
    MaxLength: 30
Resources:
  Vpc:
    Type: ALIYUN::ECS::VPC
    Properties:
      CidrBlock: 192.168.0.0/16
      VpcName:
        Ref: ALIYUN::StackName
  VSwitch:
    Type: ALIYUN::ECS::VSwitch
    Properties:
      VSwitchName:
        Ref: ALIYUN::StackName
      VpcId:
        Ref: Vpc
      ZoneId:
        Fn::Select:
          - '0'
          - Fn::GetAZs:
              Ref: ALIYUN::Region
      CidrBlock: 192.168.0.0/24
  EcsSecurityGroup:
    Type: ALIYUN::ECS::SecurityGroup
    Properties:
      SecurityGroupName:
        Ref: ALIYUN::StackName
      VpcId:
        Ref: Vpc
      SecurityGroupEgress:
        - PortRange: '-1/-1'
          Priority: 1
          IpProtocol: all
          DestCidrIp: 0.0.0.0/0
          NicType: intranet
  EcsInstance:
    Type: ALIYUN::ECS::Instance
    Properties:
      VpcId:
        Ref: Vpc
      SecurityGroupId:
        Ref: EcsSecurityGroup
      VSwitchId:
        Ref: VSwitch
      ImageId: centos_7
      AllocatePublicIP: false
      InstanceType: ecs.c5.large
      SystemDiskSize: 40
      SystemDiskCategory: cloud_essd
      Password:
        Ref: EcsInstancePassword
  EssInstanceScalingGroup:
    Type: ALIYUN::ESS::ScalingGroup
    Properties:
      ScalingGroupName:
        Ref: ALIYUN::StackName
      RemovalPolicys:
        - NewestInstance
      MinSize: 3
      MaxSize: 50
      VSwitchId:
        Ref: VSwitch
      DefaultCooldown: 300
  EssInstanceScalingConfiguration:
    Type: ALIYUN::ESS::ScalingConfiguration
    Properties:
      SecurityGroupId:
        Ref: EcsSecurityGroup
      ScalingGroupId:
        Ref: EssInstanceScalingGroup
      ScalingConfigurationName:
        Fn::Sub: sc-${ALIYUN::StackName}
      InstanceType: ecs.c5.large
      SystemDiskCategory: cloud_essd
      SystemDiskSize: 200
      ImageId: centos_7_9_x64_20G_alibase_20220727.vhd
      InstanceName:
        Fn::Join:
          - '-'
          - - Ref: ALIYUN::StackName
            - '[1,4]'
  EssInstanceScalingGroupEnable:
    Type: ALIYUN::ESS::ScalingGroupEnable
    Properties:
      ScalingRuleArisExecuteVersion: '1'
      ScalingConfigurationId:
        Ref: EssInstanceScalingConfiguration
      InstanceIds:
        Fn::GetAtt:
          - EcsInstance
          - InstanceIds

    Add template parameter groups and dynamically get parameter configurations

    The preceding template defines resources and their dependencies, but properties such as `InstanceType` and `SystemDiskCategory` for `EcsInstance` use static values. You would need to modify the template every time you create stacks in a different region.

    To make the template more flexible and reusable, add a `Parameters` section.

    Add template parameter groups

    Use the `Metadata` section in the template to group parameters and define group labels.

    After you define the template resources and parameters, group the parameters by their corresponding resources as follows:

    Resource parameter categorization

    Resource name

    Parameter name

    Basic network configuration

    Vpc, VSwitch, EcsSecurityGroup

    VSwitchZoneId, VpcCidrBlock, VSwitchCidrBlock

    ECS configuration

    EcsInstance

    ECSInstanceType, ECSInstanceGroupCount, ECSImageId, ECSDiskCategory, EcsInstancePassword

    Scaling group resource configuration

    EssInstanceScalingGroup, EssInstanceScalingGroupEnable, EssInstanceScalingConfiguration

    ESSGroupMaxSize

    Dynamically get parameter settings

    Take `EcsInstanceType` as an example. To set filter conditions and dynamically select parameter values in the console, find the supported `AssociationProperty` value for the parameter. The value `ALIYUN::ECS::Instance::InstanceType` is documented under the `AssociationProperty` and `AssociationPropertyMetadata` section for the `ALIYUN::ECS::Instance` resource type, with `ZoneId` as the filter condition. For more information, see AssociationProperty and AssociationPropertyMetadata.

    Complete sample template

    ROSTemplateFormatVersion: '2015-09-01'
Description:
  en: An ECS deployment that supports auto scaling.
Parameters:
  VSwitchZoneId:
    Type: String
    AssociationProperty: ALIYUN::ECS::Instance::ZoneId
    Description:
      en: The zone ID of the vSwitch.
    Label:
      en: VSwitch Zone ID
  VpcCidrBlock:
    Default: 192.168.0.0/16
    Label:
      en: VPC CIDR Block
    Type: String
    Description:
      en: The CIDR block for the new VPC. We recommend that you use one of the following CIDR blocks:<font color='green'>[10.0.XX.XX/8]</font><br><font color='green'>[172.16.XX.XX/12]</font><br><font color='green'>[192.168.XX.XX/16]</font>
  VSwitchCidrBlock:
    Default: 192.168.0.0/24
    Type: String
    Description:
      en: The CIDR block must be a subnet of the VPC and must not be in use by another vSwitch.
    Label:
      en: VSwitch CIDR Block
  ECSInstanceType:
    Type: String
    Label:
      en: Instance Type
    AssociationProperty: ALIYUN::ECS::Instance::InstanceType
    AssociationPropertyMetadata:
      ZoneId: ${VSwitchZoneId}
      InstanceChargeType: ${InstanceChargeType}
  ECSDiskCategory:
    Type: String
    Description:
      en: '<font color=''blue''><b>Valid values:</font>[cloud_efficiency: <font color=''green''>ultra disk</font>]<br>[cloud_ssd: <font color=''green''>standard SSD</font>]<br>[cloud_essd: <font color=''green''>enterprise SSD</font>]<br>[cloud: <font color=''green''>basic disk</font>]<br>[ephemeral_ssd: <font color=''green''>local SSD</font>]'
    AssociationProperty: ALIYUN::ECS::Disk::SystemDiskCategory
    AssociationPropertyMetadata:
      ZoneId: ${VSwitchZoneId}
      InstanceType: ${ECSInstanceType}
    Label:
      en: System Disk Type
  ECSImageId:
    AssociationProperty: ALIYUN::ECS::Image::ImageId
    Label:
      en: Image ID
    Description:
      en: The ID of the image used to create the ECS instance. <font><a href='https://www.alibabacloud.com/help/doc-detail/112977.html' target='_blank'><b>View image resources</font color='blue'></a>
    Type: String
  EcsInstancePassword:
    NoEcho: true
    Type: String
    Description:
      en: The logon password for the server. The password must be 8 to 30 characters in length and contain characters from at least three of the following categories: uppercase letters, lowercase letters, digits, and special characters: ()`~!@#$%^&*_-+=|{}[]:;'<>,.?/.
    AllowedPattern: '[0-9A-Za-z\_\-\&:;''<>,=%`~!@#\(\)\$\^\*\+\|\{\}\[\]\.\?\/]+$'
    Label:
      en: Instance Password
    ConstraintDescription:
      en: The password must be 8 to 30 characters in length and contain characters from at least three of the following categories: uppercase letters, lowercase letters, digits, and special characters: ()`~!@#$%^&*_-+=|{}[]:;'<>,.?/.
    MinLength: 8
    MaxLength: 30
    AssociationProperty: ALIYUN::ECS::Instance::Password
  ECSInstanceGroupCount:
    Type: Number
    Description:
      en: The number of ECS instances.
    Label:
      en: Instance Count
    Default: 3
  ESSGroupMaxSize:
    Type: Number
    Label:
      en: The maximum number of ECS instances in the scaling group.
    Default: 50
Resources:
  Vpc:
    Type: ALIYUN::ECS::VPC
    Properties:
      CidrBlock:
        Ref: VpcCidrBlock
      VpcName:
        Ref: ALIYUN::StackName
  VSwitch:
    Type: ALIYUN::ECS::VSwitch
    Properties:
      VSwitchName:
        Ref: ALIYUN::StackName
      VpcId:
        Ref: Vpc
      ZoneId:
        Ref: VSwitchZoneId
      CidrBlock:
        Ref: VSwitchCidrBlock
  EcsSecurityGroup:
    Type: ALIYUN::ECS::SecurityGroup
    Properties:
      SecurityGroupName:
        Ref: ALIYUN::StackName
      VpcId:
        Ref: Vpc
      SecurityGroupIngress:
        - PortRange: 8080/8080
          Priority: 1
          SourceCidrIp: 0.0.0.0/0
          IpProtocol: tcp
          NicType: internet
      SecurityGroupEgress:
        - PortRange: '-1/-1'
          Priority: 1
          IpProtocol: all
          DestCidrIp: 0.0.0.0/0
          NicType: internet
        - PortRange: '-1/-1'
          Priority: 1
          IpProtocol: all
          DestCidrIp: 0.0.0.0/0
          NicType: intranet
  EcsInstanceGroup:
    Type: ALIYUN::ECS::InstanceGroup
    Properties:
      InstanceName:
        Fn::Join:
          - '-'
          - - Ref: ALIYUN::StackName
            - '[1,4]'
      VpcId:
        Ref: Vpc
      VSwitchId:
        Ref: VSwitch
      SecurityGroupId:
        Ref: EcsSecurityGroup
      SystemDiskCategory:
        Ref: ECSDiskCategory
      SystemDiskSize: 200
      MaxAmount:
        Ref: ECSInstanceGroupCount
      ImageId:
        Ref: ECSImageId
      InstanceType:
        Ref: ECSInstanceType
      Password:
        Ref: EcsInstancePassword
      AllocatePublicIP: false
  EssInstanceScalingGroupEnable:
    Type: ALIYUN::ESS::ScalingGroupEnable
    Properties:
      ScalingRuleArisExecuteVersion: '1'
      ScalingConfigurationId:
        Ref: EssInstanceScalingConfiguration
      InstanceIds:
        Fn::GetAtt:
          - EcsInstanceGroup
          - InstanceIds
      ScalingGroupId:
        Ref: EssInstanceScalingGroup
  EssInstanceScalingConfiguration:
    Type: ALIYUN::ESS::ScalingConfiguration
    Properties:
      SecurityGroupId:
        Ref: EcsSecurityGroup
      ScalingGroupId:
        Ref: EssInstanceScalingGroup
      ScalingConfigurationName:
        Fn::Sub: sc-${ALIYUN::StackName}
      InstanceType:
        Ref: ECSInstanceType
      SystemDiskCategory:
        Ref: ECSDiskCategory
      SystemDiskSize: 200
      ImageId:
        Ref: ECSImageId
      InstanceName:
        Fn::Join:
          - '-'
          - - Ref: ALIYUN::StackName
            - '[1,4]'
  EssInstanceScalingGroup:
    Type: ALIYUN::ESS::ScalingGroup
    Properties:
      ScalingGroupName:
        Ref: ALIYUN::StackName
      RemovalPolicys:
        - NewestInstance
      MinSize:
        Ref: ECSInstanceGroupCount
      MaxSize: 50
      VSwitchId:
        Ref: VSwitch
      DefaultCooldown: 300
Metadata:
  ALIYUN::ROS::Interface:
    ParameterGroups:
      - Parameters:
          - VSwitchZoneId
          - VpcCidrBlock
          - VSwitchCidrBlock
        Label:
          default:
            en: Basic Network Configuration
      - Parameters:
          - ECSInstanceType
          - ECSDiskCategory
          - ECSImageId
          - EcsInstancePassword
          - ECSInstanceGroupCount
        Label:
          default:
            en: ECS Instance Configuration
      - Parameters:
          - ESSGroupMaxSize
        Label:
          default:
            en: Scaling Group Configuration