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    Resource Orchestration Service:Use Count to create multiple resources at a time

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    Resource Orchestration Service:Use Count to create multiple resources at a time

    Last Updated:Feb 01, 2024

    Resource Orchestration Service (ROS) provides the Count feature that allows you to create multiple resources at a time. This topic describes how to use Count to create multiple Elastic Compute Service (ECS) instances and elastic IP addresses (EIPs) at a time and bind the EIPs to the ECS instances.

    Background information

    ALIYUN::VPC::EIP is used to apply for EIPs. If you use a template to apply for multiple EIPs at a time, you must specify multiple ALIYUN::VPC::EIP resources in the template. This makes the template long-winded. In this case, you can use Count in the template to efficiently create multiple resources at a time. For more information about Count, see Count. When you use Count to create multiple resources at a time, you can specify the DependsOn property and the ParallelCount parameter to control concurrency during the resource creation.

    Step 1: Create a template

    You can use Count to create a template and use the template to create the following resources:

    • One virtual private cloud (VPC)

    • One vSwitch

    • One security group

    • Four pay-as-you-go ECS instances

    • Four EIPs

    The following sections provide the sample code and the description of the template.

    • Sample code:

      ROSTemplateFormatVersion: '2015-09-01'
Parameters:
  Count:
    Type: Number
    Default: 4
  ZoneId:
    Type: String
  InstanceType:
    Type: String
    Default: ecs.c6.large
  Password:
    Type: String
    Default: Abc1****
    NoEcho: true
  ParallelCount:
    Type: Number
    Default: 2
  SystemDiskCategory:
    Type: String
Resources:
  Vpc:
    Type: ALIYUN::ECS::VPC
    Properties:
      CidrBlock: 10.0.0.0/8
      VpcName: test-resource-count
  VSwitch:
    Type: ALIYUN::ECS::VSwitch
    Properties:
      CidrBlock: 10.0.10.0/24
      ZoneId:
        Ref: ZoneId
      VpcId:
        Ref: Vpc
  SecurityGroup:
    Type: ALIYUN::ECS::SecurityGroup
    Properties:
      SecurityGroupName: test-resource-count
      VpcId:
        Ref: Vpc
  Eip:
    Type: ALIYUN::VPC::EIP
    Count:
      Ref: Count
    DependsOn:
      Fn::Select:
        - Fn::Calculate:
            - 1-{0}//{1}
            - 0
            - - Fn::Min:
                  - Ref: ALIYUN::Index
                  - Ref: ParallelCount
              - Ref: ParallelCount
        - - Fn::Replace:
              - index:
                  Fn::Calculate:
                    - '{0}-{1}'
                    - 0
                    - - Ref: ALIYUN::Index
                      - Ref: ParallelCount
              - Eip[index]
    Properties:
      Bandwidth: 5
  Servers:
    Type: ALIYUN::ECS::InstanceGroup
    Properties:
      ImageId: centos_7
      InstanceType:
        Ref: InstanceType
      VpcId:
        Ref: Vpc
      VSwitchId:
        Ref: VSwitch
      SecurityGroupId:
        Ref: SecurityGroup
      Password:
        Ref: Password
      AllocatePublicIP: false
      MaxAmount:
        Ref: Count
      SystemDiskCategory:
        Ref: SystemDiskCategory
  EipBind:
    Type: ALIYUN::VPC::EIPAssociation
    Count:
      Ref: Count
    DependsOn:
      Fn::Select:
        - Fn::Calculate:
            - 1-{0}//{1}
            - 0
            - - Fn::Min:
                  - Ref: ALIYUN::Index
                  - Ref: ParallelCount
              - Ref: ParallelCount
        - - Fn::Replace:
              - index:
                  Fn::Calculate:
                    - '{0}-{1}'
                    - 0
                    - - Ref: ALIYUN::Index
                      - Ref: ParallelCount
              - EipBind[index]
    Properties:
      InstanceId:
        Fn::Select:
          - Ref: ALIYUN::Index
          - Fn::GetAtt:
              - Servers
              - InstanceIds
      AllocationId:
        Fn::Select:
          - Ref: ALIYUN::Index
          - Ref: Eip
Outputs:
  InstanceIds:
    Value:
      Fn::GetAtt:
        - Servers
        - InstanceIds
  AllocationIds:
    Value:
      Ref: Eip
  EipAddresses:
    Value:
      Fn::GetAtt:
        - Eip
        - EipAddress

    • Description:

      • You can use the following template fragment to create four EIPs.

        Set the Count parameter to 4 and the ParallelCount parameter to 2. In this case, four EIPs are created in two batches. After ROS preprocesses the template, four EIPs are generated in two batches. In the first batch, Eip[0] and Eip[1] are generated. In the second batch, Eip[2] and Eip[3] are generated. 

        Eip:
  Type: ALIYUN::VPC::EIP
  Count:
    Ref: Count
  DependsOn:
    Fn::Select:
      - Fn::Calculate:
          - 1-{0}//{1}
          - 0
          - - Fn::Min:
                - Ref: ALIYUN::Index
                - Ref: ParallelCount
            - Ref: ParallelCount
      - - Fn::Replace:
            - index:
                Fn::Calculate:
                  - '{0}-{1}'
                  - 0
                  - - Ref: ALIYUN::Index
                    - Ref: ParallelCount
            - Eip[index]
  Properties:
    Bandwidth: 5

      • You can use the following template fragment to create four ECS instances.

        Set the Count parameter to 4 and reference the Count parameter in the MaxAmount property of ALIYUN::ECS::InstanceGroup. In this case, four ECS instances are created. 

        Servers:
  Type: ALIYUN::ECS::InstanceGroup
  Properties:
    ImageId: centos_7
    InstanceType:
      Ref: InstanceType
    VpcId:
      Ref: Vpc
    VSwitchId:
      Ref: VSwitch
    SecurityGroupId:
      Ref: SecurityGroup
    Password:
      Ref: Password
    AllocatePublicIP: false
    MaxAmount:
      Ref: Count
    SystemDiskCategory:
      Ref: SystemDiskCategory

      • You can use the following template fragment to create four EipBind resources and use the ALIYUN::Index pseudo parameter to bind the EIPs to the ECS instances one by one.

        Set the Count parameter to 4 and the ParallelCount parameter to 2. In this case, four EipBind resources are created in two batches. After ROS preprocesses the template, four EipBind resources are generated in two batches. In the first batch, EipBind[0] and EipBind[1] are generated. In the second batch, EipBind[2] and EipBind[3] are generated. Then, reference ALIYUN::Index is in Count. When ROS preprocesses the template, ROS replaces ALIYUN::Index with numeric values. In this example, Eip[0] is bound to the first ECS instance, Eip[1] is bound to the second ECS instance, Eip[2] is bound to the third ECS instance, and Eip[3] is bound to the fourth ECS instance. 

        EipBind:
  Type: ALIYUN::VPC::EIPAssociation
  Count:
    Ref: Count
  DependsOn:
    Fn::Select:
      - Fn::Calculate:
          - 1-{0}//{1}
          - 0
          - - Fn::Min:
                - Ref: ALIYUN::Index
                - Ref: ParallelCount
            - Ref: ParallelCount
      - - Fn::Replace:
            - index:
                Fn::Calculate:
                  - '{0}-{1}'
                  - 0
                  - - Ref: ALIYUN::Index
                    - Ref: ParallelCount
            - EipBind[index]
  Properties:
    InstanceId:
      Fn::Select:
        - Ref: ALIYUN::Index
        - Fn::GetAtt:
            - Servers
            - InstanceIds
    AllocationId:
      Fn::Select:
        - Ref: ALIYUN::Index
        - Ref: Eip

    Step 2: Create a stack

    1. Log on to the ROS console.

    2. In the left-side navigation pane, click Stacks.

    3. In the top navigation bar, select the region where you want to create a stack from the region drop-down list. For example, you can select China (Hangzhou).

    4. On the Stacks page, click Create Stack and select Use ROS from the drop-down list.

    5. In the Specify Template section of the Select Template step, select Select an Existing Template.

    6. Set the Template Import Method parameter to Enter Template Content, enter the content of the template that you created in Step 1: Create a template, and then click Next.

    7. In the Configure Parameters step, specify the Stack Name parameter and configure parameters in the Configure Template Parameters section.

    8. In the Configure Stack Settings section, follow on-screen instructions to configure the Stack Policy, Rollback on Failure, Timeout Period, Deletion Protection, RAM Role, Tags, and Resource Group parameters. Then, click Next.

      If the resources are not created or updated within the time that is specified by the Timeout Period parameter, the system considers the operation failed. Then, the system determines whether to roll back the resources to the state before they are created or updated based on the value of the Rollback on Failure parameter.

    9. In the Compliance Precheck step, complete the compliance precheck and click Next.

      Note

      The compliance precheck feature is available only for specific resources. For more information, see Compliance precheck of ROS.

      1. In the Evaluate Rules section, add compliance rules.

        You can add compliance rules based on the cloud resources in the ROS template.

      2. Click Evaluate.

        You can modify the template content based on the suggestions that are provided to remediate invalid resources to ensure the compliance of the resources.

    10. In the Check and Confirm step, click Create.

    Step 3: (Optional) View the resources and template

    After the stack is created, you can view the information about the resources and the template that are preprocessed by ROS on the stack details page.

    1. On the stack details page, click the Resources tab to view the information about the resources.

    2. On the stack details page, click the Template tab to view the information about the template.

      The following sample code provides an example of the preprocessed template:

      ROSTemplateFormatVersion: '2015-09-01'
Resources:
  EipBind[1]:
    Type: ALIYUN::VPC::EIPAssociation
    Properties:
      InstanceId:
        Fn::Select:
          - 1
          - Fn::GetAtt:
              - Servers
              - InstanceIds
      AllocationId:
        Ref: Eip[1]
  Eip[1]:
    Type: ALIYUN::VPC::EIP
    Properties:
      Bandwidth: 5
  SecurityGroup:
    Type: ALIYUN::ECS::SecurityGroup
    Properties:
      VpcId:
        Ref: Vpc
      SecurityGroupName: test-resource-count
  Servers:
    Type: ALIYUN::ECS::InstanceGroup
    Properties:
      SystemDiskCategory:
        Ref: SystemDiskCategory
      VpcId:
        Ref: Vpc
      SecurityGroupId:
        Ref: SecurityGroup
      ImageId: centos_7
      AllocatePublicIP: false
      VSwitchId:
        Ref: VSwitch
      Password:
        Ref: Password
      InstanceType:
        Ref: InstanceType
      MaxAmount:
        Ref: Count
  Eip[2]:
    Type: ALIYUN::VPC::EIP
    Properties:
      Bandwidth: 5
    DependsOn: Eip[0]
  Eip[0]:
    Type: ALIYUN::VPC::EIP
    Properties:
      Bandwidth: 5
  Vpc:
    Type: ALIYUN::ECS::VPC
    Properties:
      VpcName: test-resource-count
      CidrBlock: 10.0.0.0/8
  Eip[3]:
    Type: ALIYUN::VPC::EIP
    Properties:
      Bandwidth: 5
    DependsOn: Eip[1]
  VSwitch:
    Type: ALIYUN::ECS::VSwitch
    Properties:
      VpcId:
        Ref: Vpc
      CidrBlock: 10.0.10.0/24
      ZoneId:
        Ref: ZoneId
  EipBind[3]:
    Type: ALIYUN::VPC::EIPAssociation
    Properties:
      InstanceId:
        Fn::Select:
          - 3
          - Fn::GetAtt:
              - Servers
              - InstanceIds
      AllocationId:
        Ref: Eip[3]
    DependsOn: EipBind[1]
  EipBind[0]:
    Type: ALIYUN::VPC::EIPAssociation
    Properties:
      InstanceId:
        Fn::Select:
          - 0
          - Fn::GetAtt:
              - Servers
              - InstanceIds
      AllocationId:
        Ref: Eip[0]
  EipBind[2]:
    Type: ALIYUN::VPC::EIPAssociation
    Properties:
      InstanceId:
        Fn::Select:
          - 2
          - Fn::GetAtt:
              - Servers
              - InstanceIds
      AllocationId:
        Ref: Eip[2]
    DependsOn: EipBind[0]
Parameters:
  Count:
    Default: 4
    Type: Number
  SystemDiskCategory:
    Type: String
  ZoneId:
    Type: String
  Password:
    Default: Abc1****
    NoEcho: true
    Type: String
  InstanceType:
    Default: ecs.c6.large
    Type: String
  ParallelCount:
    Default: 2
    Type: Number
Outputs:
  AllocationIds:
    Value:
      - Ref: Eip[0]
      - Ref: Eip[1]
      - Ref: Eip[2]
      - Ref: Eip[3]
  InstanceIds:
    Value:
      Fn::GetAtt:
        - Servers
        - InstanceIds
  EipAddresses:
    Value:
      - Fn::GetAtt:
          - Eip[0]
          - EipAddress
      - Fn::GetAtt:
          - Eip[1]
          - EipAddress
      - Fn::GetAtt:
          - Eip[2]
          - EipAddress
      - Fn::GetAtt:
          - Eip[3]
          - EipAddress