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    Auto Scaling:AttachVServerGroups

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    Auto Scaling:AttachVServerGroups

    Last Updated:Sep 17, 2026

    Adds one or more virtual server groups to a load balancing instance associated with a scaling group.

    Operation description

    Operation description

    • To add virtual server groups to a scaling group, the following conditions must be met:

      • The load balancing instance and the scaling group must belong to the same account.

      • The load balancing instance and the scaling group must be in the same region.

      • The load balancing instance must be in the Running state.

      • The load balancing instance must have at least one listener configured, and health check must be enabled.

      • If both the load balancing instance and the scaling group are of the VPC network type, they must be in the same VPC.

      • If the scaling group is of the VPC network type and the load balancing instance is of the classic network type, and the virtual server group contains a VPC-connected instance, the instance must be in the same VPC as the scaling group.

      • The virtual server groups to be added must belong to the corresponding load balancing instance.

      • The number of virtual server groups in the scaling group cannot exceed the quota. For more information about the quota, see Limits.

    • When you add virtual server groups to a scaling group, you must specify the following properties:

      • Load balancing instance ID (LoadBalancerId)

      • Virtual server group ID (VServerGroupId)

      • Virtual server group port number (Port)

      Note

      If you add the same virtual server group to a scaling group by using different port numbers, the virtual server group is considered as multiple virtual server groups in the scaling group. If the virtual server group ID and port number are both duplicated in the request parameters, the first configured group is used by default, and the remaining virtual server groups are ignored.

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    RAM authorization

    The table below describes the authorization required to call this API. You can define it in a Resource Access Management (RAM) policy. The table's columns are detailed below:

    • Action: The actions can be used in the Action element of RAM permission policy statements to grant permissions to perform the operation.

    • API: The API that you can call to perform the action.

    • Access level: The predefined level of access granted for each API. Valid values: create, list, get, update, and delete.

    • Resource type: The type of the resource that supports authorization to perform the action. It indicates if the action supports resource-level permission. The specified resource must be compatible with the action. Otherwise, the policy will be ineffective.

      • For APIs with resource-level permissions, required resource types are marked with an asterisk (*). Specify the corresponding Alibaba Cloud Resource Name (ARN) in the Resource element of the policy.

      • For APIs without resource-level permissions, it is shown as All Resources. Use an asterisk (*) in the Resource element of the policy.

    • Condition key: The condition keys defined by the service. The key allows for granular control, applying to either actions alone or actions associated with specific resources. In addition to service-specific condition keys, Alibaba Cloud provides a set of common condition keys applicable across all RAM-supported services.

    • Dependent action: The dependent actions required to run the action. To complete the action, the RAM user or the RAM role must have the permissions to perform all dependent actions.

    Action

    Access level

    Resource type

    Condition key

    Dependent action

    ess:AttachVServerGroups

    update

    *ScalingGroup

    acs:ess:{#regionId}:{#accountId}:scalinggroup/{#ScalingGroupId}

    		 None None

    Request parameters

    Parameter

    Type

    Required

    Description

    Example
    RegionId

    string

    Yes

    The ID of the region where the scaling group resides, such as cn-hangzhou or cn-shanghai. For more information, see Regions and zones.

    cn-hangzhou
    ScalingGroupId

    string

    Yes

    The ID of the scaling group.

    asg-bp18p2yfxow2dloq****
    ClientToken

    string

    No

    The client token that is used to ensure the idempotence of the request.

    You can use the client to generate the token, but you must make sure that the token is unique among different requests. The token can contain only ASCII characters and cannot exceed 64 characters in length. For more information, see How to ensure idempotence.

    123e4567-e89b-12d3-a456-42665544****
    ForceAttach

    boolean

    No

    Specifies whether to add the existing ECS instances or elastic container instances in the scaling group to the new virtual server groups.

    • true: Adds the instances.

    • false: Does not add the instances.

    Default value: false.

    false
    VServerGroup

    array<object>

    Yes

    The information about the virtual server groups associated with the scaling group.

    array<object>

    No

    The information about the virtual server groups associated with the scaling group.

    VServerGroupAttribute

    array<object>

    No

    The properties of the virtual server group.

    object

    No

    The properties of the virtual server group.

    VServerGroupId

    string

    No

    The ID of the virtual server group. In this parameter:

    • The first N specifies the load balancing instance number. Valid values: 1 to 5.

    • The second N specifies the virtual server group number under the load balancing instance. Valid values: 1 to 5.

    rsp-bp1jp1rge****
    Weight

    integer

    No

    The weight that Auto Scaling sets when it adds ECS instances or elastic container instances to the virtual server group. Valid values: 0 to 100. In this parameter:

    • The first N specifies the load balancing instance number. Valid values: 1 to 5.

    • The second N specifies the virtual server group number under the load balancing instance. Valid values: 1 to 5.

    Default value: 50.

    100
    Port

    integer

    No

    The port number that Auto Scaling uses when it adds ECS instances or elastic container instances to the virtual server group. Valid values: 1 to 65535. In this parameter:

    • The first N specifies the load balancing instance number. Valid values: 1 to 5.

    • The second N specifies the virtual server group number under the load balancing instance. Valid values: 1 to 5.

    22
    LoadBalancerId

    string

    No

    The ID of the load balancing instance to which the virtual server group belongs. N specifies the load balancing instance number. Valid values: 1 to 5.

    lb-bp1u7etiogg38yvwz****

    Response elements

    Element

    Type

    Description

    Example

    object

    RequestId

    string

    The request ID.

    473469C7-AA6F-4DC5-B3DB-A3DC0DE3****

    Examples

    Success response

    JSON format

    {
  "RequestId": "473469C7-AA6F-4DC5-B3DB-A3DC0DE3****"
}

    Error codes

    See Error Codes for a complete list.

    Release notes

    See Release Notes for a complete list.