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    Server Load Balancer:UpdateServerGroupServersAttribute

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    Server Load Balancer:UpdateServerGroupServersAttribute

    Last Updated:Jul 13, 2026

    Updates the configurations of backend servers in a server group, such as weights and descriptions.

    Operation description

    UpdateServerGroupServersAttribute is an asynchronous operation. After a request is sent, the system returns a request ID. However, the backend server configurations are not yet updated, and the update task is still running in the background.

    1. You can call ListServerGroups to query the status of a server group:

      • If the server group is in the Configuring state, the server group is being modified.

      • If the server group is in the Available state, the server group is running.

    2. You can call ListServerGroupServers to query the status of a backend server:

      • If the backend server is in the Configuring state, the backend server is being modified.

      • If the backend server is in the Available state, the backend server is running.

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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

    alb:UpdateServerGroupServersAttribute

    update

    *ServerGroup

    acs:alb:{#regionId}:{#accountId}:servergroup/{#servergroupId}

    *Instance

    acs:ecs:{#regionId}:{#accountId}:ecs/{#ecsId}

    		 None None

    Request parameters

    Parameter

    Type

    Required

    Description

    Example
    ServerGroupId

    string

    Yes

    The server group ID.

    sgp-atstuj3rtop****
    Servers

    array<object>

    Yes

    The backend server group list. You can specify up to 40 servers in a single invoke.

    object

    No

    The backend server group structure.

    Description

    string

    No

    The description of the backend server. The description must be 2 to 256 characters in length and cannot start with http:// or https://.

    test
    Port

    integer

    No

    The port used by the backend server. Valid values: 1 to 65535.

    Note

    This parameter does not take effect when ServerType is set to Fc.

    80
    ServerId

    string

    No

    The backend server ID.

    • If ServerType is set to Ecs, Eni, or Eci, this parameter specifies the resource ID of the ECS instance, ENI, or ECI.

    • If ServerType is set to Ip, this parameter specifies the IP address.

    • If ServerType is set to Fc, this parameter specifies the ARN of the function.

    i-bp1f9kdprbgy9uiu****
    ServerIp

    string

    No

    The IP address.

    192.168.1.1
    ServerType

    string

    Yes

    The server type of the backend server. Valid values:

    • Ecs: ECS instance.

    • Eni: network interface controller (NIC).

    • Eci: elastic container instance.

    • Ip: IP address.

    • Fc: Function Compute.

    Ecs
    Weight

    integer

    No

    The weight of the backend server. Valid values: 0 to 100. Default value: 100. If the weight is set to 0, no requests are forwarded to the backend server. You can specify up to 40 servers in a single request.

    Note

    This parameter does not take effect when ServerType is set to Fc.

    100
    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.

    Note

    If you do not specify this parameter, the system automatically uses the RequestId of the API request as the ClientToken. The RequestId may be different for each API request.

    593B0448-D13E-4C56-AC0D-FDF0******
    DryRun

    boolean

    No

    Specifies whether to perform a dry run. Valid values:

    • true: performs a dry run. The system checks the request for potential issues, including missing parameter values, incorrect request format, and service limits. If the request fails the dry run, an error code is returned. If the request passes the dry run, the DryRunOperation error code is returned.

    • false (default): sends a Normal request, passes the dry run, and returns an HTTP 2xx status code. The operation to update the weight and description of the backend server in the server group is directly performed.

    false

    Response elements

    Element

    Type

    Description

    Example

    object

    The response struct.

    JobId

    string

    The asynchronous task ID.

    72dcd26b-f12d-4c27-b3af-18f6aed5****
    RequestId

    string

    The request ID.

    365F4154-92F6-4AE4-92F8-7FF3*****

    Examples

    Success response

    JSON format

    {
  "JobId": "72dcd26b-f12d-4c27-b3af-18f6aed5****",
  "RequestId": "365F4154-92F6-4AE4-92F8-7FF3*****"
}

    Error codes

    HTTP status code

    Error code

    Error message

    Description
    400 IncorrectStatus.ServerGroup The status of %s [%s] is incorrect. The status of %s [%s] is incorrect.
    400 ResourceInConfiguring The specified resource of %s is being configured. Please try again later.
    403 Forbidden.ServerGroup Authentication has failed for ServerGroup.
    404 ResourceNotFound.ServerGroup The specified resource %s is not found.
    404 ResourceNotFound.BackendServer The specified resource %s is not found.

    See Error Codes for a complete list.

    Release notes

    See Release Notes for a complete list.