Attaches server groups to a scaling group. To seamlessly adjust the number of instances in response to changes in your business workload or to maintain the uninterrupted accessibility of your application, you can call the AttachServerGroups operation. By attaching Application Load Balancer (ALB), Network Load Balancer (NLB), or Gateway Load Balancer (GWLB) server groups to your scaling group, this operation enables Auto Scaling to automatically tailor your computing capacity to your business needs. Furthermore, it optimizes traffic routing by dynamically allocating incoming requests based on current workload patterns, which significantly improves the stability and performance of your application.
Debugging
Authorization information
The following table shows the authorization information corresponding to the API. The authorization information can be used in the Action policy element to grant a RAM user or RAM role the permissions to call this API operation. Description:
- Operation: the value that you can use in the Action element to specify the operation on a resource.
- Access level: the access level of each operation. The levels are read, write, and list.
- Resource type: the type of the resource on which you can authorize the RAM user or the RAM role to perform the operation. Take note of the following items:
- For mandatory resource types, indicate with a prefix of * .
- If the permissions cannot be granted at the resource level,
All Resourcesis used in the Resource type column of the operation.
- Condition Key: the condition key that is defined by the cloud service.
- Associated operation: other operations that the RAM user or the RAM role must have permissions to perform to complete the operation. To complete the operation, the RAM user or the RAM role must have the permissions to perform the associated operations.
| Operation | Access level | Resource type | Condition key | Associated operation |
|---|---|---|---|---|
| ess:AttachServerGroups | update | *ScalingGroup acs:ess:{#regionId}:{#accountId}:scalinggroup/{#ScalingGroupId} |
| none |
Request parameters
| Parameter | Type | Required | Description | Example |
|---|---|---|---|---|
| RegionId | string | Yes | The region ID of the scaling group. | cn-hangzhou |
| ScalingGroupId | string | Yes | The ID of the scaling group. | asg-bp1fo0dbtsbmqa9h**** |
| 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 Ensure idempotence. | 123e4567-e89b-12d3-a456-42665544**** |
| ForceAttach | boolean | No | Specifies whether to add the existing Elastic Compute Service (ECS) instances or elastic container instances (ECI) in the scaling group to the server group. Valid values:
Default value: false. | false |
| ServerGroups | array<object> | Yes | The information about the server groups. | |
| object | Yes | The information about the server group. | ||
| ServerGroupId | string | Yes | The ID of the server group. | sgp-5yc3bd9lfyh***** |
| Type | string | Yes | The type of the server group. Valid Values:
| ALB |
| Weight | integer | No | The weight of an ECS or ECI instance as a backend server of the server group. Valid values: 0 to 100 If you assign a higher weight to an instance, the instance is allocated a larger proportion of access requests. If the weight is 0, the ECS or ECI instance does not receive access requests. Note
For ALB and NLB types, this parameter is required. GWLB type cannot be set.
| 100 |
| Port | integer | No | The port used by ECS or ECI instances after being added as backend servers to the server group. Valid values: 1 to 65535. Note
For ALB and NLB types, this parameter is required. GWLB type cannot set this parameter and the default value is 6081.
| 22 |
Response parameters
Examples
Sample success responses
JSONformat
{
"ScalingActivityId": "asa-bp1c9djwrgxjyk31****",
"RequestId": "473469C7-AA6F-4DC5-B3DB-A3DC0DE3****"
}Error codes
For a list of error codes, visit the Service error codes.
Change history
| Change time | Summary of changes | Operation |
|---|---|---|
| 2025-12-25 | The internal configuration of the API is changed, but the call is not affected | View Change Details |
| 2025-03-14 | API Description Update | View Change Details |
| 2023-12-18 | The internal configuration of the API is changed, but the call is not affected | View Change Details |