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Server Load Balancer:AddServersToServerGroup

Last Updated:Jul 13, 2026

Adds backend servers to a server group.

Operation description

AddServersToServerGroup is an asynchronous operation. After a request ID is returned, the backend server may not be added yet because the system is still processing the task in the background.

  1. Call ListServerGroups to query the status of the 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.

  1. Call ListServerGroupServers to query the status of the backend server:

  • If the backend server is in the Adding state, the backend server is being added to the server group.

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

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Test

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:AddServersToServerGroup

create

*ServerGroup

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

Instance

acs:alb:{#regionId}:{#accountId}:ecs/{#InstanceId}

NetworkInterface

acs:alb:{#regionId}:{#accountId}:eni/{#NetworkInterfaceId}

ContainerGroup

acs:alb:{#regionId}:{#accountId}:eci/{#ContainerGroupId}

None None

Request parameters

Parameter

Type

Required

Description

Example

ServerGroupId

string

Yes

The server group ID.

sgp-atstuj3rtop****

Servers

array<object>

Yes

The list of backend servers. You can add up to 200 servers in a single call.

object

No

The backend server group struct.

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. You can add up to 200 servers in a single call.

Note

This parameter is required when ServerType is set to Ecs, Eni, Eci, or Ip. This parameter is not required when ServerType is set to Fc.

80

ServerId

string

No

The backend server ID. You can add up to 200 servers in a single call.

  • If the server group is of the Instance type, this parameter specifies the resource ID of an Ecs, Eni, or Eci instance.

  • If the server group is of the Ip type, this parameter specifies an IP address.

  • If the server group is of the Fc type, this parameter specifies the Alibaba Cloud Resource Name (ARN) of a Function Compute function.

i-uf616vu8me******

ServerIp

string

No

The IP address. You can add up to 200 servers in a single call.

When ServerType is set to Eni, you can specify the primary private IP address or a secondary private IP address of the ENI.

Note

This parameter is not required when ServerType is set to Fc.

192.168.1.1

ServerType

string

Yes

The server type of the backend server. You can add up to 200 servers in a single invoke. Valid values:

  • Ecs: ECS instance.

  • Eni: ENI network interface controller (NIC) instance.

  • Eci: 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 add up to 200 servers in a single call.

Note

This parameter is not required when ServerType is set to Fc.

100

RemoteIpEnabled

boolean

No

Specifies whether to enable the remote IP feature. You can add up to 200 servers in a single call. Valid values:

  • true: enabled.

  • false: disabled.

Note

This parameter takes effect only when ServerType is set to Ip.

false

ClientToken

string

No

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

Generate a parameter value from your client to ensure uniqueness across different requests. ClientToken supports only ASCII characters.

Note

If you do not specify this parameter, the system uses the RequestId of the API request as the ClientToken. The RequestId may differ 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 without adding backend servers to the server group. The system checks the required parameters, request format, and service limits. If the check fails, the corresponding error is returned. If the check succeeds, the error code DryRunOperation is returned.

  • false (default): performs a dry run and sends the request. If the check succeeds, an HTTP 2xx status code is returned and the operation is 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.

365F4154-92F6-4AE4-92F8-7FF34******

Examples

Success response

JSON format

{
  "JobId": "72dcd26b-f12d-4c27-b3af-18f6aed5****",
  "RequestId": "365F4154-92F6-4AE4-92F8-7FF34******"
}

Error codes

HTTP status code

Error code

Error message

Description

400 ResourceQuotaExceeded.ServerAddedNum The quota of %s is exceeded for resource %s, usage %s/%s.
400 IncorrectStatus.ServerGroup The status of %s [%s] is incorrect. The status of %s [%s] is incorrect.
400 Conflict.BackendServer There is already %s having the same configuration with %s.
400 OperationDenied.VpcVportNotFound The operation is not allowed because of %s. The operation is not allowed because of %s.
400 IncorrectStatus.Eni The status of %s [%s] is incorrect. The status of %s [%s] is incorrect.
400 ResourceInUse.IP The specified resource %s is in use. The specified resource %s is in use.
400 OperationDenied.NoAvailableVSwitch The operation is not allowed because of %s. The operation is not allowed because of %s.
400 OperationDenied.VgwVipNotFound The operation is not allowed because of %s. The operation is not allowed because of %s.
400 OperationDenied.CloudBox The operation is not allowed because of %s. The operation is not allowed because of %s.
400 Mismatch.Type The %s is mismatched for %s and %s. The %s is mismatched for %s and %s.
400 Mismatch.VpcId The %s is mismatched for %s and %s. The %s is mismatched for %s and %s.
400 ResourceQuotaExceeded.LoadBalancerServersNum The quota of %s is exceeded for resource %s, usage %s/%s.
400 ResourceInConfiguring The specified resource of %s is being configured. Please try again later.
400 DuplicatedParam.BackendServer The param of %s is duplicated. The param of %s is duplicated.
400 OperationDenied.EciNotSupportJobType The operation is not allowed because of eci not support job type. The operation is not allowed because of eci not support job type.
400 IllegalParam.ServerIp The param of ServerIp is illegal.
400 Mismatch.ServerType The %s is mismatched for %s and %s.
400 ServiceUnavailable The request has failed due to a temporary failure of the server. The request has failed due to a temporary failure of the server.
403 Forbidden.ServerGroup Authentication has failed for ServerGroup.
404 ResourceNotFound.ServerGroup The specified resource %s is not found.
404 ResourceNotFound.Ecs The specified resource %s is not found.
404 ResourceNotFound.Eci The specified resource %s is not found.
404 ResourceNotFound.Eni The specified resource %s is not found. The specified resource %s is not found.

See Error Codes for a complete list.

Release notes

See Release Notes for a complete list.