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Server Load Balancer:AddServersToServerGroup

Last Updated:Jan 21, 2026

Adds backend servers to a server group.

Operation description

AddServersToServerGroup is an asynchronous operation. After you send a request, the system returns a request ID, but the backend servers are not added immediately. The system adds the servers in the background.

  1. Call ListServerGroups to query the status of the server group:

  • If the server group is in the Configuring state, the configuration of 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 servers:

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

  • If a backend server is in the Available state, it 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 ID of the server group.

sgp-atstuj3rtop****

Servers

array<object>

Yes

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

object

No

The backend server.

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. You do not need to set this parameter when ServerType is set to Fc.

80

ServerId

string

No

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

  • If the server group is of the Instance type, set this parameter to the ID of an ECS instance, an ENI, or an ECI instance.

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

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

i-uf616vu8me******

ServerIp

string

No

The IP address of the backend server. You can add up to 200 servers in a single call.

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

Note

You do not need to set this parameter when ServerType is set to Fc.

192.168.1.1

ServerType

string

Yes

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

  • Ecs: an ECS instance.

  • Eni: an ENI.

  • Eci: an ECI.

  • Ip: an IP address.

  • Fc: a function in Function Compute.

Ecs

Weight

integer

No

The weight of the backend server. Valid values: 0 to 100. Default value: 100. If you set the weight to 0, no requests are forwarded to the backend server. You can add up to 200 servers in a single call.

Note

You do not need to set this parameter 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 token on your client to 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 request as the ClientToken. The RequestId of each API request may be different.

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 required parameters, request format, and service limits. If the request fails the dry run, an error is returned. If the request passes the dry run, the DryRunOperation error code is returned. In a dry run, no backend servers are added.

  • false (default): sends the request. If the request passes the check, a 2xx HTTP status code is returned and the operation is performed.

false

Response elements

Element

Type

Description

Example

object

The returned data.

JobId

string

The ID of the asynchronous task.

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.