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Server Load Balancer:CreateMasterSlaveServerGroup

Last Updated:Mar 02, 2026

Creates a primary/secondary server group. Each primary/secondary server group consists of two backend servers. One backend server functions as the primary server, and the other backend server functions as the secondary backend server.

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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

slb:CreateMasterSlaveServerGroup

create

Instance

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

*LoadBalancer

acs:slb:{#regionId}:{#accountId}:loadbalancer/{#LoadBalancerId}

  • slb:tag
None

Request parameters

Parameter

Type

Required

Description

Example

RegionId

string

Yes

The region ID of the Classic Load Balancer (CLB) instance.

cn-hangzhou

LoadBalancerId

string

Yes

The CLB instance ID.

lb-bp1hv944r69al4j******

MasterSlaveServerGroupName

string

No

The name of the primary/secondary server group.

Group1

MasterSlaveBackendServers

string

No

The backend servers in the primary/secondary server group. Each primary/secondary server group consists of two backend servers.

Configure the following parameters:

  • ServerId: required. The IDs of the backend servers. Specify the IDs in a string. You can specify the IDs of Elastic Compute Service (ECS) instances, elastic network interfaces (ENIs), and elastic container instances. If you set ServerId to the IDs of ENIs or elastic container instances, you must configure the Type parameter.

  • Weight: the weight of the backend server. Valid values: 0 to 100. Default value: 100. If you set the weight of a backend server to 0, no requests are forwarded to the backend server.

  • Description: optional. The description of the backend servers. Specify the description in a string. The description must be 1 to 80 characters in length, and can contain letters, digits, hyphens (-), forward slashes (/). periods (.), and underscores (_).

  • Type: the type of the backend server. Valid values:

    • ecs (default): ECS instance

    • eni: ENI

    • eci: elastic container instance

Note

You can specify ENIs and elastic container instances as backend servers only for high-performance CLB instances.

  • ServerIp: the IP address of the ENI or elastic container instance.

  • Port: the backend port.

  • ServerType: Specify the primary and secondary backend servers in a string. Valid values:

    • Master: primary server

    • Slave: secondary server

[{ "ServerId": "i-xxxxxxxxx", "Weight": "100", "Type": "ecs", "Port":"82","ServerType":"Master","Description":"test-112" }, { "ServerId": "i-xxxxxxxxx", "Weight": "100", "Type": "ecs", "Port":"84","ServerType":"Slave","Description":"test-112" }]

Tag

array<object>

No

The tags.

object

No

Key

string

No

The key of tag N. Valid values of N: 1 to 20. The tag key cannot be an empty string.

The tag key can be up to 64 characters in length, and cannot contain http:// or https://. The tag key cannot start with aliyun or acs:.

test

Value

string

No

The value of tag N. Valid values of N: 1 to 20. The tag value can be an empty string. The tag value can be up to 128 characters in length, and cannot contain http:// or https://. The tag value cannot start with aliyun or acs:.

1

Response elements

Element

Type

Description

Example

object

MasterSlaveServerGroupId

string

The ID of the active/standby server group.

rsp-bp19au4******

RequestId

string

The request ID.

7CA4DB76-4D32-523B-822E-5C9******

MasterSlaveBackendServers

object

MasterSlaveBackendServer

array<object>

The backend servers in the primary/secondary server group.

object

Type

string

The type of backend server. Valid values:

  • ecs: ECS instance

  • eni: ENI

  • eci: elastic container instance

ecs

Weight

integer

The weight of the backend server.

100

Description

string

The description of the primary/secondary server group.

test-112

Port

integer

The port that is used by the backend server.

82

ServerId

string

The ID of the backend server that you want to add.

i-bp1fq61enf4loa5i****

ServerType

string

The type of backend server.

Valid values: Master and Slave.

Master

Examples

Success response

JSON format

{
  "MasterSlaveServerGroupId": "rsp-bp19au4******",
  "RequestId": "7CA4DB76-4D32-523B-822E-5C9******",
  "MasterSlaveBackendServers": {
    "MasterSlaveBackendServer": [
      {
        "Type": "ecs",
        "Weight": 100,
        "Description": "test-112",
        "Port": 82,
        "ServerId": "i-bp1fq61enf4loa5i****",
        "ServerType": "Master"
      }
    ]
  }
}

Error codes

HTTP status code

Error code

Error message

Description

400 BACKEND_SERVERS_NUM_MUST_BE_TWO Backend servers num must be 2.
400 Mismatched.ZoneId The zone of the server is not matched with the cloud box loadbalancer.
400 BACKEND_SERVERS_HAVE_SAME_PORT_AND_SERVERID Backend servers have same port and serverId.
400 BACKEND_SERVERS_CAN_ONLY_CONTAIN_ONE_MASTER_AND_ONE_SLAVE Backend servers can only contain one master and one slave.
400 BACKEND_SERVER_ID_CAN_NOT_EMPTY Backend server id can not empty.
400 INVALID_SERVER_TYPE Invalid server type.
400 BACKEND_SERVER_PORT_CAN_NOT_EMPTY Backend server port can not empty.
400 RealServerPortNotSupport Real server port not support.
400 OperationUnsupported.CreateMasterSlaveServerGroup This type of backend server is not allowed to attached to singleTunnel or anyTunnel lb.
400 IncorrectStatus.RSByPassToas %s.
400 OperationFailed.ActionNotSupport The loadbalancer does not support such action.
400 RsTunnelIp2VmNameConflict %s.
400 NetworkConflict %s.
400 InvalidParam.TagValue %s.
400 InvalidParam.TagKey %s.
400 SizeLimitExceeded.Tag %s.
400 MissingParam.TagKey The param MissingParam.TagKey is missing.

See Error Codes for a complete list.

Release notes

See Release Notes for a complete list.