AddBackendServers - Server Load Balancer - Alibaba Cloud Documentation Center

Adds backend servers.

Operation description

Note If multiple identical Elastic Compute Service (ECS) instances are specified in a request, only the first ECS instance is added. The other ECS instances are ignored. If the backend server that you add is the same as one of the existing backend servers that are already associated with the listener, an error message is returned.

Debugging

OpenAPI Explorer automatically calculates the signature value. For your convenience, we recommend that you call this operation in OpenAPI Explorer.

Debug

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:
- The required resource types are displayed in bold characters.
- If the permissions cannot be granted at the resource level, All Resources is 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
slb:AddBackendServers	update	LoadBalancer acs:slb:{#regionId}:{#accountId}:loadbalancer/{#LoadBalancerId} Instance acs:ecs:{#regionId}:{#accountId}:instance/{#InstanceId}	none	none

Request parameters

Parameter	Type	Required	Description	Example
RegionId	string	No	The ID of the region where the Classic Load Balancer (CLB) instance is deployed. You can call the DescribeRegions operation to query the most recent region list.	cn-beijing
LoadBalancerId	string	Yes	The ID of the CLB instance.	lb-2ze7o5h52g02kkzz******
BackendServers	string	No	The list of backend servers that you want to add. Set the following parameters: ServerId: Required. This value must be a string. Enter the ID of an ECS instance, elastic network interface (ENI), or elastic container instance. If ServerId is set to the ID of an ENI or elastic container instance, Type is required. Weight: the weight of the backend server. Valid values: 0 to 100. Default value: 100. If the value is set to 0, no requests are forwarded to the backend server. Description: Optional. The description of the backend server. This value must be 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): an ECS instance eni: an ENI eci: an elastic container instance Note You can specify ENIs and elastic container instances as the backend servers only for high-performance CLB instances. ServerIp: the IP address of the ECS instance, ENI, or elastic container instance Port: the backend port Examples: ECS instance: `[{ "ServerId": "i-xxxxxxxxx", "Weight": "100", "Type": "ecs", "Port":"80","Description":"test-112" }]` ENI: `[{ "ServerId": "eni-xxxxxxxxx", "Weight": "100", "Type": "eni", "ServerIp": "192.168..", "Port":"80","Description":"test-112" }]` ENI with multiple IP addresses: `[{ "ServerId": "eni-xxxxxxxxx", "Weight": "100", "Type": "eni", "ServerIp": "192.168..", "Port":"80","Description":"test-113" },{ "ServerId": "eni-xxxxxxxxx", "Weight": "100", "Type": "eni", "ServerIp": "172.166..", "Port":"80","Description":"test-113" }]` Elastic container instance: `[{ "ServerId": "eci-xxxxxxxxx", "Weight": "100", "Type": "eci", "ServerIp": "192.168..", "Port":"80","Description":"test-114" }]` Note The backend servers that you add to a CLB instance must be in the Running state. You can add at most 20 backend servers to a CLB instance in each request.	[{ "ServerId": "eni-xxxxxxxxx", "Weight": "100", "Type": "eni", "ServerIp": "192.168..", "Port":"80","Description":"test-112" },{ "ServerId": "eni-xxxxxxxxx", "Weight": "100", "Type": "eni", "ServerIp": "172.166..", "Port":"80","Description":"test-113" }]

Response parameters

Parameter	Type	Description	Example
	object
LoadBalancerId	string	The ID of the CLB instance.	lb-2ze7o5h52g02kkzz****
RequestId	string	The ID of the request.	34B82C81-F13B-4EEB-99F6-A048C67CC830
BackendServers	array<object>	The list of backend servers.
	object
Type	string	The type of the backend server. Valid values: ecs (default): an ECS instance eni: an ENI eci: an elastic container instance	ecs
Weight	string	The weight of the backend server. Valid values: 0 to 100. Default value: 100. If the value is set to 0, no requests are forwarded to the backend server.	100
Description	string	The description of the backend server.	backend server
ServerId	string	The ID of the ECS instance, ENI, or elastic container instance.	i-2zej4lxhjoq1icu*****

Examples

Sample success responses

JSONformat

{
  "LoadBalancerId": "lb-2ze7o5h52g02kkzz****",
  "RequestId": "34B82C81-F13B-4EEB-99F6-A048C67CC830",
  "BackendServers": {
    "BackendServer": [
      {
        "Type": "ecs",
        "Weight": "100",
        "Description": "backend server",
        "ServerId": "i-2zej4lxhjoq1icu*****"
      }
    ]
  }
}

Error codes

HTTP status code	Error code	Error message	Description
400	InvalidParameter	The specified load balancer does not support the network type of the ECS instance.	The specified SLB instance does not support this network type ECS instance. Switch to another network type and try again.
400	Mismatched.ZoneId	The zone of the server is not matched with the cloud box loadbalancer.	-
400	BackendServerProcessing	Backend Server is adding, please try again later.	-
400	InvalidBackendServers.ServerIpConflict	%s.	-
400	OperationUnsupported.AddBackendServers	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	NetworkConflict	%s.	-
400	SystemBusy	The system is busy.	The service is unavailable. Please try again later.

For a list of error codes, visit the Service error codes.

Change history

Change time	Summary of changes	Operation

No change history