Call AddBackendServers to add ECS ENI and ECI as backend servers - Server Load Balancer

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.

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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:AddBackendServers

update

*LoadBalancer

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

*Instance

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

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 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 elements

Element	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	object
BackendServer	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. Note If you do not specify Description in the request, this parameter is not displayed.	The description of the backend server.
ServerId	string	The ID of the ECS instance, ENI, or elastic container instance.	i-2zej4lxhjoq1icu*****

Examples

Success response

JSON format

{
  "LoadBalancerId": "lb-2ze7o5h52g02kkzz****",
  "RequestId": "34B82C81-F13B-4EEB-99F6-A048C67CC830",
  "BackendServers": {
    "BackendServer": [
      {
        "Type": "ecs",
        "Weight": "100",
        "Description": "The description of the 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.
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.	System Busy

See Error Codes for a complete list.

Release notes

See Release Notes for a complete list.