Automate vServer Group Backend Server Replacement via API - Classic Load Balancer

Replaces backend servers in a vServer group.

Operation description

This operation can be used only to replace backend servers in a vServer group. To modify the attributes of backend servers, such as weights, call the SetVServerGroupAttribute operation.

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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:ModifyVServerGroupBackendServers

update

*instance

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

*loadbalancer

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

slb:tag
slb:tag

None

Request parameters

Parameter	Type	Required	Description	Example
RegionId	string	Yes	The ID of the region where the Classic Load Balancer (CLB) instance is deployed.	cn-hangzhou
VServerGroupId	string	Yes	The ID of the vServer group.	rsp-cige6j****
OldBackendServers	string	No	The backend servers that you want to replace. 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 SLB instances. ServerIp: the IP address of the ENI or elastic container instance. Port: the backend port. Examples: Add an ECS instance: `[{ "ServerId": "i-xxxxxxxxx", "Weight": "100", "Type": "ecs", "Port":"80","Description":"test-112" }]` Add an ENI: `[{ "ServerId": "eni-xxxxxxxxx", "Weight": "100", "Type": "eni", "ServerIp": "192.168..", "Port":"80","Description":"test-112" }]` Add an 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" }]` Add an elastic container instance `[{ "ServerId": "eci-xxxxxxxxx", "Weight": "100", "Type": "eci", "ServerIp": "192.168..", "Port":"80","Description":"test-114" }]` Note You can add only running backend servers to SLB instances. You can specify at most 20 backend servers in each call.	[{ "ServerId": "i-xxxxxxxxx", "Weight": "100", "Type": "ecs", "Port":"80","Description":"test-112" }]
NewBackendServers	string	No	The backend servers that you want to add to the vServer group. Configure the following parameters: ServerId: required. The IDs of the backend servers. Specify the IDs in a string. You can specify the IDs of ECS instances, 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 SLB instances. ServerIp: the IP address of the ENI or elastic container instance. Port: the backend port. Examples: Add an ECS instance: `[{ "ServerId": "i-xxxxxxxxx", "Weight": "100", "Type": "ecs", "Port":"80","Description":"test-112" }]` Add an ENI: `[{ "ServerId": "eni-xxxxxxxxx", "Weight": "100", "Type": "eni", "ServerIp": "192.168..", "Port":"80","Description":"test-112" }]` Add an 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" }]` Add an elastic container instance `[{ "ServerId": "eci-xxxxxxxxx", "Weight": "100", "Type": "eci", "ServerIp": "192.168..", "Port":"80","Description":"test-114" }]` Note You can add only running backend servers to SLB instances. You can specify at most 20 backend servers in each call.	[{ "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
VServerGroupId	string	The ID of the vServer group.	rsp-cige6j****
RequestId	string	The request ID.	9DEC9C28-AB05-4DDF-9A78-6B08******
BackendServers	object
BackendServer	array<object>	The backend servers.
	object
Type	string	The type of backend server. Valid values: ecs (default): ECS instance eni: ENI eci: elastic container instance	ecs
Weight	integer	The weight of the backend server.	100
Description	string	The description of the backend server.	The description of the backend server.
Port	integer	The port that is used by the backend server.	70
ServerId	string	The ID of the ECS instance or ENI.	i-bp1ge5hrp****

Examples

Success response

JSON format

{
  "VServerGroupId": "rsp-cige6j****",
  "RequestId": "9DEC9C28-AB05-4DDF-9A78-6B08******",
  "BackendServers": {
    "BackendServer": [
      {
        "Type": "ecs",
        "Weight": 100,
        "Description": "The description of the backend server.",
        "Port": 70,
        "ServerId": "i-bp1ge5hrp****"
      }
    ]
  }
}

Error codes

HTTP status code	Error code	Error message	Description
400	InvalidParameter	The specified BackendServers contain duplicated value of ServerID and Port.	The specified backend servers contain duplicate service IDs and ports.
400	Mismatched.ZoneId	The zone of the server is not matched with the cloud box loadbalancer.
400	InvalidBackendServers.ServerIpConflict	%s.
400	OperationUnsupported.ModifyVServerGroupBackendServers	This type of backend server is not allowed to attached to singleTunnel or anyTunnel lb.
400	IncorrectStatus.RSByPassToas	%s.
400	BackendServer.InvalidType	The specified Type is invalid.
400	BackendServer.ServerRegionIdNotEqual	The specified ServerRegionId must be equal.
400	OperationFailed.InvalidCen	The cen related with this loadbalancer is invalid.
400	IncorrectStatus.CenNotAssociated	The action is invalid because the loadbalancer is not associated with cen.
400	InvalidBackendServers.MissingCenBandWidth	The bandwidth is missing between loadbalancer and backendServers in cen.
400	InvalidBackendServers.VpcNotInCen	The BackendServers is not in the cen associated with the loadbalancer.
400	InvalidServerId.NotExist	The specified ServerId is not exist.
400	MissingParameter.ServerRegionId	The parameter ServerRegionId is required.
400	MissingParameter.VbrId	The parameter VbrId is required.
400	InvalidParameter.ServerRegionId	The parameter ServerRegionId is invalid for crossborder.
400	InvalidVbrId.NotInCen	The VbrId is not in the cen associated with the loadbalancer.
400	InvalidParameter.ZoneNotSupport	The zone does not support the parameter %s.
400	MasterSlaveServerConflict	The servers are conflict for MasterSlaveGroup.
400	NetworkConflict	%s.

See Error Codes for a complete list.

Release notes

See Release Notes for a complete list.