Use ReplaceServersInServerGroup to replace backend servers in a server group - Server Load Balancer - Alibaba Cloud - Server Load Balancer

Replaces backend servers in a backend server group.

Operation description

The ReplaceServersInServerGroup operation is asynchronous. After a request ID is returned, the backend server replacement task is still being processed in the background.

You can call ListServerGroups to query the status of a server group:
- If the server group is in the Configuring state, the server group is being modified.
- If the server group is in the Available state, the server group is running.
You can call ListServerGroupServers to query the status of a backend server:
- If the backend server is in the Replacing state, the server group is removing the server and adding a new server.
- If the backend server is in the Available state, the backend server 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:ReplaceServersInServerGroup

update

*ServerGroup

acs:alb:{#regionId}:{#accountId}:servergroup/{#ServerGroupId}

NetworkInterface

acs:alb:{#regionId}:{#accountId}:eni/{#NetworkInterfaceId}

Instance

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

ContainerGroup

acs:alb:{#regionId}:{#accountId}:eci/{#ContainerGroupId}

None

Request parameters

Parameter	Type	Required	Description	Example
ServerGroupId	string	Yes	The server group ID. Note Server groups of the Function Compute type do not support replacing backend servers.	sgp-5114d593o96qxy****
AddedServers	array<object>	Yes	The list of backend servers to add. You can specify up to 200 servers in a single request.
	object	No	The backend server struct.
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	Yes	The port used by the backend server group. Valid values: 1 to 65535. You can specify up to 200 servers in a single request.	80
ServerId	string	No	The backend server ID. You can specify up to 200 servers in a single request. If the server group type is Instance, set this parameter to the ID of an Ecs, Eni, or Eci resource. If the server group type is Ip, set this parameter to an IP address. Note Server groups of the Function Compute type do not support replacing backend servers. You can call ListServerGroups to query the server group type.	i-bp1f9kdprbgy9uiu****
ServerIp	string	No	The IP address. If ServerType is set to Eni, you can specify the primary private IP address or a secondary private IP address of the ENI.	192.168.1.1
ServerType	string	Yes	The backend server type. You can specify up to 200 servers in a single call. Valid values: Ecs: ECS instance. Eni: ENI network interface controller (NIC) instance. Eci: ECI elastic container. Ip: IP address. Fc: Function Compute.	Ecs
Weight	integer	No	The weight of the backend server. You can specify up to 200 servers in a single request. Valid values: 0 to 100. Default value: 100. If the weight is set to 0, no requests are forwarded to the backend server.	100
RemovedServers	array<object>	Yes	The backend servers to remove.
	object	No	The struct of the backend servers to remove.
ServerId	string	Yes	The backend server ID. You can specify up to 200 servers in a single request. If the server group type is Instance, set this parameter to the ID of an Ecs, Eni, or Eci resource. If the server group type is Ip, set this parameter to an IP address. Note Server groups of the Function Compute type do not support replacing backend servers. You can call ListServerGroups to query the server group type.	i-bp1f9kdprbgy9uiu****
ServerIp	string	No	The IP address. If ServerType is set to Eni, you can specify the primary private IP address or a secondary private IP address of the ENI.	192.168.1.12
ServerType	string	Yes	The backend server type. You can specify up to 200 servers in a single call. Valid values: Ecs: ECS instance. Eni: ENI network interface controller (NIC) instance. Eci: ECI elastic container. Ip: IP address.	ecs
Port	integer	Yes	The port used by the backend server. Valid values: 1 to 65535. You can specify up to 200 servers in a single request.	81
ClientToken	string	No	The client token that is used to ensure the idempotence of the request. Generate a parameter value from your client to ensure uniqueness across different requests. ClientToken supports only ASCII characters. Note If you do not specify this parameter, the system uses the RequestId of the API request as the ClientToken. The RequestId may differ for each API request.	593B0448-D13E-4C56-AC0D-FDF0FDE0E9A3
DryRun	boolean	No	Specifies whether to perform a dry run. Valid values: true: performs a dry run without replacing backend servers in the server group. The system checks the required parameters, request syntax, and business limitations. If the check fails, the corresponding error is returned. If the check succeeds, the error code `DryRunOperation` is returned. false (default): performs a dry run and sends the request. If the check succeeds, an `HTTP 2xx` status code is returned and the operation is performed.	true

Response elements

Element	Type	Description	Example
	object	The response struct.
JobId	string	The asynchronous task ID.	72dcd26b-f12d-4c27-b3af-18f6aed5****
RequestId	string	The request ID.	365F4154-92F6-4AE4-92F8-7FF34B540710

Examples

Success response

JSON format

{
  "JobId": "72dcd26b-f12d-4c27-b3af-18f6aed5****",
  "RequestId": "365F4154-92F6-4AE4-92F8-7FF34B540710"
}

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	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	Mismatch.ServerType	The %s is mismatched for %s and %s.
400	ResourceInConfiguring	The specified resource of %s is being configured. Please try again later.
400	ResourceQuotaExceeded.LoadBalancerServersNum	The quota of %s is exceeded for resource %s, usage %s/%s.
400	ResourceInConfiguring.BackendServer	The specified resource of %s is being configured, please try again later.	The specified resource of %s is being configured, please try again later.
400	IdempotentParameterMismatch	The request uses the same client token as a previous, but non-identical request. Do not reuse a client token with different requests, unless the requests are identical.	The request uses the same client token as a previous, but non-identical request. Do not reuse a client token with different requests, unless the requests are identical.
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.
404	ResourceNotFound.BackendServer	The specified resource %s is not found.

See Error Codes for a complete list.

Release notes

See Release Notes for a complete list.