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    ENS:DescribeLoadBalancerTCPListenerAttribute

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    ENS:DescribeLoadBalancerTCPListenerAttribute

    Last Updated:May 07, 2026

    Call the DescribeLoadBalancerTCPListenerAttribute operation to query the configuration of a TCP listener.

    Operation description

    • API call rate: 100 calls per second.

    • Per-user call rate: 10 calls per second.

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    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

    ens:DescribeLoadBalancerTCPListenerAttribute

    get

    *All Resource

    *

    		 None None

    Request parameters

    Parameter

    Type

    Required

    Description

    Example
    ListenerPort

    integer

    Yes

    The listener port. Valid values: 1 to 65535.

    80
    LoadBalancerId

    string

    Yes

    The ID of the load balancer instance.

    lb-5snthcyu1x10g7tywj7iu****

    Response elements

    Element

    Type

    Description

    Example

    object

    The response schema.

    RequestId

    string

    The request ID.

    473469C7-AA6F-4DC5-B3DB-A3DC0DE3C83E
    ListenerPort

    integer

    The frontend port used by the load balancer instance.

    80
    Status

    string

    The status of the listener. Valid values:

    • Running: The listener is running.

    • Stopped: The listener is stopped.

    • Starting: The listener is being started.

    • Configuring: The listener is being configured.

    • Stopping: The listener is being stopped.

    Stopped
    Bandwidth

    integer

    The peak bandwidth of the load balancer. The default value is -1, which indicates unlimited bandwidth.

    -1
    Scheduler

    string

    The scheduling algorithm. Valid values:

    • wrr: Weighted Round Robin. Backend servers with higher weights receive more requests.

    • wlc: Weighted Least Connections. In addition to weights, the system considers the number of active connections to each backend server. If multiple backend servers have the same weight, the system selects the backend server with the fewest active connections.

    • rr: Round Robin. The system distributes requests sequentially to the backend servers.

    • sch: Source IP Hash. The system routes requests from the same source IP address to the same backend server.

    • tch: 4-Tuple Hash. The system routes requests that share the same 4-tuple (source IP address, destination IP address, source port, and destination port) to the same backend server.

    wrr
    PersistenceTimeout

    integer

    The session persistence timeout.

    • Default value: 0. A value of 0 indicates that session persistence is disabled.

    • Valid values: 0 to 3600.

    • Unit: seconds.

    0
    EstablishedTimeout

    integer

    The connection timeout. Valid values: 10 to 900. Unit: seconds.

    500
    HealthCheck

    string

    Specifies whether to enable health checks. Valid values:

    • on: enable

    • off: disable

    on
    HealthyThreshold

    integer

    The number of consecutive successful health checks required to change the health status of a backend server from fail (unhealthy) to success (healthy). Valid values: 2 to 10.

    Note

    This parameter takes effect only when the HealthCheck parameter is set to on.

    4
    UnhealthyThreshold

    integer

    The number of consecutive failed health checks required to change the health status of a backend server from success (healthy) to fail (unhealthy). Valid values: 2 to 10.

    Note

    This parameter takes effect only when the HealthCheck parameter is set to on.

    4
    HealthCheckConnectTimeout

    integer

    The response timeout for a health check. If a backend ENS instance does not respond within this timeout period, the health check fails.

    • Default value: 5.

    • Valid values: 1 to 300.

    • Unit: seconds.

    Note

    • This parameter takes effect only when the HealthCheck parameter is set to on.

    • If this value is less than the HealthCheckInterval value, the HealthCheckInterval value is used as the timeout period instead.

    100
    HealthCheckInterval

    integer

    The interval between health checks. Valid values: 1 to 50. Unit: seconds.

    5
    Description

    string

    The description of the listener.

    example
    HealthCheckHttpCode

    string

    The HTTP status codes that indicate a successful health check. Valid values:

    • http_2xx (Default)

    • http_3xx

    • http_4xx

    • http_5xx

    Note

    This parameter takes effect only when the HealthCheck parameter is set to on.

    http_2xx
    HealthCheckDomain

    string

    The domain name used for health checks.

    Note

    This parameter takes effect only when the HealthCheck parameter is set to on.

    example.com
    HealthCheckURI

    string

    The URI used for health checks. Length: 1 to 80 characters.

    Note

    • The URI must start with / but cannot consist solely of /.

    • This parameter takes effect only when the HealthCheck parameter is set to on.

    /example/index.html
    HealthCheckType

    string

    The health check type. Valid values:

    • tcp (Default)

    • http

    tcp
    BackendServerPort

    integer

    The port used by the backend servers. Valid values: 1 to 65535.

    8080
    HealthCheckConnectPort

    integer

    The port used for health checks. Valid values: 1 to 65535. If this parameter is not specified, the value of BackendServerPort is used.

    Note

    This parameter takes effect only when the HealthCheck parameter is set to on.

    8000
    EipTransmit

    string

    Specifies whether EIP passthrough is enabled. Valid values:

    • on: enable

    • off (Default): disable

    on

    Examples

    Success response

    JSON format

    {
  "RequestId": "473469C7-AA6F-4DC5-B3DB-A3DC0DE3C83E",
  "ListenerPort": 80,
  "Status": "Stopped",
  "Bandwidth": -1,
  "Scheduler": "wrr",
  "PersistenceTimeout": 0,
  "EstablishedTimeout": 500,
  "HealthCheck": "on",
  "HealthyThreshold": 4,
  "UnhealthyThreshold": 4,
  "HealthCheckConnectTimeout": 100,
  "HealthCheckInterval": 5,
  "Description": "example",
  "HealthCheckHttpCode": "http_2xx",
  "HealthCheckDomain": "example.com",
  "HealthCheckURI": "/example/index.html",
  "HealthCheckType": "tcp",
  "BackendServerPort": 8080,
  "HealthCheckConnectPort": 8000,
  "EipTransmit": "on"
}

    Error codes

    HTTP status code

    Error code

    Error message

    Description
    400 ens.interface.error An error occurred while call the API.
    400 LoadBalancerNotFound The input parameter loadBalancerId that is not found.
    400 ListenerNotFound Listener is not found. Listener does not exist
    400 NoPermission Permission denied.
    400 InvalidParameter.%s The specified field %s invalid. Please check it again.

    See Error Codes for a complete list.

    Release notes

    See Release Notes for a complete list.