Updated on 2022-01-25 GMT+08:00

Querying Backend Server Groups

Function

This API is used to query the backend server groups and display them in a list. Filter query and pagination query are supported. Unless otherwise specified, exact match is applied.

URI

GET /v2/{project_id}/elb/pools

Table 1 Parameter description

Parameter

Mandatory

Type

Description

project_id

Yes

String

Specifies the project ID.

Request

Table 2 Parameter description

Parameter

Mandatory

Type

Description

marker

No

String

Specifies the ID of the backend server group from which pagination query starts, that is, the ID of the last backend server group on the previous page. If this parameter is not specified, the first page will be queried.

This parameter must be used together with limit.

limit

No

Integer

Specifies the number of backend server groups on each page. If this parameter is not set, all backend server groups are queried by default.

page_reverse

No

Boolean

Specifies the page direction. The value can be true or false, and the default value is false. The last page in the list requested with page_reverse set to false will not contain the "next" link, and the last page in the list requested with page_reverse set to true will not contain the "previous" link.

This parameter must be used together with limit.

id

No

String

Specifies the ID of the backend server group.

name

No

String

Specifies the name of the backend server group.

The value contains a maximum of 255 characters.

description

No

String

Provides supplementary information about the backend server group.

The value contains a maximum of 255 characters.

healthmonitor_id

No

String

Specifies the ID of the health check configured for the backend server group.

loadbalancer_id

No

String

Specifies the ID of the load balancer associated with the backend server group.

protocol

No

String

Specifies the protocol that the backend server group uses to receive requests.

TCP, UDP, and HTTP are supported.

lb_algorithm

No

String

Specifies the load balancing algorithm of the backend server group.

The value range varies depending on the protocol of the backend server group:
  • ROUND_ROBIN: indicates the weighted round robin algorithm.
  • LEAST_CONNECTIONS: indicates the weighted least connections algorithm.
  • SOURCE_IP: indicates the source IP hash algorithm.

When the value is SOURCE_IP, the weights of backend servers in the server group are invalid. For details about parameter weight, see Response.

member_address

No

String

Lists the IDs of backend servers in the backend server group.

member_device_id

No

String

Specifies the ID of the ECS corresponding to the backend server in the backend server group.

enterprise_project_id

No

String

Specifies the enterprise project ID. Enterprise projects are used for fine-grained authentication.

  • If loadbalancer_id is transmitted, the ID of the enterprise project to which the load balancer is assigned is used for authentication.
  • If loadbalancer_id is not transmitted but healthmonitor_id is transmitted, the ID of the enterprise project to which the health check is assigned is used for authentication.

Response

Table 3 Parameter description

Parameter

Type

Description

pools

Array

Specifies the backend server group. For details, see Table 4.

Table 4 pool parameter description

Parameter

Type

Description

id

String

Specifies the ID of the backend server group.

tenant_id

String

Specifies the ID of the project where the backend server group is used.

The value contains a maximum of 255 characters.

name

String

Specifies the name of the backend server group.

The value contains a maximum of 255 characters.

description

String

Provides supplementary information about the backend server group.

The value contains a maximum of 255 characters.

protocol

String

Specifies the protocol that the backend server group uses to receive requests.

TCP, UDP, and HTTP are supported.

When a backend server group is associated with a listener, the relationships between the protocol used by the listener and the protocol of the backend server group are as follows:

  • When the protocol used by the listener is UDP, the protocol of the backend server group must be UDP.
  • When the protocol used by the listener is TCP, the protocol of the backend server group must be TCP.
  • When the protocol used by the listener is HTTP or TERMINATED_HTTPS, the protocol of the backend server group must be HTTP.

lb_algorithm

String

Specifies the load balancing algorithm of the backend server group.

The value range varies depending on the protocol of the backend server group:
  • ROUND_ROBIN: indicates the weighted round robin algorithm.
  • LEAST_CONNECTIONS: indicates the weighted least connections algorithm.
  • SOURCE_IP: indicates the source IP hash algorithm. When the value is SOURCE_IP, the weights of backend servers in the server group are invalid.

members

Array

Lists the IDs of backend servers in the backend server group. For details, see Table 7.

healthmonitor_id

String

Specifies the ID of the health check configured for the backend server group.

admin_state_up

Boolean

Specifies the administrative status of the backend server group.

This parameter is reserved. The default value is true.

listeners

Array

Lists the IDs of listeners associated with the backend server group. For details, see Table 8.

loadbalancers

Array

Lists the IDs of load balancers associated with the backend server group. For details, see Table 9.

session_persistence

Object

Specifies whether to enable the sticky session feature. For details, see Table 10.

Once the sticky session feature is enabled, requests from the same client are sent to the same backend server within the specified period.

When this feature is disabled, the parameter value is null.

Table 5 members parameter description

Parameter

Type

Description

id

String

Specifies the ID of the associated backend server.

Table 6 listeners parameter description

Parameter

Type

Description

id

String

Specifies the ID of the associated backend server group.

Table 7 loadbalancers parameter description

Parameter

Type

Description

id

String

Specifies the ID of the associated load balancer.

Table 8 session_persistence parameter description

Parameter

Mandatory

Type

Description

type

Yes

String

Specifies the sticky session type.

The value range varies depending on the protocol of the backend server group:
  • SOURCE_IP: Requests are distributed based on the client's IP address. Requests from the same IP address are sent to the same backend server.
  • HTTP_COOKIE: When the client sends a request for the first time, the load balancer automatically generates a cookie and inserts the cookie into the response message. Subsequent requests are sent to the backend server that processes the first request.
  • APP_COOKIE: When the client sends a request for the first time, the backend server that receives the request generates a cookie and inserts the cookie into the response message. Subsequent requests are sent to this backend server.

When the protocol of the backend server group is TCP, only SOURCE_IP takes effect. When the protocol of the backend server group is HTTP, only HTTP_COOKIE or APP_COOKIE takes effect.

cookie_name

No

String

Specifies the cookie name.

This parameter is mandatory when the sticky session type is APP_COOKIE.

persistence_timeout

No

Integer

Specifies the sticky session timeout duration in minutes.

This parameter is invalid when type is set to APP_COOKIE.

The value range varies depending on the protocol of the backend server group:
  • When the protocol of the backend server group is TCP or UDP, the value ranges from 1 to 60.
  • When the protocol of the backend server group is HTTP, the value ranges from 1 to 1440.

Example Request

  • Example request 1: Querying all backend server groups
    GET https://{Endpoint}/v2/1867112d054b427e808cc6096d8193a1/elb/pools
  • Example request 2: Querying backend server groups whose load balancing algorithm is SOURCE_IP
    GET https://{Endpoint}/v2/1867112d054b427e808cc6096d8193a1/elb/pools?lb_algorithm=SOURCE_IP

Example Response

  • Example response 1
    {
        "pools": [
            {
                "lb_algorithm": "SOURCE_IP",
                "protocol": "TCP",
                "description": "",
                "admin_state_up": true,
                "loadbalancers": [
                    {
                        "id": "07d28d4a-4899-40a3-a939-5d09d69019e1"
                    }
                ],
                "tenant_id": "1867112d054b427e808cc6096d8193a1",
                "session_persistence": null,
                "healthmonitor_id": null,
                "listeners": [
                    {
                        "id": "1b421c2d-7e78-4a78-9ee4-c8ccba41f15b"
                    }
                ],
                "members": [
                    {
                        "id": "88f9c079-29cb-435a-b98f-0c5c0b90c2bd"
                    },
                    {
                        "id": "2f4c9644-d5d2-4cf8-a3c0-944239a4f58c"
                    }
                ],
                "id": "3a9f50bb-f041-4eac-a117-82472d8a0007",
                "name": "my-pool"
            }
        ]
    }
  • Example response 2
    {
        "pools": [
            {
                "lb_algorithm": "SOURCE_IP",
                "protocol": "TCP",
                "description": "",
                "admin_state_up": true,
                "loadbalancers": [
                    {
                        "id": "07d28d4a-4899-40a3-a939-5d09d69019e1"
                    }
                ],
                "tenant_id": "1867112d054b427e808cc6096d8193a1",
     
                "session_persistence": null,
                "healthmonitor_id": null,
                "listeners": [
                    {
                        "id": "1b421c2d-7e78-4a78-9ee4-c8ccba41f15b"
                    }
                ],
                "members": [
                    {
                        "id": "88f9c079-29cb-435a-b98f-0c5c0b90c2bd"
                    },
                    {
                        "id": "2f4c9644-d5d2-4cf8-a3c0-944239a4f58c"
                    }
                ],
                "id": "3a9f50bb-f041-4eac-a117-82472d8a0007",
                "name": "my-pool"
            }
        ]
    }

Status Code

For details, see HTTP Status Codes of Load Balancers.