Adding a Backend Server Group

Function

This API is used to add a backend server group. After multiple backend servers are added to a backend server group, requests are distributed among backend servers based on the load balancing algorithm configured for the backend server group and the weight set for each backend server.

Constraints

If parameter session-persistence is configured, parameter cookie_name is available only when the value of type is APP_COOKIE.

URI

POST /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
pool	Yes	Object	Specifies the backend server group. For details, see Table 3.

**Table 3** **pool** parameter description
Parameter	Mandatory	Type	Description
tenant_id	No	String	Specifies the ID of the project where the backend server group is used. The value must be the same as the value of project_id in the token. The value contains a maximum of 255 characters.
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.
protocol	Yes	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	Yes	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.
admin_state_up	No	Boolean	Specifies the administrative status of the backend server group. This parameter is reserved. The default value is true.
listener_id	No	String	Specifies the ID of the listener associated with the backend server group. Specify either listener_id or loadbalancer_id, or both of them.
loadbalancer_id	No	String	Specifies the ID of the load balancer associated with the backend server group. Specify either listener_id or loadbalancer_id, or both of them.
session_persistence	No	Object	Specifies the sticky session timeout duration in minutes. For details, see Table 4. If the value is null, the sticky session feature is disabled.

**Table 4** **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.

Response

**Table 5** Parameter description
Parameter	Type	Description
pool	Object	Specifies the backend server group. For details, see Table 6.

**Table 6** **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 7** **members** parameter description
Parameter	Type	Description
id	String	Specifies the ID of the associated backend server.

**Table 8** **listeners** parameter description
Parameter	Type	Description
id	String	Specifies the ID of the associated backend server group.

**Table 9** **loadbalancers** parameter description
Parameter	Type	Description
id	String	Specifies the ID of the associated load balancer.

**Table 10** **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

Step 1: Query the subnet ID and IP address using the server ID. device_id in the request indicates the server ID. Obtain the values of subnet_id and ip_address of the primary NIC (the port for which primary_interface is true) in the response body.

GET https://{VPCEndpoint}/v2.0/ports?device_id=f738c464-b5c2-45df-86c0-7f436620cd54

Example response

{
    "ports": [
        {
            "id": "94971c39-46f0-443a-85e8-31cb7497c78e",
            "name": "",
            "status": "ACTIVE",
            "admin_state_up": true,
            "fixed_ips": [
                {
                    "subnet_id": "33d8b01a-bbe6-41f4-bc45-78a1d284d503",
                    "ip_address": "192.168.44.11"
                }
            ],
            "mac_address": "fa:16:3e:5c:d2:57",
            "network_id": "1b76b9c2-9b7e-4ced-81bd-d13f7389d7c9",
            "tenant_id": "04dd36f978800fe22f9bc00bea090736",
            "project_id": "04dd36f978800fe22f9bc00bea090736",
            "device_id": "f738c464-b5c2-45df-86c0-7f436620cd54",
            "device_owner": "compute:cn-north-4a",
            "security_groups": [
                "a10dfc31-0055-4b84-b36e-1291b918125c",
                "7a233393-5be2-4dff-8360-1558dd950f6e"
            ],
            "extra_dhcp_opts": [],
            "allowed_address_pairs": [],
            "binding:vnic_type": "normal",
            "binding:vif_details": {
                "primary_interface": true
            },
            "binding:profile": {},
            "port_security_enabled": true,
            "created_at": "2019-11-12T17:17:51",
            "updated_at": "2019-11-12T17:17:51"
        }
    ]
}

Step 2: Add a backend server group with the sticky session feature disabled.

POST https://{Endpoint}/v2/601240b9c5c94059b63d484c92cfe308/elb/pools

{
    "pool": {
        "lb_algorithm":"ROUND_ROBIN",
        "loadbalancer_id": "63ad9dfe-4750-479f-9630-ada43ccc8117",
        "protocol":"HTTP"
    }
}

Example request 2: Adding a backend server group with the value of type set to APP_COOKIE

POST https://{Endpoint}/v2/145483a5107745e9b3d80f956713e6a3/elb/pools

{
  "pool": {
    "lb_algorithm": "ROUND_ROBIN",
    "loadbalancer_id": "370fb112-e920-486a-b051-1d0d30704dd3",
    "protocol": "HTTP",
    "session_persistence": {
      "cookie_name": "my_cookie",
      "type": "APP_COOKIE",
      "persistence_timeout": 1
    },
    "admin_state_up": true
  }
}

Example request 3: Adding an HTTP backend server group with the value of type set to HTTP_COOKIE

POST https://{Endpoint}/v2/601240b9c5c94059b63d484c92cfe308/elb/pools 

{
    "pool": {
        "lb_algorithm":"ROUND_ROBIN",
        "loadbalancer_id": "63ad9dfe-4750-479f-9630-ada43ccc8117",
        "protocol":"HTTP",
        "session_persistence":{
        	"type":"HTTP_COOKIE"
        }
    }
}

Example Response

Example response 1

{
    "pool": {
        "lb_algorithm": "ROUND_ROBIN",
        "protocol": "HTTP",
        "description": "",
        "admin_state_up": true,
        "loadbalancers": [
            {
                "id": "63ad9dfe-4750-479f-9630-ada43ccc8117"
            }
        ],
        "tenant_id": "601240b9c5c94059b63d484c92cfe308",
        "session_persistence": null,
        "healthmonitor_id": null,
        "listeners": [],
        "members": [],
        "id": "4e496951-befb-47bf-9573-c1cd11825c07",
        "name": ""
    }
}

Example response 2

{
  "pool": {
    "lb_algorithm": "ROUND_ROBIN",
    "protocol": "HTTP",
    "description": "",
    "admin_state_up": true,
    "loadbalancers": [
      {
        "id": "6b041b9e-976b-40ba-b075-375be6110b53"
      }
    ],
    "tenant_id": "145483a5107745e9b3d80f956713e6a3",
    "session_persistence": {
      "cookie_name": "my_cookie",
      "type": "APP_COOKIE",
      "persistence_timeout": 1
    },
    "healthmonitor_id": null,
    "listeners": [
      {
        "id": "370fb112-e920-486a-b051-1d0d30704dd3"
      }
    ],
    "members": [],
    "id": "307f8968-9474-4d0c-8434-66be09dabcc1",
    "name": ""
  }
}

Example response 3

{
    "pool": {
        "lb_algorithm": "ROUND_ROBIN",
        "protocol": "HTTP",
        "description": "",
        "admin_state_up": true,
        "loadbalancers": [
            {
                "id": "63ad9dfe-4750-479f-9630-ada43ccc8117"
            }
        ],
        "tenant_id": "601240b9c5c94059b63d484c92cfe308",
        "session_persistence": {
            "persistence_timeout": 1440,
            "cookie_name": null,
            "type": "HTTP_COOKIE"
        },
        "healthmonitor_id": null,
        "listeners": [],
        "members": [],
        "id": "d46eab56-d76b-4cd3-8952-3c3c4cf113aa",
        "name": ""
    }
}