Updating a Backend Server Group

Function

This API is used to update a backend server group.

Constraints

The backend server group can be updated only when the provisioning status of the associated load balancer is ACTIVE.

URI

PUT /v3/{project_id}/elb/pools/{pool_id}

Table 1 Path parameters

Parameter

Mandatory

Type

Description

pool_id

Yes

String

Specifies the backend server group ID.

project_id

Yes

String

Specifies the project ID.

Request Parameters

Table 2 Request body parameters

Parameter

Mandatory

Type

Description

pool

Yes

UpdatePoolOption object

Specifies the backend server group.

Table 3 UpdatePoolOption

Parameter

Mandatory

Type

Description

admin_state_up

No

Boolean

Specifies the administrative status of the backend server group. The value can only be updated to true.

This parameter is unsupported. Please do not use it.

description

No

String

Provides supplementary information about the backend server group.

Minimum: 0

Maximum: 255

lb_algorithm

No

String

Specifies the load balancing algorithm used by the load balancer to route requests to backend servers.

The value can be one of the following:

  • ROUND_ROBIN: weighted round robin

  • LEAST_CONNECTIONS: weighted least connections

  • SOURCE_IP: source IP hash

When the value is SOURCE_IP, the weights of backend servers are invalid.

name

No

String

Specifies the backend server group name.

Minimum: 0

Maximum: 255

session_persistence

No

UpdatePoolSessionPersistenceOption object

Specifies whether to enable sticky sessions.

slow_start

No

UpdatePoolSlowStartOption object

Specifies whether to enable slow start. After you enable slow start, new backend servers added to the backend server group are warmed up, and the number of requests they can receive increases linearly during the configured slow start duration.

This parameter can be used when the protocol of the backend server group is HTTP or HTTPS. An error will be returned if the protocol is not HTTP or HTTPS.

This parameter is unsupported. Please do not use it.

Table 4 UpdatePoolSessionPersistenceOption

Parameter

Mandatory

Type

Description

cookie_name

No

String

Specifies the cookie name. This parameter is unsupported. Please do not use it.

Minimum: 0

Maximum: 1024

type

Yes

String

Specifies the sticky session type. The value can be SOURCE_IP, HTTP_COOKIE, or APP_COOKIE.

  • If the protocol of the backend server group is TCP or UDP, only SOURCE_IP takes effect. If the value is not SOURCE_IP, sticky sessions will not take effect.

  • If the protocol of the backend server group is HTTP or HTTPS, the value can only be HTTP_COOKIE.

APP_COOKIE is unsupported. Please do not use it.

persistence_timeout

No

Integer

Specifies the stickiness duration, in minutes.

  • If the protocol of the backend server group is TCP or UDP, the value ranges from 1 to 60, and the default value is 1.

  • If the protocol of the backend server group is HTTP or HTTPS, the value ranges from 1 to 1440, and the default value is 1440.

Table 5 UpdatePoolSlowStartOption

Parameter

Mandatory

Type

Description

enable

Yes

Boolean

Specifies whether slow start is enabled.

true indicates that slow start is enabled, and false indicates slow start is disabled.

Default: false

duration

Yes

Integer

Specifies the slow start duration, in seconds.

The value ranges from 30 to 1200, and the default value is 30.

Minimum: 30

Maximum: 1200

Default: 30

Response Parameters

Status code: 200

Table 6 Response body parameters

Parameter

Type

Description

request_id

String

Specifies the request ID. The value is automatically generated.

pool

Pool object

Specifies the backend server group.

Table 7 Pool

Parameter

Type

Description

admin_state_up

Boolean

Specifies the administrative status of the backend server group. The value can only be updated to true.

This parameter is unsupported. Please do not use it.

Default: true

description

String

Provides supplementary information about the backend server group.

healthmonitor_id

String

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

id

String

Specifies the backend server group ID.

lb_algorithm

String

Specifies the load balancing algorithm used by the load balancer to route requests to backend servers in the backend server group.

The value can be ROUND_ROBIN (weighted round robin), LEAST_CONNECTIONS (weighted least connections), or SOURCE_IP (source IP hash).

When the value is SOURCE_IP, the weight parameter is invalid.

listeners

Array of ListenerRef objects

Lists the listeners associated with the backend server group.

loadbalancers

Array of LoadBalancerRef objects

Lists the IDs of load balancers associated with the backend server group.

If only listener_id is specified during the creation of the backend server group, the ID of the loadbalancers parameter in the response is the ID of the load balancer to which the listener is added.

members

Array of MemberRef objects

Lists the backend servers in the backend server group.

name

String

Specifies the backend server group name.

project_id

String

Specifies the project ID.

protocol

String

Specifies the protocol used by the backend server group to receive requests. The protocol can be TCP, UDP, or HTTP.

  • For UDP listeners, the protocol of the backend server group must be UDP.

  • For TCP listeners, the protocol of the backend server group must be TCP.

  • For HTTP or HTTPS listeners, the protocol of the backend server group must be HTTP.

session_persistence

SessionPersistence object

Specifies the sticky session.

ip_version

String

Specifies the IP version supported by the backend server group.

The value can be dualstack, v4, or v6. When the protocol of the backend server group is TCP or UDP, ip_version is set to dualstack, indicating that both IPv4 and IPv6 are supported. When the protocol of the backend server group is HTTP, ip_version is set to v4.

Default: dualstack

slow_start

SlowStart object

Specifies whether to enable slow start. After you enable slow start, new backend servers added to the backend server group are warmed up, and the number of requests they can receive increases linearly during the configured slow start duration.

This parameter can be used when the protocol of the backend server group is HTTP or HTTPS. An error will be returned if the protocol is not HTTP or HTTPS.

This parameter is unsupported. Please do not use it.

Table 8 ListenerRef

Parameter

Type

Description

id

String

Specifies the listener ID.

Table 9 LoadBalancerRef

Parameter

Type

Description

id

String

Specifies the load balancer ID.

Table 10 MemberRef

Parameter

Type

Description

id

String

Specifies the backend server ID.

Table 11 SessionPersistence

Parameter

Type

Description

cookie_name

String

Specifies the cookie name.

This parameter is unsupported. Please do not use it.

Minimum: 0

Maximum: 1024

type

String

Specifies the sticky session type. The value can be SOURCE_IP, HTTP_COOKIE, or APP_COOKIE.

  • If the protocol of the backend server group is TCP or UDP, only SOURCE_IP takes effect. If the value is not SOURCE_IP, sticky sessions will not take effect.

  • If the protocol of the backend server group is HTTP or HTTPS, the value can only be HTTP_COOKIE.

APP_COOKIE is unsupported. Please do not use it.

persistence_timeout

Integer

Specifies the stickiness duration, in minutes.

  • If the protocol of the backend server group is TCP or UDP, the value ranges from 1 to 60, and the default value is 1.

  • If the protocol of the backend server group is HTTP or HTTPS, the value ranges from 1 to 1440, and the default value is 1440.

Table 12 SlowStart

Parameter

Type

Description

enable

Boolean

Specifies whether to enable slow start.

true indicates that this function is enabled, and false indicates this function is disabled.

Default: false

duration

Integer

Specifies the slow start duration, in seconds.

The value ranges from 30 to 1200, and the default value is 30.

Minimum: 30

Maximum: 1200

Default: 30

Example Requests

PUT

https://{elb_endpoint}/v3/99a3fff0d03c428eac3678da6a7d0f24/elb/pools/36ce7086-a496-4666-9064-5ba0e6840c75

{
  "pool" : {
    "name" : "My pool.",
    "description" : "My pool update",
    "lb_algorithm" : "LEAST_CONNECTIONS"
  }
}

Example Responses

Status code: 200

Successful request.

{
  "pool" : {
    "lb_algorithm" : "LEAST_CONNECTIONS",
    "protocol" : "TCP",
    "description" : "My pool update",
    "admin_state_up" : true,
    "loadbalancers" : [ {
      "id" : "098b2f68-af1c-41a9-8efd-69958722af62"
    } ],
    "project_id" : "99a3fff0d03c428eac3678da6a7d0f24",
    "session_persistence" : null,
    "healthmonitor_id" : null,
    "listeners" : [ {
      "id" : "0b11747a-b139-492f-9692-2df0b1c87193"
    }, {
      "id" : "61942790-2367-482a-8b0e-93840ea2a1c6"
    }, {
      "id" : "fd8f954c-f0f8-4d39-bb1d-41637cd6b1be"
    } ],
    "members" : [ ],
    "id" : "36ce7086-a496-4666-9064-5ba0e6840c75",
    "name" : "My pool.",
    "ip_version" : "dualstack"
  },
  "request_id" : "8f40128b-c72b-4b64-986a-f7e2c633d75f"
}

Status Codes

Status Code

Description

200

Successful request.

Error Codes

See Error Codes.