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    Auto Scaling:DescribeCandidateInstanceType

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    Auto Scaling:DescribeCandidateInstanceType

    Last Updated:May 21, 2026

    Lists candidate instance types.

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    RAM authorization

    No authorization for this operation. If you encounter issues with this operation, contact technical support.

    Request syntax

    GET  HTTP/1.1

    Request parameters

    Parameter

    Type

    Required

    Description

    Example
    RegionId

    string

    No

    The ID of the region where the scaling group is located.

    cn-qingdao
    InstanceTypes

    array

    No

    The specified ECS instance types.

    string

    No

    An ECS instance type.

    ecs.g6.large
    ZoneIds

    array

    No

    The specified availability zones.

    string

    No

    The ID of an availability zone.

    cn-hangzhou-b
    AllowDifferentGeneration

    boolean

    No

    Specifies whether to include instance types from other generations as candidates.

    • For example, if the current instance type is ecs.c7.large, you can set this parameter to true to include instance types such as ecs.c6.large and ecs.c8.large in the list of candidates.

    true
    AllowCrossAz

    boolean

    No

    Specifies whether to include vSwitches from other availability zones as candidates.

    Note

    The instance types remain unchanged. Only new availability zones are added as candidates. If a scaling group fails to scale out in all selected availability zones due to issues such as insufficient inventory, Auto Scaling automatically adds a vSwitch in a new availability zone to the scaling group based on this setting. For example, if a scaling group is configured for the cn-hangzhou-h and cn-hangzhou-g availability zones and a scale-out fails in both zones, Auto Scaling may create a vSwitch in the cn-hangzhou-k availability zone and add it to the scaling group based on real-time inventory.

    true
    MaxPrice

    number

    No

    The maximum price for a candidate instance type.

    2
    SpotStrategy

    string

    No

    The bidding strategy for pay-as-you-go instances. Valid values:

    • NoSpot: a standard pay-as-you-go instance.

    • SpotWithPriceLimit: a spot instance with a user-defined maximum price.

    • SpotAsPriceGo: a spot instance where the system automatically bids at the market price.

    Default value: NoSpot.

    NoSpot
    SystemDiskCategories

    array

    No

    The system disk categories, ordered by priority from high to low. If Auto Scaling cannot create a system disk by using a higher-priority category, it tries the next one in the list.

    string

    No

    The category of the system disk. Valid values:

    • cloud: basic cloud disk.

    • cloud_efficiency: ultra cloud disk.

    • cloud_ssd: SSD cloud disk.

    • cloud_essd: ESSD.

    Note

    If you specify this parameter, you cannot specify SystemDisk.Category.

    cloud
    DataDiskCategories

    array

    No

    The data disk categories, ordered by priority from high to low. If Auto Scaling cannot create a data disk by using a higher-priority category, it tries the next one in the list.

    string

    No

    The category of the data disk. Valid values:

    • cloud: basic cloud disk.

    • cloud_efficiency: ultra cloud disk.

    • cloud_ssd: SSD cloud disk.

    • cloud_essd: ESSD.

    • ephemeral_ssd: local SSD disk.

    cloud_essd
    ImageId

    string

    No

    The ID of the image used to create instances.

    Note

    If the specified image contains both a system disk and data disks, any existing data disk information in the scaling configuration is cleared.

    centos6u5_64_20G_aliaegis****.vhd
    ImageName

    string

    No

    The name of the image. The name must be unique within a region. You cannot use this parameter to specify an image from Alibaba Cloud Marketplace.

    Note

    This parameter is an alternative to the ImageId parameter. If you specify ImageId, ImageName is ignored.

    centos6u5_64_20G_aliaegis_20140703.vhd
    ImageFamily

    string

    No

    The name of the image family. When specified, the latest image in this family is used to create instances. This parameter cannot be used with ImageId.

    Note

    If you do not specify the scaling group ID, you must specify at least one of ImageId, ImageName, and ImageFamily.

    hangzhou-daily-update
    Ipv6AddressCount

    integer

    No

    The number of IPv6 addresses.

    1

    Response elements

    Element

    Type

    Description

    Example

    object

    RequestId

    string

    The unique ID of the request.

    473469C7-AA6F-4DC5-B3DB-A3DC0DE3****
    CandidateInstanceTypes

    array

    A list of candidate ECS instance types.

    string

    An ECS instance type.

    ecs.c7a.2xlarge
    CandidateZoneIds

    array

    A list of candidate availability zones.

    string

    The ID of an availability zone.

    cn-hangzhou-k

    Examples

    Success response

    JSON format

    {
  "RequestId": "473469C7-AA6F-4DC5-B3DB-A3DC0DE3****",
  "CandidateInstanceTypes": [
    "ecs.c7a.2xlarge"
  ],
  "CandidateZoneIds": [
    "cn-hangzhou-k"
  ]
}

    Error codes

    See Error Codes for a complete list.

    Release notes

    See Release Notes for a complete list.