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    Auto Scaling:ModifyScalingRule

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    Auto Scaling:ModifyScalingRule

    Last Updated:Sep 10, 2026

    Modifies a scaling rule.

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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

    ess:ModifyScalingRule

    update

    *ScalingGroup

    acs:ess:{#regionId}:{#accountId}:scalinggroup/{#ScalingGroupId}

    		 None None

    Request parameters

    Parameter

    Type

    Required

    Description

    Example
    ScalingRuleId

    string

    Yes

    The ID of the scaling rule that you want to modify.

    asr-bp1dvirgwkoowxk7****
    ScalingRuleName

    string

    No

    The name of the scaling rule. The name must be 2 to 64 characters in length and can contain digits, uppercase letters, lowercase letters, Chinese characters, underscores (_), hyphens (-), and periods (.). It must start with a digit, letter, or Chinese character.

    Note

    The name of a scaling rule must be unique within the same scaling group under the same Alibaba Cloud account in the same region.

    scalingrule****
    Cooldown

    integer

    No

    The cooldown time of the scaling rule. This parameter is applicable only to simple scaling rules.

    Valid values: 0 to 86400. Unit: seconds.

    60
    MinAdjustmentMagnitude

    integer

    No

    The minimum number of instances to adjust in a scaling rule. This parameter takes effect only when the scaling rule type is SimpleScalingRule or StepScalingRule and AdjustmentType is set to PercentChangeInCapacity.

    1
    AdjustmentType

    string

    No

    The adjustment method of the scaling rule. This parameter is applicable to simple scaling rules and step scaling rules, and is required in this case. Valid values:

    • QuantityChangeInCapacity: adds or removes a specified number of ECS instances.

    • PercentChangeInCapacity: adds or removes a specified percentage of ECS instances.

    • TotalCapacity: adjusts the number of ECS instances in the current scaling group to a specified value.

    QuantityChangeInCapacity
    AdjustmentValue

    integer

    No

    The adjustment value of the scaling rule. This parameter is applicable to simple scaling rules and step scaling rules, and is required in this case. The number of ECS instances adjusted in a single scaling activity cannot exceed 1,000. Valid values vary based on the adjustment method:

    • QuantityChangeInCapacity: -1000 to 1000.

    • PercentChangeInCapacity: -100 to 10000.

    • TotalCapacity: 0 to 2000.

    100
    EstimatedInstanceWarmup

    integer

    No

    The warm-up period of an instance. This parameter is applicable to target tracking scaling rules and step scaling rules. An ECS instance in the warm-up state is added to the scaling group as expected, but CloudMonitor does not report monitoring data for the instance during this period.

    Note

    When the number of ECS instances to scale is dynamically calculated, instances in the warm-up state are not counted toward the existing instance count.

    Valid values: 0 to 86400. Unit: seconds.

    60
    MetricName

    string

    No

    The predefined metric. This parameter is applicable to target tracking scaling rules and predictive scaling rules, and is required in this case.

    Valid values for target tracking scaling rules:

    • CpuUtilizationAgent: (Agent) CPU utilization (recommended).

    • MemoryUtilization: (Agent) memory utilization (recommended).

    • CpuUtilization: (ECS) average CPU utilization.

    • IntranetTx: (ECS) average outbound traffic over the internal network.

    • IntranetRx: (ECS) average inbound traffic over the internal network.

    • VpcInternetTx: (ECS) average outbound traffic over the Internet.

    • VpcInternetRx: (ECS) average inbound traffic over the Internet.

    • LoadBalancerRealServerAverageQps: (ALB) QPS per server in a server group.

    Valid values for predictive scaling rules:

    • CpuUtilization: (ECS) average CPU utilization.

    • IntranetRx: (ECS) average inbound traffic over the internal network.

    • IntranetTx: (ECS) average outbound traffic over the internal network.

    For more information, see Event-triggered tasks for system monitoring.

    CpuUtilization
    TargetValue

    number

    No

    The target value. This parameter is applicable to target tracking scaling rules and predictive scaling rules. The value of TargetValue can have up to three decimal places and must be greater than 0.

    0.125
    DisableScaleIn

    boolean

    No

    Specifies whether to disable scale-in. This parameter is applicable only to target tracking scaling rules.

    true
    ScaleInEvaluationCount

    integer

    No

    After a target tracking scaling rule is created, an event-triggered task is automatically created. This parameter specifies the number of consecutive times that the threshold condition must be met before the corresponding scale-in event-triggered task triggers an alert.

    15
    ScaleOutEvaluationCount

    integer

    No

    After a target tracking scaling rule is created, an event-triggered task is automatically created. This parameter specifies the number of consecutive times that the threshold condition must be met before the corresponding scale-out event-triggered task triggers an alert.

    3
    PredictiveScalingMode

    string

    No

    The mode of the predictive scaling rule. Valid values:

    • PredictAndScale: generates prediction results and creates prediction tasks.

    • PredictOnly: generates prediction results but does not create prediction tasks.

    PredictAndScale
    PredictiveValueBehavior

    string

    No

    The method used to handle the maximum value of the predictive scaling rule. Valid values:

    • MaxOverridePredictiveValue: the initial maximum value overrides the predicted value. If the predicted value is greater than the initial maximum value, the maximum value of the prediction task is set to the initial maximum value.

    • PredictiveValueOverrideMax: the predicted value overrides the initial maximum value. If the predicted value is greater than the initial maximum value, the maximum value of the prediction task is set to the predicted value.

    • PredictiveValueOverrideMaxWithBuffer: the predicted value is increased by a specified percentage. The predicted value is increased based on the PredictiveValueBuffer percentage. If the increased value is greater than the initial maximum value, the increased value is used.

    MaxOverridePredictiveValue
    PredictiveValueBuffer

    integer

    No

    This parameter takes effect when PredictiveValueBehavior is set to PredictiveValueOverrideMaxWithBuffer. The predicted value is increased by this percentage. If the increased value is greater than the initial maximum value, the increased value is used. Valid values: 0 to 100.

    50
    PredictiveTaskBufferTime

    integer

    No

    Prediction tasks automatically created by a predictive scaling rule execute on the hour by default. You can configure a buffer time to execute prediction tasks ahead of schedule and prepare resources in advance. Valid values: 0 to 60.

    30
    InitialMaxSize

    integer

    No

    The maximum number of instances in the scaling group. This parameter is used together with PredictiveValueBehavior.

    100
    StepAdjustment

    array<object>

    No

    The collection of step adjustment information for step scaling.

    object

    No

    The collection of step adjustment information for step scaling.

    MetricIntervalUpperBound

    number

    No

    The upper bound of a step adjustment. This parameter is applicable only to step scaling rules. Valid values: -9.999999E18 to 9.999999E18.

    5.0
    ScalingAdjustment

    integer

    No

    The number of instances to scale in a step adjustment. This parameter is applicable only to step scaling rules.

    1
    MetricIntervalLowerBound

    number

    No

    The lower bound of a step adjustment. This parameter is applicable only to step scaling rules. Valid values: -9.999999E18 to 9.999999E18.

    1.0
    AlarmDimension

    array<object>

    No

    The dimension information associated with the metric. This parameter is applicable to target tracking scaling rules. Set this parameter when the metric requires additional dimension information. For example, the LoadBalancerRealServerAverageQps metric requires the rulePool dimension information.

    object

    No

    The dimension information associated with the metric. This parameter is applicable to target tracking scaling rules. Set this parameter when the metric requires additional dimension information. For example, the LoadBalancerRealServerAverageQps metric requires the rulePool dimension information.

    DimensionKey

    string

    No

    The key of the dimension associated with the metric.

    rulePool
    DimensionValue

    string

    No

    The value of the dimension associated with the metric.

    sgp-l1cbirz451yxu2****
    MetricType

    string

    No

    The type of the metric. Valid values:

    • system: uses CloudMonitor system metrics.

    • custom: uses custom metrics reported to CloudMonitor.

    • hybrid: uses Hybrid Cloud Monitoring metrics.

    system
    HybridMonitorNamespace

    string

    No

    The ID of the Hybrid Cloud Monitoring monitoring metrics repository.

    To manage monitoring metrics repositories, see Manage monitoring metrics repositories.

    aliyun-test
    HybridMetrics

    array<object>

    No

    The Hybrid Cloud Monitoring monitoring metrics settings. For more information about how to configure this parameter, see Use formula-based custom target tracking scaling rules.

    array<object>

    No

    Id

    string

    No

    The reference ID of the metric in the formula expression.

    a
    Expression

    string

    No

    The formula expression for multiple Hybrid Cloud Monitoring metrics. The calculation result of the expression is used to trigger scaling activities.

    The expression must comply with the Reverse Polish Notation (RPN) specification, and only the + - * / operators are supported.

    (a+b)/2
    MetricName

    string

    No

    The name of the monitoring metrics in the Hybrid Cloud Monitoring monitoring metrics repository.

    AliyunSmq_NumberOfMessagesVisible
    Statistic

    string

    No

    The statistical method of the metric. Valid values:

    • Average: the average of all data points within the specified interval.

    • Minimum: the minimum value of all data points within the specified interval.

    • Maximum: the maximum value of all data points within the specified interval.

    Average
    Dimensions

    array<object>

    No

    The metric dimensions. Specifies the resources to monitor for the metric.

    object

    No

    DimensionKey

    string

    No

    The key of the metric dimension.

    queue
    DimensionValue

    string

    No

    The value of the metric dimension.

    testQueue
    AlarmOptions

    object

    No

    The alert property definitions.

    Period

    integer

    No

    The statistical period for monitoring data in the target tracking scaling rule. Unit: seconds. Valid values:

    Note

    Default value: 60.

    60

    Response elements

    Element

    Type

    Description

    Example

    object

    RequestId

    string

    The request ID.

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

    Examples

    Success response

    JSON format

    {
  "RequestId": "473469C7-AA6F-4DC5-B3DB-A3DC0DE3****"
}

    Error codes

    See Error Codes for a complete list.

    Release notes

    See Release Notes for a complete list.