Creates a scaling rule. The purpose of a scaling rule varies based on its type. You can use a scaling rule to trigger a scaling activity or adjust the boundary values for a scaling group. You can call the CreateScalingRule operation to create different types of scaling rules based on your business requirements. For example, if your business requires only automatic adjustment of the boundary values for your scaling group, you can call this operation to create a predictive scaling rule.
Operation description
A scaling rule defines the specific scaling action. For example, you can use a scaling rule to define N instances to add or remove. If the execution of a scaling rule causes the total number of Elastic Compute Service (ECS) instances or elastic container instances in the scaling group to drop below the value of MinSize or to exceed the value of MaxSize, Auto Scaling adjusts the number of instances to add or remove, which ensures that the total number of instances stays within the valid range. Take note that Auto Scaling does not adjust the number of instances that you defined in the scaling rule. Examples:
- The maximum number of instances (MaxSize) that can be contained in a scaling group is 3 and the current number of instances (Total Capacity) in the scaling group is 2. In this example, the Add3 scaling rule is created to add three ECS instances to the scaling group. However, after you execute Add3, Auto Scaling adds only one ECS instance to the scaling group. In addition, the number of ECS instances to add in the Add3 scaling rule remains unchanged.
- The minimum number of instances (MinSize) that must be contained in a scaling group is 2 and the current number of instances (Total Capacity) is 3. In this example, the Remove5 scaling rule is created to remove five ECS instances from the scaling group. However, after you execute Remove5, Auto Scaling only removes one ECS instance from the scaling group. In addition, the number of ECS instances to remove in the Remove5 scaling rule remains unchanged.
Before you call this operation, take note of the following items:
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If you set AdjustmentType to TotalCapacity, the total number of ECS instances or elastic container instances in your scaling group will be adjusted to a specified number when the scaling rule that you create by calling this operation is executed. You must set AdjustmentValue to an integer that is greater than 0.
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If you set AdjustmentType to QuantityChangeInCapacity or PercentChangeInCapacity, a positive value of AdjustmentValue specifies that a specific number of ECS instances or elastic container instances will be added to your scaling group, and a negative value of AdjustmentValue specifies that a specific number of ECS instances or elastic container instances will be removed from the scaling group.
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If you set AdjustmentType to PercentChangeInCapacity, Auto Scaling calculates the number of ECS instances or elastic container instances to add or remove by multiplying the current capacity of the scaling group (Total Capacity) by AdjustmentValue divided by 100, rounding off the result to determine the final adjustment count.
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If you specify a cooldown period for a scaling rule, the cooldown period of the scaling rule takes effect after you execute the scaling rule. If you do not specify a cooldown period for a scaling rule, the value of DefaultCooldown of the scaling group takes effect after you execute the scaling rule.
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You can create only a limited number of scaling rules for a scaling group. For more information, see Limits .
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The following API operations may use the unique identifier of a scaling rule (ScalingRuleAri) that is returned after you call the CreateScalingRule operation:
- ExecuteScalingRule: You can call this operation to manually execute a scaling rule. In this operation, you can set ScalingRuleAri to the unique identifier of the scaling rule that you want to execute.
- CreateScheduledTask: You can call this operation to create a scheduled task for a scaling rule. In this operation, you can set ScalingRuleAri to the unique identifier of the scaling rule for which you want to create a scheduled task.
Debugging
Authorization information
The following table shows the authorization information corresponding to the API. The authorization information can be used in the Action policy element to grant a RAM user or RAM role the permissions to call this API operation. Description:
- Operation: the value that you can use in the Action element to specify the operation on a resource.
- Access level: the access level of each operation. The levels are read, write, and list.
- Resource type: the type of the resource on which you can authorize the RAM user or the RAM role to perform the operation. Take note of the following items:
- The required resource types are displayed in bold characters.
- If the permissions cannot be granted at the resource level,
All Resourcesis used in the Resource type column of the operation.
- Condition Key: the condition key that is defined by the cloud service.
- Associated operation: other operations that the RAM user or the RAM role must have permissions to perform to complete the operation. To complete the operation, the RAM user or the RAM role must have the permissions to perform the associated operations.
| Operation | Access level | Resource type | Condition key | Associated operation |
|---|---|---|---|---|
| ess:CreateScalingRule | create |
|
| none |
Request parameters
| Parameter | Type | Required | Description | Example |
|---|---|---|---|---|
| ScalingGroupId | string | Yes | The ID of the scaling group to which the scaling rule belongs. | asg-bp1ffogfdauy0jw0**** |
| ScalingRuleName | string | No | The name of the scaling rule. The name must be 2 to 64 characters in length, and can contain letters, digits, underscores (_), hyphens (-), and periods (.). The name must start with a letter or a digit. The name of each scaling rule must be unique under the same account within a region. If you leave this parameter empty, the scaling rule ID is used. | scalingrule**** |
| Cooldown | integer | No | The cooldown time of the scaling rule. This parameter is available only if you set the ScalingRuleType parameter to SimpleScalingRule. Valid values: 0 to 86400. Unit: seconds. By default, this parameter is left empty. | 60 |
| MinAdjustmentMagnitude | integer | No | The minimum number of instances that must be scaled when the AdjustmentType parameter is set to PercentChangeInCapacity. This parameter takes effect only if you set the ScalingRuleType parameter to SimpleScalingRule or StepScalingRule. | 1 |
| AdjustmentType | string | No | The scaling method of the scaling rule. This parameter is required only if you set the ScalingRuleType parameter to SimpleScalingRule or StepScalingRule. Valid values:
| QuantityChangeInCapacity |
| AdjustmentValue | integer | No | The number of instances that must be scaled based on the scaling rule. This parameter is required only if you set the ScalingRuleType parameter to SimpleScalingRule or StepScalingRule. The number of ECS instances that are scaled in a single scaling activity cannot exceed 1,000.
| 100 |
| ScalingRuleType | string | No | The type of the scaling rule. Valid values:
Default value: SimpleScalingRule | SimpleScalingRule |
| EstimatedInstanceWarmup | integer | No | The warmup period of an instance. This parameter is available only if you set the ScalingRuleType parameter to TargetTrackingScalingRule or PredictiveScalingRule. Auto Scaling adds ECS instances that are in the warmup state to a scaling group but does not report monitoring data to CloudMonitor during the warmup period. Note
Auto Scaling calculates the number of ECS instances that must be scaled. ECS instances in the warmup state are not counted towards the current capacity of the scaling group.
Valid values: 0 to 86400. Unit: seconds. Default value: 300. | 300 |
| MetricName | string | No | The predefined metric that you want to monitor. If you set ScalingRuleType to TargetTrackingScalingRule or PredictiveScalingRule, you must specify this parameter. Valid values if you set ScalingRuleType to TargetTrackingScalingRule:
Valid values if you set ScalingRuleType to PredictiveScalingRule:
For more information, see Event-triggered tasks of the system monitoring type. | CpuUtilization |
| TargetValue | float | No | The target value. This parameter is required only if you set the ScalingRuleType parameter to TargetTrackingScalingRule or PredictiveScalingRule. The value must be greater than 0 and can have up to three decimal places. | 0.125 |
| DisableScaleIn | boolean | No | Specifies whether to disable scale-in. This parameter is available only if you set ScalingRuleType to TargetTrackingScalingRule. Default value: false. | false |
| ScaleInEvaluationCount | integer | No | The number of consecutive times that the event-triggered task created for scale-in activities must meet the threshold conditions before an alert is triggered. After a target tracking scaling rule is created, an event-triggered task is automatically created and then associated with the target tracking scaling rule. Default value: 15. | 15 |
| ScaleOutEvaluationCount | integer | No | The number of consecutive times that the event-triggered task created for scale-out activities must meet the threshold conditions before an alert is triggered. After a target tracking scaling rule is created, an event-triggered task is automatically created and then associated with the target tracking scaling rule. Default value: 3. | 3 |
| PredictiveScalingMode | string | No | The mode of the predictive scaling rule. Valid values:
Default value: PredictAndScale. | PredictAndScale |
| PredictiveValueBehavior | string | No | The maximum value for predication tasks. Valid values:
Default value: MaxOverridePredictiveValue. | MaxOverridePredictiveValue |
| PredictiveValueBuffer | integer | No | The ratio based on which the predicted value is increased when you set Default value: 0. | 50 |
| PredictiveTaskBufferTime | integer | No | The amount of buffer time before the prediction task is executed. By default, all prediction tasks that are automatically created for a predictive scaling rule are executed on the hour. You can specify an amount of buffer time for resource preparation before the prediction tasks are executed. Valid values: 0 to 60. Unit: minutes. Default value: 0. | 30 |
| InitialMaxSize | integer | No | The maximum number of ECS instances that can be contained in the scaling group. If you specify InitialMaxSize, you must specify The default value of this parameter is the value of MaxSize. | 100 |
| StepAdjustments | array<object> | No | Details of the step adjustments. | |
| object | No | Details of the step adjustments. | ||
| MetricIntervalUpperBound | float | No | The upper limit that is specified in a step adjustment. Valid values: -9.999999E18 to 9.999999E18. | 5.0 |
| ScalingAdjustment | integer | No | The number of ECS instances that you want to scale in a step adjustment. This parameter is available only if you set the ScalingRuleType parameter to StepScalingRule. | 1 |
| MetricIntervalLowerBound | float | No | The lower limit specified in a step adjustment. This parameter is available only if you set the ScalingRuleType parameter to StepScalingRule. Valid values: -9.999999E18 to 9.999999E18. | 1.0 |
| RegionId | string | No | The region ID of the scaling group. | cn-hangzhou |
| AlarmDimensions | array<object> | No | The metric dimensions. This parameter is applicable to target tracking scaling rules. If your predefined metric requires extra dimensions, you must specify this parameter. For example, if you use LoadBalancerRealServerAverageQps as your predefined metric, you must use this parameter to specify the rulePool dimension. | |
| object | No | |||
| DimensionKey | string | No | The dimension key of the metric. | rulePool |
| DimensionValue | string | No | The dimension value of the metric. | sgp-l1cbirz451yxuxxx |
Response parameters
Examples
Sample success responses
JSONformat
{
"ScalingRuleAri": "ari:acs:ess:cn-hangzhou:140692647406****:scalingrule/asr-bp1dvirgwkoowxk7****",
"RequestId": "473469C7-AA6F-4DC5-B3DB-A3DC0DE3****",
"ScalingRuleId": "asr-bp1dvirgwkoowxk7****"
}Error codes
For a list of error codes, visit the Service error codes.
Change history
| Change time | Summary of changes | Operation |
|---|---|---|
| 2024-09-13 | The request parameters of the API has changed | View Change Details |
| 2023-04-03 | The request parameters of the API has changed | View Change Details |