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# 使用 Application Auto Scaling 创建目标跟踪扩展策略 AWS CLI
<a name="create-target-tracking-policy-cli"></a>

此示例使用 AWS CLI 命令为 Amazon EC2 竞价型队列创建目标机架策略。对于不同的可扩展目标，请在 `--service-namespace` 中指定其命名空间，在 `--scalable-dimension` 中指定其可扩展维度，并在 `--resource-id` 中指定其资源 ID。

使用时 AWS CLI，请记住您的命令在 AWS 区域 配置文件中运行。如果您想要在不同的区域中运行命令，可以为配置文件更改默认区域，或者与命令一起使用 `--region` 参数。

**Topics**
+ [步骤 1：注册可扩展目标](#target-tracking-register-scalable-target)
+ [步骤 2：创建目标跟踪扩展策略](#create-target-tracking-policy)
+ [步骤 3：描述目标跟踪扩展策略](#describe-target-tracking-policy)

## 步骤 1：注册可扩展目标
<a name="target-tracking-register-scalable-target"></a>

如果您尚未注册，请注册可扩展目标。使用[register-scalable-target](https://docs.aws.amazon.com/cli/latest/reference/application-autoscaling/register-scalable-target.html)命令将目标服务中的特定资源注册为可扩展目标。以下示例使用 Application Auto Scaling 注册 Spot 实例集请求。Application Auto Scaling 可以扩展 Spot 实例集中的实例数，最少为 2 个实例，最多为 10 个实例。将每个 *user input placeholder* 替换为您自己的信息。

**Linux、macOS 或 Unix**

```
aws application-autoscaling register-scalable-target --service-namespace ec2 \
  --scalable-dimension ec2:spot-fleet-request:TargetCapacity \
  --resource-id spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE \
  --min-capacity 2 --max-capacity 10
```

**Windows**

```
aws application-autoscaling register-scalable-target --service-namespace ec2 ^
  --scalable-dimension ec2:spot-fleet-request:TargetCapacity ^
  --resource-id spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE ^
  --min-capacity 2 --max-capacity 10
```

**Output**  
如果成功，该命令会返回可扩展目标的 ARN。下面是示例输出。

```
{
    "ScalableTargetARN": "arn:aws:application-autoscaling:region:account-id:scalable-target/1234abcd56ab78cd901ef1234567890ab123"
}
```

## 步骤 2：创建目标跟踪扩展策略
<a name="create-target-tracking-policy"></a>

要创建目标跟踪扩展策略，可以使用以下示例来协助您开始。

**创建目标跟踪扩展策略**

1. 使用以下 `cat` 命令可以在您主目录的名为 `config.json` 的 JSON 文件中存储扩展策略的目标值和预定义指标规范。以下是将 CPU 平均使用率保持在 50% 的示例目标跟踪配置。

   ```
   $ cat ~/config.json
   {
     "TargetValue": 50.0,
     "PredefinedMetricSpecification": 
       {
         "PredefinedMetricType": "EC2SpotFleetRequestAverageCPUUtilization"
       }
   }
   ```

   有关更多信息，请参阅《App *licati [PredefinedMetricSpecification](https://docs.aws.amazon.com/autoscaling/application/APIReference/API_PredefinedMetricSpecification.html)on Auto Scaling API 参考*》中的。

   或者，您可以通过创建自定义指标规范并为 CloudWatch 的每个参数添加值来使用自定义指标进行扩展。以下是一个示例目标跟踪配置，它将指定指标的平均利用率保持在 100。

   ```
   $ cat ~/config.json
   {
      "TargetValue": 100.0,
      "CustomizedMetricSpecification":{
         "MetricName": "MyUtilizationMetric",
         "Namespace": "MyNamespace",
         "Dimensions": [
            {
               "Name": "MyOptionalMetricDimensionName",
               "Value": "MyOptionalMetricDimensionValue"
            }
         ],
         "Statistic": "Average",
         "Unit": "Percent"
      }
   }
   ```

   有关更多信息，请参阅《App *licati [CustomizedMetricSpecification](https://docs.aws.amazon.com/autoscaling/application/APIReference/API_CustomizedMetricSpecification.html)on Auto Scaling API 参考*》中的。

1. 使用以下 [put-scaling-policy](https://docs.aws.amazon.com/cli/latest/reference/application-autoscaling/put-scaling-policy.html) 命令以及您创建的 `config.json` 文件，创建一个名为 `cpu50-target-tracking-scaling-policy` 的扩展策略。

   **Linux、macOS 或 Unix**

   ```
   aws application-autoscaling put-scaling-policy --service-namespace ec2 \
     --scalable-dimension ec2:spot-fleet-request:TargetCapacity \
     --resource-id spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE \
     --policy-name cpu50-target-tracking-scaling-policy --policy-type TargetTrackingScaling \
     --target-tracking-scaling-policy-configuration file://config.json
   ```

   **Windows**

   ```
   aws application-autoscaling put-scaling-policy --service-namespace ec2 ^
     --scalable-dimension ec2:spot-fleet-request:TargetCapacity ^
     --resource-id spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE ^
     --policy-name cpu50-target-tracking-scaling-policy --policy-type TargetTrackingScaling ^
     --target-tracking-scaling-policy-configuration file://config.json
   ```

**Output**  
如果成功，此命令将返回代表您创建的两个 CloudWatch 警报的 ARNs 和名称。下面是示例输出。

   ```
   {
       "PolicyARN": "arn:aws:autoscaling:region:account-id:scalingPolicy:policy-id:resource/ec2/spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE:policyName/cpu50-target-tracking-scaling-policy",
       "Alarms": [
           {
               "AlarmARN": "arn:aws:cloudwatch:region:account-id:alarm:TargetTracking-spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE-AlarmHigh-d4f0770c-b46e-434a-a60f-3b36d653feca",
               "AlarmName": "TargetTracking-spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE-AlarmHigh-d4f0770c-b46e-434a-a60f-3b36d653feca"
           },
           {
               "AlarmARN": "arn:aws:cloudwatch:region:account-id:alarm:TargetTracking-spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE-AlarmLow-1b437334-d19b-4a63-a812-6c67aaf2910d",
               "AlarmName": "TargetTracking-spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE-AlarmLow-1b437334-d19b-4a63-a812-6c67aaf2910d"
           }
       ]
   }
   ```

## 步骤 3：描述目标跟踪扩展策略
<a name="describe-target-tracking-policy"></a>

您可使用以下 [describe-scaling-policies](https://docs.aws.amazon.com/cli/latest/reference/application-autoscaling/describe-scaling-policies.html) 命令描述指定服务命名空间的所有扩展策略。

```
aws application-autoscaling describe-scaling-policies --service-namespace ec2
```

您可使用 `--query` 参数筛选结果以仅显示目标跟踪扩展策略。有关 `query` 的语法的更多信息，请参阅 *AWS Command Line Interface 用户指南*中的[控制 AWS CLI的命令输出](https://docs.aws.amazon.com/cli/latest/userguide/cli-usage-output.html)。

**Linux、macOS 或 Unix**

```
aws application-autoscaling describe-scaling-policies --service-namespace ec2 \
  --query 'ScalingPolicies[?PolicyType==`TargetTrackingScaling`]'
```

**Windows**

```
aws application-autoscaling describe-scaling-policies --service-namespace ec2 ^
  --query "ScalingPolicies[?PolicyType==`TargetTrackingScaling`]"
```

**Output**  
下面是示例输出。

```
[
    {
        "PolicyARN": "PolicyARN",
        "TargetTrackingScalingPolicyConfiguration": {
            "PredefinedMetricSpecification": {
                "PredefinedMetricType": "EC2SpotFleetRequestAverageCPUUtilization"
            },
            "TargetValue": 50.0
        },
        "PolicyName": "cpu50-target-tracking-scaling-policy",
        "ScalableDimension": "ec2:spot-fleet-request:TargetCapacity",
        "ServiceNamespace": "ec2",
        "PolicyType": "TargetTrackingScaling",
        "ResourceId": "spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE",
        "Alarms": [
            {
                "AlarmARN": "arn:aws:cloudwatch:region:account-id:alarm:TargetTracking-spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE-AlarmHigh-d4f0770c-b46e-434a-a60f-3b36d653feca",
                "AlarmName": "TargetTracking-spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE-AlarmHigh-d4f0770c-b46e-434a-a60f-3b36d653feca"
            },
            {
                "AlarmARN": "arn:aws:cloudwatch:region:account-id:alarm:TargetTracking-spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE-AlarmLow-1b437334-d19b-4a63-a812-6c67aaf2910d",
                "AlarmName": "TargetTracking-spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE-AlarmLow-1b437334-d19b-4a63-a812-6c67aaf2910d"
            }
        ],
        "CreationTime": 1515021724.807
    }
]
```