这是 AWS CDK v2 开发者指南。旧版 CDK v1 于 2022 年 6 月 1 日进入维护阶段，并于 2023 年 6 月 1 日终止支持。

本文属于机器翻译版本。若本译文内容与英语原文存在差异，则一律以英文原文为准。

# 设置 CloudWatch 警报
<a name="how-to-set-cw-alarm"></a>

使用 [https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_cloudwatch-readme.html](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_cloudwatch-readme.html) 包在 CloudWatch 指标上设置 Amazon CloudWatch 警报。您可以使用预定义的指标，也可以创建自己的指标。

## 使用现有指标
<a name="how-to-set-cw-alarm-use-metric"></a>

许多 AWS 构造库模块允许您在现有指标上设置警报，方法是将指标名称传递给具有指标的对象实例上的便捷方法。例如，给定一个 Amazon SQS 队列，您可以从队列的 [https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_sqs.Queue.html#metricmetricname-props](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_sqs.Queue.html#metricmetricname-props) 方法中获取指标 **ApproximateNumberOfMessagesVisible**：

**Example**  

```
const metric = queue.metric("ApproximateNumberOfMessagesVisible");
```

```
const metric = queue.metric("ApproximateNumberOfMessagesVisible");
```

```
metric = queue.metric("ApproximateNumberOfMessagesVisible")
```

```
Metric metric = queue.metric("ApproximateNumberOfMessagesVisible");
```

```
var metric = queue.Metric("ApproximateNumberOfMessagesVisible");
```

## 创建您自己的指标
<a name="how-to-set-cw-alarm-new-metric"></a>

按如下方式创建您自己的[指标](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_cloudwatch.Metric.html)，其中*命名空间*值应类似于 Amazon SQS 队列的** AWS/SQS**。您还需要指定指标的名称和维度：

**Example**  

```
const metric = new cloudwatch.Metric({
  namespace: 'MyNamespace',
  metricName: 'MyMetric',
  dimensionsMap: { MyDimension: 'MyDimensionValue' }
});
```

```
const metric = new cloudwatch.Metric({
  namespace: 'MyNamespace',
  metricName: 'MyMetric',
  dimensionsMap: { MyDimension: 'MyDimensionValue' }
});
```

```
metric = cloudwatch.Metric(
    namespace="MyNamespace",
    metric_name="MyMetric",
    dimensionsMap=dict(MyDimension="MyDimensionValue")
)
```

```
Metric metric = Metric.Builder.create()
        .namespace("MyNamespace")
        .metricName("MyMetric")
        .dimensionsMap(java.util.Map.of(    // Java 9 or later
            "MyDimension", "MyDimensionValue"))
        .build();
```

```
var metric = new Metric(this, "Metric", new MetricProps
{
    Namespace = "MyNamespace",
    MetricName = "MyMetric",
    Dimensions = new Dictionary<string, object>
    {
        { "MyDimension", "MyDimensionValue" }
    }
});
```

## 创建警报
<a name="how-to-set-cw-alarm-create"></a>

有了现有指标或您定义的指标后，就可以创建警报。在此示例中，当过去三个评估周期中有两个评估周期的指标超过 100 时，就会发出警报。您可以通过 `comparisonOperator` 属性在警报中使用小于等比较。大于或等于是 AWS CDK 的默认值，因此我们不需要指定。

**Example**  

```
const alarm = new cloudwatch.Alarm(this, 'Alarm', {
  metric: metric,
  threshold: 100,
  evaluationPeriods: 3,
  datapointsToAlarm: 2,
});
```

```
const alarm = new cloudwatch.Alarm(this, 'Alarm', {
  metric: metric,
  threshold: 100,
  evaluationPeriods: 3,
  datapointsToAlarm: 2
});
```

```
alarm = cloudwatch.Alarm(self, "Alarm",
    metric=metric,
    threshold=100,
    evaluation_periods=3,
    datapoints_to_alarm=2
)
```

```
import software.amazon.awscdk.services.cloudwatch.Alarm;
import software.amazon.awscdk.services.cloudwatch.Metric;

Alarm alarm = Alarm.Builder.create(this, "Alarm")
        .metric(metric)
        .threshold(100)
        .evaluationPeriods(3)
        .datapointsToAlarm(2).build();
```

```
var alarm = new Alarm(this, "Alarm", new AlarmProps
{
    Metric = metric,
    Threshold = 100,
    EvaluationPeriods = 3,
    DatapointsToAlarm = 2
});
```

创建警报的另一种方法是使用指标的 [https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_cloudwatch.Metric.html#createwbralarmscope-id-props](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_cloudwatch.Metric.html#createwbralarmscope-id-props) 方法，该方法基本上采用与 `Alarm` 构造函数相同的属性。您无需传递该指标，因为已知该指标。

**Example**  

```
metric.createAlarm(this, 'Alarm', {
  threshold: 100,
  evaluationPeriods: 3,
  datapointsToAlarm: 2,
});
```

```
metric.createAlarm(this, 'Alarm', {
  threshold: 100,
  evaluationPeriods: 3,
  datapointsToAlarm: 2,
});
```

```
metric.create_alarm(self, "Alarm",
    threshold=100,
    evaluation_periods=3,
    datapoints_to_alarm=2
)
```

```
metric.createAlarm(this, "Alarm", new CreateAlarmOptions.Builder()
        .threshold(100)
        .evaluationPeriods(3)
        .datapointsToAlarm(2)
        .build());
```

```
metric.CreateAlarm(this, "Alarm", new CreateAlarmOptions
{
    Threshold = 100,
    EvaluationPeriods = 3,
    DatapointsToAlarm = 2
});
```