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# 使用 适用于 PHP 的 AWS SDK 版本 3 来使用 Amazon CloudWatch 警报
<a name="cw-examples-work-with-alarms"></a>

Amazon CloudWatch 警报在指定时间段内监控某个指标。它在多个时间段内根据相对于给定阈值的指标值，执行一项或多项操作。

以下示例演示如何：
+ 使用 [DescribeAlarms](https://docs.aws.amazon.com/aws-sdk-php/v3/api/api-monitoring-2010-08-01.html#describealarms) 描述警报。
+ 使用 [PutMetricAlarm](https://docs.aws.amazon.com/aws-sdk-php/v3/api/api-monitoring-2010-08-01.html#putmetricalarm) 创建警报。
+ 使用 [DeleteAlarms](https://docs.aws.amazon.com/aws-sdk-php/v3/api/api-monitoring-2010-08-01.html#deletealarms) 删除警报。

适用于 PHP 的 AWS SDKGitHub[ 上提供了](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/php/example_code)的所有示例代码。

## 凭证
<a name="examplecredentials"></a>

运行示例代码之前，请配置您的 AWS 凭证，如 [AWS 使用 适用于 PHP 的 AWS SDK 版本 3 进行身份验证](credentials.md) 中所述。然后导入 适用于 PHP 的 AWS SDK，如 [安装 适用于 PHP 的 AWS SDK 版本 3](getting-started_installation.md) 中所述。

## 描述警报
<a name="describe-alarms"></a>

 **导入**。

```
require 'vendor/autoload.php';

use Aws\CloudWatch\CloudWatchClient;
use Aws\Exception\AwsException;
```

 **示例代码** 

```
function describeAlarms($cloudWatchClient)
{
    try {
        $result = $cloudWatchClient->describeAlarms();

        $message = '';

        if (isset($result['@metadata']['effectiveUri'])) {
            $message .= 'Alarms at the effective URI of ' .
                $result['@metadata']['effectiveUri'] . "\n\n";

            if (isset($result['CompositeAlarms'])) {
                $message .= "Composite alarms:\n";

                foreach ($result['CompositeAlarms'] as $alarm) {
                    $message .= $alarm['AlarmName'] . "\n";
                }
            } else {
                $message .= "No composite alarms found.\n";
            }

            if (isset($result['MetricAlarms'])) {
                $message .= "Metric alarms:\n";

                foreach ($result['MetricAlarms'] as $alarm) {
                    $message .= $alarm['AlarmName'] . "\n";
                }
            } else {
                $message .= 'No metric alarms found.';
            }
        } else {
            $message .= 'No alarms found.';
        }

        return $message;
    } catch (AwsException $e) {
        return 'Error: ' . $e->getAwsErrorMessage();
    }
}

function describeTheAlarms()
{
    $cloudWatchClient = new CloudWatchClient([
        'profile' => 'default',
        'region' => 'us-east-1',
        'version' => '2010-08-01'
    ]);

    echo describeAlarms($cloudWatchClient);
}

// Uncomment the following line to run this code in an AWS account.
// describeTheAlarms();
```

## 创建警报
<a name="create-an-alarm"></a>

 **导入**。

```
require 'vendor/autoload.php';

use Aws\CloudWatch\CloudWatchClient;
use Aws\Exception\AwsException;
```

 **示例代码** 

```
function putMetricAlarm(
    $cloudWatchClient,
    $cloudWatchRegion,
    $alarmName,
    $namespace,
    $metricName,
    $dimensions,
    $statistic,
    $period,
    $comparison,
    $threshold,
    $evaluationPeriods
) {
    try {
        $result = $cloudWatchClient->putMetricAlarm([
            'AlarmName' => $alarmName,
            'Namespace' => $namespace,
            'MetricName' => $metricName,
            'Dimensions' => $dimensions,
            'Statistic' => $statistic,
            'Period' => $period,
            'ComparisonOperator' => $comparison,
            'Threshold' => $threshold,
            'EvaluationPeriods' => $evaluationPeriods
        ]);

        if (isset($result['@metadata']['effectiveUri'])) {
            if (
                $result['@metadata']['effectiveUri'] ==
                'https://monitoring.' . $cloudWatchRegion . '.amazonaws.com'
            ) {
                return 'Successfully created or updated specified alarm.';
            } else {
                return 'Could not create or update specified alarm.';
            }
        } else {
            return 'Could not create or update specified alarm.';
        }
    } catch (AwsException $e) {
        return 'Error: ' . $e->getAwsErrorMessage();
    }
}

function putTheMetricAlarm()
{
    $alarmName = 'my-ec2-resources';
    $namespace = 'AWS/Usage';
    $metricName = 'ResourceCount';
    $dimensions = [
        [
            'Name' => 'Type',
            'Value' => 'Resource'
        ],
        [
            'Name' => 'Resource',
            'Value' => 'vCPU'
        ],
        [
            'Name' => 'Service',
            'Value' => 'EC2'
        ],
        [
            'Name' => 'Class',
            'Value' => 'Standard/OnDemand'
        ]
    ];
    $statistic = 'Average';
    $period = 300;
    $comparison = 'GreaterThanThreshold';
    $threshold = 1;
    $evaluationPeriods = 1;

    $cloudWatchRegion = 'us-east-1';
    $cloudWatchClient = new CloudWatchClient([
        'profile' => 'default',
        'region' => $cloudWatchRegion,
        'version' => '2010-08-01'
    ]);

    echo putMetricAlarm(
        $cloudWatchClient,
        $cloudWatchRegion,
        $alarmName,
        $namespace,
        $metricName,
        $dimensions,
        $statistic,
        $period,
        $comparison,
        $threshold,
        $evaluationPeriods
    );
}

// Uncomment the following line to run this code in an AWS account.
// putTheMetricAlarm();
```

## 删除警报
<a name="delete-alarms"></a>

 **导入**。

```
require 'vendor/autoload.php';

use Aws\CloudWatch\CloudWatchClient;
use Aws\Exception\AwsException;
```

 **示例代码** 

```
function deleteAlarms($cloudWatchClient, $alarmNames)
{
    try {
        $result = $cloudWatchClient->deleteAlarms([
            'AlarmNames' => $alarmNames
        ]);

        return 'The specified alarms at the following effective URI have ' .
            'been deleted or do not currently exist: ' .
            $result['@metadata']['effectiveUri'];
    } catch (AwsException $e) {
        return 'Error: ' . $e->getAwsErrorMessage();
    }
}

function deleteTheAlarms()
{
    $alarmNames = array('my-alarm');

    $cloudWatchClient = new CloudWatchClient([
        'profile' => 'default',
        'region' => 'us-east-1',
        'version' => '2010-08-01'
    ]);

    echo deleteAlarms($cloudWatchClient, $alarmNames);
}

// Uncomment the following line to run this code in an AWS account.
// deleteTheAlarms();
```