本文為英文版的機器翻譯版本，如內容有任何歧義或不一致之處，概以英文版為準。

# 範例：DynamoDB、CloudWatch 和 SNS
<a name="customize-environment-resources-dynamodb"></a>

此組態檔案會使用適用於 PHP 2 的 AWS SDK，將 DynamoDB 資料表設定為 PHP 型應用程式的工作階段處理常式。欲使用此範例，您必須具備 IAM 執行個體描述檔，本描述檔會新增至您環境的執行個體，並可用於存取 DynamoDB 資料表。

 您可從 [DynamoDB 工作階段支援範例](https://elasticbeanstalk.s3.amazonaws.com/extensions/PHP-DynamoDB-Session-Support.zip)下載本步驟要使用的範本。本範本內含下列檔案：
+ 範例應用程式 `index.php`
+ 組態檔案 ，用於建立和設定 DynamoDB 資料表和其他 AWS 資源`dynamodb.config`，並在 Elastic Beanstalk 環境中託管應用程式的 EC2 執行個體上安裝軟體
+ 組態檔案 `options.config`，會使用此特定安裝的設定來覆寫 `dynamodb.config` 的預設值

**`index.php`**

```
<?php

// Include the SDK using the Composer autoloader
require '../vendor/autoload.php';

use Aws\DynamoDb\DynamoDbClient;

// Grab the session table name and region from the configuration file
list($tableName, $region) = file(__DIR__ . '/../sessiontable');
$tableName = rtrim($tableName);
$region = rtrim($region);

// Create a DynamoDB client and register the table as the session handler
$dynamodb = DynamoDbClient::factory(array('region' => $region));
$handler = $dynamodb->registerSessionHandler(array('table_name' => $tableName, 'hash_key' => 'username'));

// Grab the instance ID so we can display the EC2 instance that services the request
$instanceId = file_get_contents("http://169.254.169.254/latest/meta-data/instance-id");
?>
<h1>Elastic Beanstalk PHP Sessions Sample</h1>
<p>This sample application shows the integration of the Elastic Beanstalk PHP
container and the session support for DynamoDB from the AWS SDK for PHP 2.
Using DynamoDB session support, the application can be scaled out across
multiple web servers. For more details, see the
<a href="https://aws.amazon.com/php/">PHP Developer Center</a>.</p>

<form id="SimpleForm" name="SimpleForm" method="post" action="index.php">
<?php
echo 'Request serviced from instance ' . $instanceId . '<br/>';
echo '<br/>';

if (isset($_POST['continue'])) {
  session_start();
  $_SESSION['visits'] = $_SESSION['visits'] + 1;
  echo 'Welcome back ' . $_SESSION['username'] . '<br/>';
  echo 'This is visit number ' . $_SESSION['visits'] . '<br/>';
  session_write_close();
  echo '<br/>';
  echo '<input type="Submit" value="Refresh" name="continue" id="continue"/>';
  echo '<input type="Submit" value="Delete Session" name="killsession" id="killsession"/>';
} elseif (isset($_POST['killsession'])) {
  session_start();
  echo 'Goodbye ' . $_SESSION['username'] . '<br/>';
  session_destroy();
  echo 'Username: <input type="text" name="username" id="username" size="30"/><br/>';
  echo '<br/>';
  echo '<input type="Submit" value="New Session" name="newsession" id="newsession"/>';
} elseif (isset($_POST['newsession'])) {
  session_start();
  $_SESSION['username'] = $_POST['username'];
  $_SESSION['visits'] = 1;
  echo 'Welcome to a new session ' . $_SESSION['username'] . '<br/>';
  session_write_close();
  echo '<br/>';
  echo '<input type="Submit" value="Refresh" name="continue" id="continue"/>';
  echo '<input type="Submit" value="Delete Session" name="killsession" id="killsession"/>';
} else {
  echo 'To get started, enter a username.<br/>';
  echo '<br/>';
  echo 'Username: <input type="text" name="username" id="username" size="30"/><br/>';
  echo '<input type="Submit" value="New Session" name="newsession" id="newsession"/>';
}
?>
</form>
```

**`.ebextensions/dynamodb.config`**

```
Resources:
  SessionTable:
    Type: AWS::DynamoDB::Table
    Properties:
      KeySchema: 
        HashKeyElement:
          AttributeName:
            Fn::GetOptionSetting:
              OptionName : SessionHashKeyName
              DefaultValue: "username"
          AttributeType:
            Fn::GetOptionSetting:
              OptionName : SessionHashKeyType
              DefaultValue: "S"
      ProvisionedThroughput:
        ReadCapacityUnits:
          Fn::GetOptionSetting:
            OptionName : SessionReadCapacityUnits
            DefaultValue: 1
        WriteCapacityUnits:
          Fn::GetOptionSetting:
            OptionName : SessionWriteCapacityUnits
            DefaultValue: 1

  SessionWriteCapacityUnitsLimit:
    Type: AWS::CloudWatch::Alarm
    Properties:
      AlarmDescription: { "Fn::Join" : ["", [{ "Ref" : "AWSEBEnvironmentName" }, " write capacity limit on the session table." ]]}
      Namespace: "AWS/DynamoDB"
      MetricName: ConsumedWriteCapacityUnits
      Dimensions:
        - Name: TableName
          Value: { "Ref" : "SessionTable" }
      Statistic: Sum
      Period: 300
      EvaluationPeriods: 12
      Threshold:
          Fn::GetOptionSetting:
            OptionName : SessionWriteCapacityUnitsAlarmThreshold
            DefaultValue: 240
      ComparisonOperator: GreaterThanThreshold
      AlarmActions:
        - Ref: SessionAlarmTopic
      InsufficientDataActions:
        - Ref: SessionAlarmTopic

  SessionReadCapacityUnitsLimit:
    Type: AWS::CloudWatch::Alarm
    Properties:
      AlarmDescription: { "Fn::Join" : ["", [{ "Ref" : "AWSEBEnvironmentName" }, " read capacity limit on the session table." ]]}
      Namespace: "AWS/DynamoDB"
      MetricName: ConsumedReadCapacityUnits
      Dimensions:
        - Name: TableName
          Value: { "Ref" : "SessionTable" }
      Statistic: Sum
      Period: 300
      EvaluationPeriods: 12
      Threshold:
          Fn::GetOptionSetting:
            OptionName : SessionReadCapacityUnitsAlarmThreshold
            DefaultValue: 240
      ComparisonOperator: GreaterThanThreshold
      AlarmActions:
        - Ref: SessionAlarmTopic
      InsufficientDataActions:
        - Ref: SessionAlarmTopic

  SessionThrottledRequestsAlarm:
    Type: AWS::CloudWatch::Alarm
    Properties:
      AlarmDescription: { "Fn::Join" : ["", [{ "Ref" : "AWSEBEnvironmentName" }, ": requests are being throttled." ]]}
      Namespace: AWS/DynamoDB
      MetricName: ThrottledRequests
      Dimensions:
        - Name: TableName
          Value: { "Ref" : "SessionTable" }
      Statistic: Sum
      Period: 300
      EvaluationPeriods: 1
      Threshold: 
        Fn::GetOptionSetting:
          OptionName: SessionThrottledRequestsThreshold
          DefaultValue: 1
      ComparisonOperator: GreaterThanThreshold
      AlarmActions:
        - Ref: SessionAlarmTopic
      InsufficientDataActions:
        - Ref: SessionAlarmTopic

  SessionAlarmTopic:
    Type: AWS::SNS::Topic
    Properties:
      Subscription:
        - Endpoint:
            Fn::GetOptionSetting:
              OptionName: SessionAlarmEmail
              DefaultValue: "nobody@amazon.com"
          Protocol: email

files:
  "/var/app/sessiontable":
    mode: "000444"
    content: |
      `{"Ref" : "SessionTable"}`
      `{"Ref" : "AWS::Region"}`

  "/var/app/composer.json":
    mode: "000744"
    content:
      {
        "require": {
           "aws/aws-sdk-php": "*"
        }
      }

container_commands:
 "1-install-composer":
   command: "cd /var/app; curl -s http://getcomposer.org/installer | php"
 "2-install-dependencies":
   command: "cd /var/app; php composer.phar install"
 "3-cleanup-composer":
   command: "rm -Rf /var/app/composer.*"
```

在範本組態檔案中，我們首先建立 DynamoDB 資料表，並設定其主金鑰結構與容量單位，以配置足夠的資源來提供請求的傳輸量。接著，我們建立 `WriteCapacity` 和 `ReadCapacity` 的 CloudWatch 警示。我們會建立 SNS 主題，若超過警示閾值，此主題會傳送電子郵件至「nobody@amazon.com」。

為環境建立和設定 AWS 資源之後，我們需要自訂 EC2 執行個體。我們使用 `files`金鑰將 DynamoDB 資料表的詳細資訊傳遞至環境中的 EC2 執行個體，並在適用於 PHP 2 的 AWS SDK 的 `composer.json` 檔案中新增「需要」。最後，我們執行容器命令來安裝 Composer 和所需依存項目，然後移除安裝程式。

**`.ebextensions/options.config`**

```
option_settings:
  "aws:elasticbeanstalk:customoption":
     SessionHashKeyName                      : username
     SessionHashKeyType                      : S
     SessionReadCapacityUnits                : 1
     SessionReadCapacityUnitsAlarmThreshold  : 240
     SessionWriteCapacityUnits               : 1 
     SessionWriteCapacityUnitsAlarmThreshold : 240
     SessionThrottledRequestsThreshold       : 1
     SessionAlarmEmail                       : me@example.com
```

使用您希望接收警示通知的電子郵件，取代 SessionAlarmEmail 的值。`options.config` 檔案內含部分定義於 `dynamodb.config` 的變數的值。例如，`dynamodb.config` 內含下列行：

```
Subscription:
  - Endpoint:
      Fn::GetOptionSetting:
        OptionName: SessionAlarmEmail
        DefaultValue: "nobody@amazon.com"
```

這些行會指示 Elastic Beanstalk 自組態檔案 (在我們的範例應用程式為 `options.config`) 中的 **SessionAlarmEmail** 值，取得 **Endpoint** (端點) 屬性的值，該組態檔案中的 option\$1settings 區段帶有 **aws:elasticbeanstalk:customoption** 區段，其中包含要使用之實際值的名稱-值對。在上述範例中，這表示 **SessionAlarmEmail** 將指派 `nobody@amazon.com` 值。

如需本範例所使用的 CloudFormation 資源的詳細資訊，請參閱下列參考：
+ [AWS::DynamoDB::Table](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-dynamodb-table.html)
+ [AWS::CloudWatch::Alarm](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-cw-alarm.html)
+ [AWS::SNS::Topic](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-sns-topic.html)