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使用 Amazon S3 事件通知加速网络爬取

您可以将爬网程序配置为使用 Amazon S3 事件来查找任何更改，而不是列出 Amazon S3 或 Data Catalog 目标中的对象。此功能使用 Amazon S3 事件，通过列出触发事件的子文件夹中的所有文件，而不是列出完整的 Amazon S3 或 Data Catalog 目标，来识别两次网络爬取之间的更改，从而缩短了重新爬网时间。

第一次网络爬取会列出目标中的所有 Amazon S3 对象。第一次成功爬取之后，您可以选择手动重新爬取或按设定计划重新爬取。爬网程序只会列出这些事件中的对象，而不会列出所有对象。

迁移到基于 Amazon S3 事件的爬网程序的优点包括：

Amazon S3 事件网络爬取基于爬网程序调度，从 SQS 队列中使用 Amazon S3 事件来运行。如果队列中没有事件，则无需支付费用。Amazon S3 事件可以配置为直接进入 SQS 队列，或者在多个用户需要相同事件的情况下，也可以配置为 SNS 和 SQS 的组合。有关更多信息，请参阅 为 Amazon S3 事件通知设置账户。

在事件模式下创建和配置爬网程序之后，第一次网络爬取将在列表模式下通过执行 Amazon S3 或 Data Catalog 目标的完整列表来运行。第一次成功网络爬取后将使用 Amazon S3 事件，以下日志可确认网络爬取的运行：“网络爬取正在使用 Amazon S3 事件来运行。”

创建 Amazon S3 事件网络爬取并更新可能影响网络爬取的爬网程序属性后，网络爬取将在列表模式下运行，并添加以下日志：“网络爬取未在 S3 事件模式下运行”。

目录目标

当目标为 Data Catalog 时，爬网程序会利用更改（例如，表中的额外分区）更新 Data Catalog 中的现有表。

为 Amazon S3 事件通知设置账户

本节介绍如何为 Amazon S3 事件通知设置账户，并提供使用脚本或 Amazon Glue 控制台执行此操作的说明。

先决条件

完成以下设置任务。请注意，括号中的值引用了脚本中的可配置设置。

您也可以使用 CloudFormation 堆栈创建您的资源。完成以下步骤：

限制:

要使用基于 Amazon S3 事件的爬网程序，您应该在 S3 存储桶上启用事件通知，并使用从与 S3 目标相同的前缀中筛选的事件，并存储在 SQS 中。您可以按照演练：为存储桶配置通知中的步骤或使用 用于从目标生成 SQS 和配置 Amazon S3 事件的脚本 通过控制台设置 SQS 和事件通知。

SQS 策略

添加以下 SQS 策略，需要附上爬网程序使用的角色。

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "VisualEditor0",
            "Effect": "Allow",
            "Action": [
                "sqs:DeleteMessage",
                "sqs:GetQueueUrl",
                "sqs:ListDeadLetterSourceQueues",                
                "sqs:ReceiveMessage",
                "sqs:GetQueueAttributes",
                "sqs:ListQueueTags",
                "sqs:SetQueueAttributes",
                "sqs:PurgeQueue"
            ],
            "Resource": "arn:aws:sqs:{region}:{accountID}:cfn-sqs-queue"
        }
    ]
}

用于从目标生成 SQS 和配置 Amazon S3 事件的脚本

确保满足先决条件后，可以运行以下 Python 脚本来创建 SQS。将可配置设置替换为根据先决条件准备的名称。

Amazon SQS 会设置可见性超时，即 Amazon SQS 阻止其他用户接收并处理消息的一段时间。将可见性超时设置为大致等于网络爬取运行时。

#!venv/bin/python
import boto3
import botocore
 
#---------Start : READ ME FIRST ----------------------#
# 1. Purpose of this script is to create the SQS, SNS and enable S3 bucket notification.
#     The following are the operations performed by the scripts:
#      a. Enable S3 bucket notification to trigger 's3:ObjectCreated:' and 's3:ObjectRemoved:' events.
#      b. Create SNS topic for fan out.
#      c. Create SQS queue for saving events which will be consumed by the crawler.
#          SQS Event Queue ARN will be used to create the crawler after running the script.
# 2. This script does not create the crawler.
# 3. SNS topic is created to support FAN out of S3 events. If S3 event is also used by another
#    purpose, SNS topic created by the script can be used.
# 1. Creation of bucket is an optional step.
#    To create a bucket set create_bucket variable to true.
# 2. The purpose of crawler_name is to easily locate the SQS/SNS.
#     crawler_name is used to create SQS and SNS with the same name as crawler.
# 3. 'folder_name' is the target of crawl inside the specified bucket 's3_bucket_name'
#
#---------End : READ ME FIRST ------------------------#
 
 
#--------------------------------#
# Start : Configurable settings  #
#--------------------------------#
 
#Create
region = 'us-west-2'
s3_bucket_name = 's3eventtestuswest2'
folder_name = "test"
crawler_name = "test33S3Event"
sns_topic_name = crawler_name
sqs_queue_name = sns_topic_name
create_bucket = False
 
#-------------------------------#
# End : Configurable settings   #
#-------------------------------#
 
# Define aws clients
dev = boto3.session.Session(profile_name='myprofile')
boto3.setup_default_session(profile_name='myprofile')
s3 = boto3.resource('s3', region_name=region)
sns = boto3.client('sns', region_name=region)
sqs = boto3.client('sqs', region_name=region)
client = boto3.client("sts")
account_id = client.get_caller_identity()["Account"]
queue_arn = ""
 
 
def print_error(e):
    print(e.message + ' RequestId: ' + e.response['ResponseMetadata']['RequestId'])
 
def create_s3_bucket(bucket_name, client):
    bucket = client.Bucket(bucket_name)
    try:
        if not create_bucket:
            return True
        response = bucket.create(
            ACL='private',
            CreateBucketConfiguration={
                'LocationConstraint': region
            },
        )
        return True
    except botocore.exceptions.ClientError as e:
        print_error(e)
        if 'BucketAlreadyOwnedByYou' in e.message:  # we own this bucket so continue
            print('We own the bucket already. Lets continue...')
            return True
    return False
 
def create_s3_bucket_folder(bucket_name, client, directory_name):
    s3.put_object(Bucket=bucket_name, Key=(directory_name + '/'))
 
def set_s3_notification_sns(bucket_name, client, topic_arn):
    bucket_notification = client.BucketNotification(bucket_name)
    try:
 
        response = bucket_notification.put(
            NotificationConfiguration={
                'TopicConfigurations': [
                    {
                        'Id' : crawler_name,
                        'TopicArn': topic_arn,
                        'Events': [
                            's3:ObjectCreated:*',
                            's3:ObjectRemoved:*',
 
                        ],
                        'Filter' :  {'Key': {'FilterRules': [{'Name': 'prefix', 'Value': folder_name}]}}
                    },
                ]
            }
        )
        return True
    except botocore.exceptions.ClientError as e:
        print_error(e)
    return False
 
 
def create_sns_topic(topic_name, client):
    try:
        response = client.create_topic(
            Name=topic_name
        )
        return response['TopicArn']
    except botocore.exceptions.ClientError as e:
        print_error(e)
    return None
 
def set_sns_topic_policy(topic_arn, client, bucket_name):
    try:
        response = client.set_topic_attributes(
            TopicArn=topic_arn,
            AttributeName='Policy',
            AttributeValue='''{
              "Version": "2008-10-17",
              "Id": "s3-publish-to-sns",
              "Statement": [{
                  "Effect": "Allow",
                  "Principal": { "AWS" : "*" },
                  "Action": [ "SNS:Publish" ],
                  "Resource": "%s",
                  "Condition": {
                    "StringEquals": {
                        "AWS:SourceAccount": "%s"
                      },
                      "ArnLike": {
                          "aws:SourceArn": "arn:aws:s3:*:*:%s"
                      }
                  }
              }]
  }''' % (topic_arn, account_id, bucket_name)
        )
        return True
    except botocore.exceptions.ClientError as e:
        print_error(e)
 
    return False
 
 
def subscribe_to_sns_topic(topic_arn, client, protocol, endpoint):
    try:
        response = client.subscribe(
            TopicArn=topic_arn,
            Protocol=protocol,
            Endpoint=endpoint
        )
        return response['SubscriptionArn']
    except botocore.exceptions.ClientError as e:
        print_error(e)
    return None
 
 
def create_sqs_queue(queue_name, client):
    try:
        response = client.create_queue(
            QueueName=queue_name,
        )
        return response['QueueUrl']
    except botocore.exceptions.ClientError as e:
        print_error(e)
    return None
 
 
def get_sqs_queue_arn(queue_url, client):
    try:
        response = client.get_queue_attributes(
            QueueUrl=queue_url,
            AttributeNames=[
                'QueueArn',
            ]
        )
        return response['Attributes']['QueueArn']
    except botocore.exceptions.ClientError as e:
        print_error(e)
    return None
 
def set_sqs_policy(queue_url, queue_arn, client, topic_arn):
    try:
        response = client.set_queue_attributes(
            QueueUrl=queue_url,
            Attributes={
                'Policy': '''{
                  "Version": "2012-10-17",
                  "Id": "AllowSNSPublish",
                  "Statement": [
                    {
                      "Sid": "AllowSNSPublish01",
                      "Effect": "Allow",
                      "Principal": "*",
                      "Action": "SQS:SendMessage",
                      "Resource": "%s",
                      "Condition": {
                        "ArnEquals": {
                          "aws:SourceArn": "%s"
                        }
                      }
                    }
                  ]
}''' % (queue_arn, topic_arn)
            }
        )
        return True
    except botocore.exceptions.ClientError as e:
        print_error(e)
    return False
 
 
if __name__ == "__main__":
    print('Creating S3 bucket %s.' % s3_bucket_name)
    if create_s3_bucket(s3_bucket_name, s3):
        print('\nCreating SNS topic %s.' % sns_topic_name)
        topic_arn = create_sns_topic(sns_topic_name, sns)
        if topic_arn:
            print('SNS topic created successfully: %s' % topic_arn)
 
            print('Creating SQS queue %s' % sqs_queue_name)
            queue_url = create_sqs_queue(sqs_queue_name, sqs)
            if queue_url is not None:
                print('Subscribing sqs queue with sns.')
                queue_arn = get_sqs_queue_arn(queue_url, sqs)
                if queue_arn is not None:
                    if set_sqs_policy(queue_url, queue_arn, sqs, topic_arn):
                        print('Successfully configured queue policy.')
                        subscription_arn = subscribe_to_sns_topic(topic_arn, sns, 'sqs', queue_arn)
                        if subscription_arn is not None:
                            if 'pending confirmation' in subscription_arn:
                                print('Please confirm SNS subscription by visiting the subscribe URL.')
                            else:
                                print('Successfully subscribed SQS queue: ' + queue_arn)
                        else:
                            print('Failed to subscribe SNS')
                    else:
                        print('Failed to set queue policy.')
                else:
                    print("Failed to get queue arn for %s" % queue_url)
            # ------------ End subscriptions to SNS topic -----------------
 
            print('\nSetting topic policy to allow s3 bucket %s to publish.' % s3_bucket_name)
            if set_sns_topic_policy(topic_arn, sns, s3_bucket_name):
                print('SNS topic policy added successfully.')
                if set_s3_notification_sns(s3_bucket_name, s3, topic_arn):
                    print('Successfully configured event for S3 bucket %s' % s3_bucket_name)
                    print('Create S3 Event Crawler using SQS ARN %s' % queue_arn)
                else:
                    print('Failed to configure S3 bucket notification.')
            else:
                print('Failed to add SNS topic policy.')
        else:
            print('Failed to create SNS topic.')

使用控制台为 Amazon S3 事件通知设置爬网程序（Amazon S3 目标）

要针对 Amazon S3 目标使用 Amazon Glue 控制台为 Amazon S3 事件通知设置爬网程序，请执行以下操作：

使用 Amazon CLI 为 Amazon S3 事件通知设置爬网程序

以下是在 Amazon S3 目标存储桶上创建 SQS 队列和设置事件通知的 Amazon S3 Amazon CLI 调用示例。

S3 Event AWS CLI
aws sqs create-queue --queue-name MyQueue --attributes file://create-queue.json
create-queue.json
```
{
    "Policy": {
        "Version": "2012-10-17",
        "Id": "example-ID",
        "Statement": [
            {
                "Sid": "example-statement-ID",
                "Effect": "Allow",
                "Principal": {
                    "Service": "s3.amazonaws.com"
                },
                "Action": [
                    "SQS:SendMessage"
                ],
                "Resource": "SQS-queue-ARN",
                "Condition": {
                    "ArnLike": {
                        "aws:SourceArn": "arn:aws:s3:*:*:awsexamplebucket1"
                    },
                    "StringEquals": {
                        "aws:SourceAccount": "bucket-owner-account-id"
                    }
                }
            }
        ]
    }
}
```
aws s3api put-bucket-notification-configuration --bucket customer-data-pdx --notification-configuration file://s3-event-config.json
s3-event-config.json
```
{
    "QueueConfigurations": [
        {
          "Id": "s3event-sqs-queue",
          "QueueArn": "arn:aws:sqs:{region}:{account}:queuename",
          "Events": [
                "s3:ObjectCreated:*",
                "s3:ObjectRemoved:*"
          ],
          "Filter": {
              "Key": {
                  "FilterRules": [
                      {
                          "Name": "Prefix",
                          "Value": "/json"
                      }
                  ]
              }
          }
        }
    ]
}
```
Create Crawler:
              
          

使用控制台为 Amazon S3 事件通知设置爬网程序（Data Catalog 目标）

当您有目录目标时，请使用 Amazon Glue 控制台为 Amazon S3 事件通知设置爬网程序：