python - Cloudfront 提供通过 AWS CDK Python 为 S3 存储桶源创建的访问被拒绝响应，无需公共(public)访问

Question

使用AWS CDK为S3存储桶创建了Cloud Front Web分配，无需公共(public)访问。能够创建原始访问身份并进行部署，但在成功部署后，我在浏览器上收到访问被拒绝的响应。

从 Origin 设置中授予存储桶读取权限将设置为“否”，手动将其设置为"is"一切都会正常工作，但此设置需要通过 AWS CDK 和 python 来实现。下面是我的代码。

from aws_cdk import aws_cloudfront as front, aws_s3 as s3

class CloudFrontStack(core.Stack):        
    def __init__(self, scope: core.Construct, idx: str, **kwargs) -> None:
        super().__init__(scope, idx, **kwargs)

        bucket = s3.Bucket.from_bucket_name(self, 'CloudFront',bucket_name="bucket_name")

        oia = aws_cloudfront.OriginAccessIdentity(self, 'OIA', comment="Created By CDK")
        bucket.grant_read(oia)

        s3_origin_source = aws_cloudfront.S3OriginConfig(s3_bucket_source=bucket, origin_access_identity=oia)

        source_config = aws_cloudfront.SourceConfiguration(s3_origin_source=s3_origin_source,
                                                           origin_path="bucket_path",
                                                           behaviors=[aws_cloudfront.Behavior(is_default_behavior=True)])

        aws_cloudfront.CloudFrontWebDistribution(self, "cloud_front_name",
                                                 origin_configs=[source_config],
                                                 comment='Cloud Formation created',
                                                 default_root_object='index.html')

我也尝试添加权限，如下所示，但仍然没有成功。

policyStatement = aws_iam.PolicyStatement()
policyStatement.add_resources()

policyStatement.add_actions('s3:GetBucket*');
policyStatement.add_actions('s3:GetObject*');
policyStatement.add_actions('s3:List*');
policyStatement.add_resources(bucket.bucket_arn);
policyStatement.add_canonical_user_principal(oia.cloud_front_origin_access_identity_s3_canonical_user_id);
code_bucket.add_to_resource_policy(policyStatement);

Answer 1

我尝试模仿这一点，并成功地将 Cloudfront 分发集成到私有(private) S3 存储桶。不过，我的堆栈使用了 TS。我确信将下面的代码与 Python 版本关联起来会很容易。假设dist

中有一个 index.html文件

aws-cdk v1.31.0(最新截至 2020 年 3 月 29 日)

import { App, Stack, StackProps } from '@aws-cdk/core';
import { BucketDeployment, Source } from '@aws-cdk/aws-s3-deployment';
import { CloudFrontWebDistribution, OriginAccessIdentity } from '@aws-cdk/aws-cloudfront';
import { BlockPublicAccess, Bucket, BucketEncryption } from '@aws-cdk/aws-s3';

export class HelloCdkStack extends Stack {
  constructor(scope: App, id: string, props?: StackProps) {
    super(scope, id, props);

    const myFirstBucket = new Bucket(this, 'MyFirstBucket', {
      versioned: true,
      encryption: BucketEncryption.S3_MANAGED,
      bucketName: 'cdk-example-bucket-for-test',
      websiteIndexDocument: 'index.html',
      blockPublicAccess: BlockPublicAccess.BLOCK_ALL
    });

    new BucketDeployment(this, 'DeployWebsite', {
      sources: [Source.asset('dist')],
      destinationBucket: myFirstBucket
    });

    const oia = new OriginAccessIdentity(this, 'OIA', {
      comment: "Created by CDK"
    });
    myFirstBucket.grantRead(oia);

    new CloudFrontWebDistribution(this, 'cdk-example-distribution', {
      originConfigs: [
        {
          s3OriginSource: {
            s3BucketSource: myFirstBucket,
            originAccessIdentity: oia
          },
          behaviors: [
            { isDefaultBehavior: true }
          ]
        }
      ]
    });
  }
}

== 更新 == [不带虚拟主机的 S3 存储桶]

这是一个示例，其中 S3 用作没有 Web 托管的源。它按预期工作。

import { App, Stack, StackProps } from '@aws-cdk/core';
import { BucketDeployment, Source } from '@aws-cdk/aws-s3-deployment';
import { CloudFrontWebDistribution, OriginAccessIdentity } from '@aws-cdk/aws-cloudfront';
import { BlockPublicAccess, Bucket, BucketEncryption } from '@aws-cdk/aws-s3';

export class CloudfrontS3Stack extends Stack {
  constructor(scope: App, id: string, props?: StackProps) {
    super(scope, id, props);

    // Create bucket (which is not a static website host), encrypted AES-256 and block all public access
    // Only Cloudfront access to S3 bucket
    const testBucket = new Bucket(this, 'TestS3Bucket', {
      encryption: BucketEncryption.S3_MANAGED,
      bucketName: 'cdk-static-asset-dmahapatro',
      blockPublicAccess: BlockPublicAccess.BLOCK_ALL
    });

    // Create Origin Access Identity to be use Canonical User Id in S3 bucket policy
    const originAccessIdentity = new OriginAccessIdentity(this, 'OAI', {
      comment: "Created_by_dmahapatro"
    });
    testBucket.grantRead(originAccessIdentity);

    // Create Cloudfront distribution with S3 as Origin
    const distribution = new CloudFrontWebDistribution(this, 'cdk-example-distribution', {
      originConfigs: [
        {
          s3OriginSource: {
            s3BucketSource: testBucket,
            originAccessIdentity: originAccessIdentity
          },
          behaviors: [
            { isDefaultBehavior: true }
          ]
        }
      ]
    });

    // Upload items in bucket and provide distribution to create invalidations
    new BucketDeployment(this, 'DeployWebsite', {
      sources: [Source.asset('dist')],
      destinationBucket: testBucket,
      distribution,
      distributionPaths: ['/images/*.png']
    });
  }
}

== 更新 == [导入 S3 存储桶，而不是在同一堆栈中创建]

当我们引用现有的 S3 存储桶时，可以重新创建问题。

原因:
问题的根本原因在于here in this line of code 。 autoCreatePolicy will always be false for an imported S3 bucket 。要使 addResourcePolicy 正常工作，导入的存储桶必须已有一个现有的存储桶策略，以便可以附加新的策略语句，或者手动创建新的 BucketPolicy 并添加策略语句。在下面的代码中，我手动创建了存储桶策略并添加了所需的策略语句。这非常接近 github issue #941但细微的区别在于在堆栈中创建存储桶与导入已创建的存储桶之间。

import { App, Stack, StackProps } from '@aws-cdk/core';
import { CloudFrontWebDistribution, OriginAccessIdentity } from '@aws-cdk/aws-cloudfront';
import { Bucket, BucketPolicy } from '@aws-cdk/aws-s3';
import { PolicyStatement } from '@aws-cdk/aws-iam';

export class CloudfrontS3Stack extends Stack {
  constructor(scope: App, id: string, props?: StackProps) {
    super(scope, id, props);

    const testBucket = Bucket.fromBucketName(this, 'TestBucket', 'dmahapatro-personal-bucket');

    // Create Origin Access Identity to be use Canonical User Id in S3 bucket policy
    const originAccessIdentity = new OriginAccessIdentity(this, 'OAI', {
      comment: "Created_by_dmahapatro"
    });

    // This does not seem to work if Bucket.fromBucketName is used
    // It works for S3 buckets which are created as part of this stack
    // testBucket.grantRead(originAccessIdentity);

    // Explicitly add Bucket Policy 
    const policyStatement = new PolicyStatement();
    policyStatement.addActions('s3:GetBucket*');
    policyStatement.addActions('s3:GetObject*');
    policyStatement.addActions('s3:List*');
    policyStatement.addResources(testBucket.bucketArn);
    policyStatement.addResources(`${testBucket.bucketArn}/*`);
    policyStatement.addCanonicalUserPrincipal(originAccessIdentity.cloudFrontOriginAccessIdentityS3CanonicalUserId);

    // testBucket.addToResourcePolicy(policyStatement);

    // Manually create or update bucket policy
    if( !testBucket.policy ) {
      new BucketPolicy(this, 'Policy', { bucket: testBucket }).document.addStatements(policyStatement);
    } else {
      testBucket.policy.document.addStatements(policyStatement);
    }

    // Create Cloudfront distribution with S3 as Origin
    const distribution = new CloudFrontWebDistribution(this, 'cdk-example-distribution', {
      originConfigs: [
        {
          s3OriginSource: {
            s3BucketSource: testBucket,
            originAccessIdentity: originAccessIdentity
          },
          behaviors: [
            { isDefaultBehavior: true }
          ]
        }
      ]
    });
  }
}