CloudFormation 跨区域参考

Question

当您在同一区域内运行多个 CloudFormation 堆栈时，您可以使用 CloudFormation Outputs

跨堆栈共享引用

但是，正如该文档强调的那样，输出不能用于跨区域引用。

You can't create cross-stack references across regions. You can use the intrinsic function Fn::ImportValue to import only values that have been exported within the same region.

您如何在 CloudFormation 中跨区域引用值？

举个例子，我有一个 Route 53 hosted zone deployed in us-east-1. However, I have a backend in us-west-2 that I want to create a DNS-validated ACM certificate，它需要对托管区域的引用，以便能够创建适当的 CNAME 来证明所有权。

我将如何从 us-west-2 中引用在 us-east-1 中创建的托管区域 ID？

Answer 1

我发现最简单的方法是将您要共享的参考（即本例中的托管区域 ID）写入 Systems Manager Parameter Store and then referencing that value in your "child" stack in the separate region using a custom resource。

幸运的是，如果您的模板是使用 Cloud Development Kit (CDK) 创建的，这将非常容易。

对于从SSM读取的自定义资源，你可以这样使用：

// ssm-parameter-reader.ts

import { Construct } from '@aws-cdk/core';
import { AwsCustomResource, AwsSdkCall } from '@aws-cdk/custom-resources';

interface SSMParameterReaderProps {
  parameterName: string;
  region: string;
}

export class SSMParameterReader extends AwsCustomResource {
  constructor(scope: Construct, name: string, props: SSMParameterReaderProps) {
    const { parameterName, region } = props;

    const ssmAwsSdkCall: AwsSdkCall = {
      service: 'SSM',
      action: 'getParameter',
      parameters: {
        Name: parameterName
      },
      region,
      physicalResourceId: Date.now().toString() // Update physical id to always fetch the latest version
    };

    super(scope, name, { onUpdate: ssmAwsSdkCall });
  }

  public getParameterValue(): string {
    return this.getData('Parameter.Value').toString();
  }
}

要将托管区域 ID 写入参数存储，您可以简单地执行以下操作：

// route53.ts (deployed in us-east-1)

import { PublicHostedZone } from '@aws-cdk/aws-route53';
import { StringParameter } from '@aws-cdk/aws-ssm';

export const ROUTE_53_HOSTED_ZONE_ID_SSM_PARAM = 'ROUTE_53_HOSTED_ZONE_ID_SSM_PARAM';

/**
 * Other Logic
 */

const hostedZone = new PublicHostedZone(this, 'WebsiteHostedZone', { zoneName: 'example.com' });

new StringParameter(this, 'Route53HostedZoneIdSSMParam', {
  parameterName: ROUTE_53_HOSTED_ZONE_ID_SSM_PARAM,
  description: 'The Route 53 hosted zone id for this account',
  stringValue: hostedZone.hostedZoneId
});

最后，您可以使用我们刚刚创建的自定义资源从该区域的参数存储中读取该值，并使用它在 us-west-2 中创建证书。

// acm.ts (deployed in us-west-2)

import { DnsValidatedCertificate } from '@aws-cdk/aws-certificatemanager';
import { PublicHostedZone } from '@aws-cdk/aws-route53';

import { ROUTE_53_HOSTED_ZONE_ID_SSM_PARAM } from './route53';
import { SSMParameterReader } from './ssm-parameter-reader';

/**
 * Other Logic
 */

const hostedZoneIdReader = new SSMParameterReader(this, 'Route53HostedZoneIdReader', {
  parameterName: ROUTE_53_HOSTED_ZONE_ID_SSM_PARAM,
  region: 'us-east-1'
});
const hostedZoneId: string = hostedZoneIdReader.getParameterValue();
const hostedZone = PublicHostedZone.fromPublicHostedZoneId(this, 'Route53HostedZone', hostedZoneId);

const certificate = new DnsValidatedCertificate(this, 'ApiGatewayCertificate', { 'pdx.example.com', hostedZone });

Answer 2

更新了cdk库，上面的代码需要修改如下：

import { Construct } from '@aws-cdk/core';
import { AwsCustomResource, AwsSdkCall } from '@aws-cdk/custom-resources';
import iam = require("@aws-cdk/aws-iam");

interface SSMParameterReaderProps {
  parameterName: string;
  region: string;
}

export class SSMParameterReader extends AwsCustomResource {
  constructor(scope: Construct, name: string, props: SSMParameterReaderProps) {
    const { parameterName, region } = props;

    const ssmAwsSdkCall: AwsSdkCall = {
      service: 'SSM',
      action: 'getParameter',
      parameters: {
        Name: parameterName
      },
      region,
      physicalResourceId: {id:Date.now().toString()} // Update physical id to always fetch the latest version
    };

    super(scope, name, { onUpdate: ssmAwsSdkCall,policy:{
        statements:[new iam.PolicyStatement({
        resources : ['*'],
        actions   : ['ssm:GetParameter'],
        effect:iam.Effect.ALLOW,
      }
      )]
    }});
  }

  public getParameterValue(): string {
    return this.getResponseField('Parameter.Value').toString();
  }
}

CloudFormation 跨区域参考

CloudFormation Cross-Region Reference

amazon-web-services

amazon-cloudformation

aws-cloudformation-custom-resource