cdk bootstrapが何者なのか正面から向き合う

# CDKプロジェクトディレクトリの直下にいることを確認
$ pwd 
/Users/nogusan/cdk-boostrap-revealing

# ブートストラップテンプレートの中身を確認
# 2通りのコマンドがありますが、2つ目のほうがテンプレートファイルの在処がわかり、実体を体感しやすいかもしれませんね。
$ npx cdk bootstrap --show-template
$ cat ./node_modules/aws-cdk/lib/api/bootstrap/bootstrap-template.yaml

Resources:
    # 一部省略
    StagingBucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName:
        Fn::If:
          - HasCustomFileAssetsBucketName
          - Fn::Sub: "${FileAssetsBucketName}"
          - Fn::Sub: cdk-${Qualifier}-assets-${AWS::AccountId}-${AWS::Region}
      AccessControl: Private
      BucketEncryption:
        ServerSideEncryptionConfiguration:
          - ServerSideEncryptionByDefault:
              SSEAlgorithm: aws:kms
              KMSMasterKeyID:
                Fn::If:
                  - CreateNewKey
                  - Fn::Sub: "${FileAssetsBucketEncryptionKey.Arn}"
                  - Fn::If:
                    - UseAwsManagedKey
                    - Ref: AWS::NoValue
                    - Fn::Sub: "${FileAssetsBucketKmsKeyId}"
        # これ以降も省略

import * as cdk from 'aws-cdk-lib';
import { Construct } from 'constructs';
import * as s3 from 'aws-cdk-lib/aws-s3';

export class S3SampleStack extends cdk.Stack {
  constructor(scope: Construct, id: string, props?: cdk.StackProps) {
    super(scope, id, props);

    // S3 バケットを作成
    new s3.Bucket(this, 'SampleBucket', {
      bucketName: 'nogusan-sample-bucket',
    });
  }
}

const app = new cdk.App();
new S3SampleStack(app, 'S3SampleStack');

npx cdk deploy S3SampleStack

✨  Synthesis time: 3.52s

S3SampleStack: start: Building bee2ac2695adc44e1a951e90fdaf020f5ebd61163862402307d569f1418934cf:current_account-current_region
S3SampleStack: success: Built bee2ac2695adc44e1a951e90fdaf020f5ebd61163862402307d569f1418934cf:current_account-current_region
S3SampleStack: start: Publishing bee2ac2695adc44e1a951e90fdaf020f5ebd61163862402307d569f1418934cf:current_account-current_region
S3SampleStack: success: Published bee2ac2695adc44e1a951e90fdaf020f5ebd61163862402307d569f1418934cf:current_account-current_region
S3SampleStack: deploying... [1/1]
S3SampleStack: creating CloudFormation changeset...
S3SampleStack | 0/3 | 18:19:56 | REVIEW_IN_PROGRESS   | AWS::CloudFormation::Stack | S3SampleStack User Initiated
S3SampleStack | 0/3 | 18:20:02 | CREATE_IN_PROGRESS   | AWS::CloudFormation::Stack | S3SampleStack User Initiated
S3SampleStack | 0/3 | 18:20:04 | CREATE_IN_PROGRESS   | AWS::S3::Bucket    | SampleBucket (SampleBucket7F6F8160) 
S3SampleStack | 0/3 | 18:20:04 | CREATE_IN_PROGRESS   | AWS::CDK::Metadata | CDKMetadata/Default (CDKMetadata) 
S3SampleStack | 0/3 | 18:20:05 | CREATE_IN_PROGRESS   | AWS::CDK::Metadata | CDKMetadata/Default (CDKMetadata) Resource creation Initiated
S3SampleStack | 1/3 | 18:20:05 | CREATE_COMPLETE      | AWS::CDK::Metadata | CDKMetadata/Default (CDKMetadata) 
S3SampleStack | 1/3 | 18:20:06 | CREATE_IN_PROGRESS   | AWS::S3::Bucket    | SampleBucket (SampleBucket7F6F8160) Resource creation Initiated
S3SampleStack | 2/3 | 18:20:19 | CREATE_COMPLETE      | AWS::S3::Bucket    | SampleBucket (SampleBucket7F6F8160) 
S3SampleStack | 3/3 | 18:20:20 | CREATE_COMPLETE      | AWS::CloudFormation::Stack | S3SampleStack 

 ✅  S3SampleStack

✨  Deployment time: 28.76s

Stack ARN:
arn:aws:cloudformation:ap-northeast-1:XXXXXXXXXXXX:stack/S3SampleStack/05339d10-eb7e-11ef-abe7-0e65a27aa8bd

✨  Total time: 32.28s

$ aws s3 cp s3://cdk-hnb659fds-assets-XXXXXXXXXXXX-ap-northeast-1/bee2ac2695adc44e1a951e90fdaf020f5ebd61163862402307d569f1418934cf.json - | jq

{
  "Resources": {
    "SampleBucket7F6F8160": {
      "Type": "AWS::S3::Bucket",
      "Properties": {
        "BucketName": "nogusan-sample-bucket"
      },
      "UpdateReplacePolicy": "Retain",
      "DeletionPolicy": "Retain",
      "Metadata": {
        "aws:cdk:path": "S3SampleStack/SampleBucket/Resource"
      }
    },
    # これ以降の出力は省略
}

Parameters:
    Qualifier:
    Description: An identifier to distinguish multiple bootstrap stacks in the same environment
    Default: hnb659fds
Resouces:
    StagingBucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName:
        Fn::If:
          - HasCustomFileAssetsBucketName
          - Fn::Sub: "${FileAssetsBucketName}"
          - Fn::Sub: cdk-${Qualifier}-assets-${AWS::AccountId}-${AWS::Region}