假设我们有两个AWS账户：Account A和Account B。Account A中有一个Elastic Beanstalk环境，我们希望将它上面的应用程序代码打包并传送到Account B中的S3对象存储桶中，然后由Account B中的CodePipeline流水线进行自动化部署。下面是实现这个过程的几个步骤：

1. 在Account A中创建IAM Role，并为其赋予访问Account B S3存储桶的权限。

Resources:
  CrossAccountRole:
    Type: AWS::IAM::Role
    Properties:
      RoleName: "CrossAccountRole"
      AssumeRolePolicyDocument:
        Statement:
          - Effect: "Allow"
            Principal:
              AWS: !Ref AccountBARN
            Action:
              - "sts:AssumeRole"
      Policies:
        - PolicyName: "AccessS3Bucket"
          PolicyDocument:
            Statement:
              - Effect: Allow
                Action:
                  - "s3:ListBucket"
                  - "s3:GetBucketLocation"
                Resource: !Sub "arn:aws:s3:::${BucketName}"
              - Effect: Allow
                Action:
                  - "s3:GetObject"
                  - "s3:PutObject"
                Resource: !Sub "arn:aws:s3:::${BucketName}/*"

2. 在Account A中创建CodeBuild项目，用于打包应用程序代码并将其上传到Account B的S3存储桶中。

Resources:
  CodeBuildProject:
    Type: "AWS::CodeBuild::Project"
    Properties:
      Name: "CodeBuildProject"
      Artifacts:
        Type: "S3"
        Location: !Sub "arn:aws:s3:::${BucketName}/"
      Environment:
        Type: "LINUX_CONTAINER"
        ComputeType: "BUILD_GENERAL1_SMALL"
        Image: "aws/codebuild/docker:17.09.0"
        EnvironmentVariables:
          - Name: "S3_BUCKET"
            Value: !Sub "${BucketName}"
      ServiceRole: !