如何在cdk python中使用预先存在的亚马逊S3存储桶中的工件？

from aws_cdk import core
from aws_cdk import aws_s3 as s3
from aws_cdk import aws_s3_assets as s3_assets

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

        # 创建S3存储桶对象
        existing_bucket = s3.Bucket.from_bucket_name(self, "ExistingBucket", "your-existing-bucket-name")

        # 创建S3存储桶中的工件对象
        existing_object = s3_assets.Asset(self, "ExistingObject", path="path/to/existing-object")

        # 使用存储桶和工件对象创建CDK资源
        # ...

ec2_instance = ec2.Instance(self, "EC2Instance",
    instance_type=ec2.InstanceType("t2.micro"),
    machine_image=ec2.AmazonLinuxImage(),
    vpc=vpc,
    vpc_subnets=ec2.SubnetSelection(subnet_type=ec2.SubnetType.PUBLIC)
)

# 将S3存储桶中的工件复制到EC2实例的本地目录中
existing_object.grant_read(ec2_instance.role)
existing_object_s3_path = existing_object.s3_object_url.split("s3://")[1]
ec2_instance.user_data.add_commands(f"aws s3 cp s3://{existing_object_s3_path} /path/on/ec2/instance")