如何在App Engine上的后台任务中逐页生成pdf文档

import os
import requests
from google.cloud import storage
from google.cloud.storage.batch_get_objects import BatchGetObjectsResponse
from google.cloud.storage.object_download import ObjectDownload
from io import BytesIO
import iotextpdf
from iotextpdf import PdfReader
import iotextpdf
from iotextpdf import PdfWriter

# 连接到Google Cloud Platform
client = storage.Client()

# 获取存储桶中的所有对象
bucket_name = "my-bucket"
response = client.list_objects(bucket_name)

# 存储所有对象的下载URL
urls = []
for obj in response.get('Contents', []):
    url = obj['Key']
    urls.append(url)

# 创建PDF文档
pdf = iotextpdf.PdfReader()
pdf.add_page()

# 循环处理每个对象的下载URL
for url in urls:
    # 获取下载URL
    response = requests.get(url)
    if response.status_code != 200:
        print(f"Error: {response.status_code}")
        continue

    # 创建BytesIO对象
    buffer = BytesIO(response.content)

    # 读取PDF文档
    pdf.add_page(pdf.create_page(buffer))

    # 创建PDF文档
    doc = iotextpdf.PdfReader()
    doc.add_page()

    # 打印PDF文档
    doc.add_page(pdf.pages[0])

    # 保存PDF文档
    doc.save("output.pdf")