Generate a resumable upload URL for Google Cloud Storage

resumable.py

import json
import os
from oauth2client.service_account import ServiceAccountCredentials
import httplib2

GCP_CREDENTIALS_FILE = os.getenv('GCP_CREDENTIALS_FILE', 'client-secret.json')
GCS_UPLOAD_URL_PATTERN = 'https://www.googleapis.com/upload/storage'+ \
                         '/v1/b/{bucket}/o?uploadType=resumable'

def get_upload_url(bucket, filename, content_length, content_type='application/octet-stream'):
    """Generate a resumable upload URL for Google Cloud Storage"""

    credentials = ServiceAccountCredentials.from_json_keyfile_name(
        'client-secret.json',
        ('https://www.googleapis.com/auth/devstorage.read_write',),
    )
    http = httplib2.Http()
    credentials.authorize(http)
    url = GCS_UPLOAD_URL_PATTERN.format(bucket=bucket)
    body = json.dumps({
        'name': filename,
    }).encode('UTF-8')
    headers = {
        'X-Upload-Content-Type': content_type,
        'X-Upload-Content-Length': content_length,
        'Content-Type': 'application/json; charset=UTF-8',
        'Content-Length': len(body),
    }
    resp_headers, resp_body = http.request(url, method='POST', headers=headers, body=body)
    return resp_headers['location']