对于小型站点，使用七牛云存储的免费配额已足够为站点提供稳定、快速的存储服务
七牛云存储已有Python SDK，对它进行简单封装后，就可以直接在Flask中使用了，项目代码见GitHub上Flask-QiniuStorage。
使用示例代码：
from flask import Flask
from flask_qiniustorage import Qiniu
QINIU_ACCESS_KEY = '七牛 Access Key'
QINIU_SECRET_KEY = '七牛 Secret Key'
QINIU_BUCKET_NAME = '七牛空间名称'
QINIU_BUCKET_DOMAIN = '七牛空间对应域名'
app = Flask(__name__)
app.config.from_object(__name__)
qiniu_store = Qiniu(app)
# 或者
# qiniu_store = Qiniu()
# qiniu_store.init_app(app)
# 保存文件到七牛
@app.route('/save')
def save():
data = 'data to save'
filename = 'filename'
ret, info = qiniu_store.save(data, filename)
return str(ret)
# 删除七牛空间中的文件
@app.route('/delete')
def delete():
filename = 'filename'
ret, info = qiniu_store.delete(filename)
return str(ret)
# 根据文件名获取对应的公开URL
@app.route('/url')
def url():
filename = 'filename'
return qiniu_store.url(filename)