前言
一个应用可能已经使用对象存储（Object Storage Service，简称OSS）来存放用户上传的图片，用户可以实现一个函数去下载图片进行处理，并将结果存入OSS或者其他服务。如果OSS能够帮助我们关注新上传的图片，并且自动的去调用执行相应的处理函数，用户就不需要再去自己调用函数了，从而简化了开发和使用流程。
函数计算提供了一种事件驱动的计算模型。函数的执行是由事件驱动的，函数计算触发器描述了一组规则，当某个事件满足这些规则，事件源就会触发相应的函数。
repo 工程： fc-decompress-oss
示例内容
在本教程示例中，一个被存入OSS的文件，如果它是以source/为前缀，并且后缀是.gz .tar .zip的文件，那么OSS就会自动的调用相应的函数进行解压处理。
# -*- coding: utf-8 -*-
import oss2, json
import gzip
import tarfile
import zipfile
import os
import cStringIO
# This template code can decompress the following three types of compression files.
#.gz .tar .zip
# if you want uncompress rar or for more info
# please refer to https://yq.aliyun.com/articles/468050?spm=a2c4e.11153959.teamhomeleft.1.1534d3c20HYMx5
def handler(event, context):
"""
The object from OSS will be decompressed automatically .
param: event: The OSS event json string. Including oss object uri and other information.
param: context: The function context, including credential and runtime info.
For detail info, please refer to https://help.aliyun.com/document_detail/56316.html#using-context
"""
evt_lst = json.loads(event)
creds = context.credentials
# Required by OSS sdk
auth=oss2.StsAuth(
creds.access_key_id,
creds.access_key_secret,
creds.security_token)
evt = evt_lst['events'][0]
bucket_name = evt['oss']['bucket']['name']
endpoint = 'oss-' + evt['region'] + '.aliyuncs.com'
bucket = oss2.Bucket(auth, endpoint, bucket_name)
object_name = evt['oss']['object']['key']
"""
When a source/ prefix object is placed in an OSS, it is hoped that the object will be decompressed and then stored in the OSS as processed/ prefixed.
For example, source/a.zip will be processed as processed/a/...
"Source /", "processed/" can be changed according to the user's requirements.
"""
newKey = object_name.replace("source/", "processed/")
remote_stream = bucket.get_object(object_name)
if not remote_stream:
raise RuntimeError('failed to get oss object. bucket: %s. object: %s' % (bucket_name, object_name))
print 'download object from oss success: {}'.format(object_name)
file_type = os.path.splitext(object_name)[1]
if file_type == ".gz":
data = cStringIO.StringIO(remote_stream.read())
newKey = newKey.strip()[:-3]
with gzip.GzipFile(mode = 'rb', fileobj = data) as f:
r_data = f.read()
bucket.put_object(newKey, r_data)
elif file_type == ".tar":
data = cStringIO.StringIO(remote_stream.read())
with tarfile.TarFile(mode = 'r', fileobj = data) as tar:
newKey.replace(".tar", "")
names = tar.getnames()
for name in names:
r = tar.extractfile(name)
if r: # filter folder
bucket.put_object(newKey + name, r.read())
r.close()
elif file_type == ".zip":
data = cStringIO.StringIO(remote_stream.read())
with zipfile.ZipFile(data,"r") as zip_file:
newKey.replace(".zip", "")
for name in zip_file.namelist():
file = zip_file.open(name)
r_data = file.read()
if r_data: # filter folder
bucket.put_object(newKey + name, r_data)
file.close()FAQ
如果是文件是后缀是.rar ，怎么解？
rar 这种格式如果用python，需要依赖第三方module和二进制文件，附件提供代码下载
