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vishnu 3.0.0

Sessions for the Google App Engine Python runtime

Sessions for python WSGI applications.

Features

  • Cookie based session for python WSGI applications

  • Configurable for the following cookie settings
    • Domain
    • Path
    • Secure
    • HttpOnly
    • Expires (timeout)
  • Support for multiple backends
  • HMAC signature to verify cookie has not been tampered with

  • Autosave option which saves anytime a session value is modified

  • Optional Encryption of cookie data using AES

  • Custom timeout per session

Installation

Vishnu is available on PyPi and we recommend installation via pip.

pip install vishnu

The following extra installations also exist which include the desired backend library as a requirement.

pip install vishnu[pymemcache]
pip install vishnu[python-memcached]
pip install vishnu[redis]

If you are working with Google App Engine we recommend installation via pip as a vendored package.

pip install -t lib vishnu

Edit the appengine_config.py file and provide your library directory to the vendor.add() method.

from google.appengine.ext import vendor

vendor.add('lib')

Alternatively download your preferred tagged release and all you should have to include is the vishnu folder.

Configuration

Session Config

The following parameters are available for session configuration.

parameter required default type description
secret yes None string Secret used for HMAC signature, must be at least 32 characters.
cookie_name no vishnu string Name to use for cookie.
encrypt_key no None string Key used to encrypt cookie data, if omitted then data will not be encrypted.
secure no True bool Only send this cookie over SSL
domain no N/A string The domain to set the cookie for, it omitted will use domain cookie was served from.
path no / string The path to set the cookie for, if omitted it will default to /
http_only no True string Only allow cookies access via HTTP/HTTPS
auto_save no False bool Automatically save the session when a value is set.
timeout no N/A integer How long until session/cookie expires, it omitted it will last for the length of the browser session.
backend yes N/A backend See backends configuration

Example of a session configuration.

from vishnu.session import Config
from vishnu.backend import Redis

config = Config(
    secret="your_secret",
    backend=Redis()
)

WSGI Middleware

To use vishnu you must add it as a middleware to your WSGI application.

from vishnu.backend import Redis
from vishnu.middleware import SessionMiddleware
from vishnu.session import Config


my_config = Config(
    secret="your_secret",
    backend=Redis()
)

app = SessionMiddleware(app=wsgi_app, config=my_config)

Backends

Google App Engine (memcache)

from vishnu.backend import GoogleAppEngineMemcache

config = Config(
    secret="your_secret",
    backend=GoogleAppEngineMemcache()
)

Google App Engine (NDB)

from vishnu.backend import GoogleAppEngineNDB

config = Config(
    secret="your_secret",
    backend=GoogleAppEngineNDB()
)

PyMemcache

parameter required default type
host no localhost string
port no 11211 integer
from vishnu.backend import PyMemcache

config = Config(
    secret="your_secret",
    backend=PyMemcache(host="memcache.host", port=11222)
)

PythonMemcached

parameter required default type
host no localhost string
port no 11211 integer
from vishnu.backend import PythonMemcached

config = Config(
    secret="your_secret",
    backend=PythonMemcached()
)

Redis

parameter required default type
host no localhost string
port no 6379 integer
db no 0 integer
from vishnu.backend import Redis

config = Config(
    secret="your_secret",
    backend=Redis(host="redis.host", port=6421, db=0)
)

Setting a Custom Timeout

Each session uses the default timeout specified in your server config but if you want to have particular sessions differ to this you can do the following.

session = vishnu.get_session()
session.timeout = 3600
session.save()

The timeout is in seconds. To set the timeout to expire at the end of this session you can use the vishnu.session.TIMEOUT_SESSION constant.

session = vishnu.get_session()
session.timeout = vishnu.session.TIMEOUT_SESSION
session.save()

Cleaning up Expired Sessions (Google App Engine NDB backend only)

Add the following to a cron handler.

from vishnu.util import gae_ndb_delete_expired_sessions

while not gae_ndb_delete_expired_sessions():
    pass

You can alter the period after expired sessions are deleted by passing a value in seconds as dormant_for. You can also alter the amount of sessions to delete per call using the limit argument.

from vishnu.util import gae_ndb_delete_expired_sessions

while not gae_ndb_delete_expired_sessions(dormant_for=3600, limit=100):
    pass
 
File Type Py Version Uploaded on Size
vishnu-3.0.0-py2.py3-none-any.whl (md5) Python Wheel 2.7 2017-08-27 35KB
vishnu-3.0.0.tar.gz (md5) Source 2017-08-27 18KB