pyramid_kvs

Some Key Value Store basics for pyramid:

Two KVS are implemented:

memcache
redis

Here are the provides features:

An application cache, shared by every request.

A session manager

A rate limit per session holder

A perl session reader (except you are migrating a perl website,

you probably don't want to use it).

Every of this components are optional, they exists if they are set in the configuration like below. Component settings are written in json.

Cache

The application cache is a new attribute of the session. request.cache if the settings kvs.cache exists. Here are an example of configuration

kvs.cache = {"kvs": "redis",
             "codec": "pickle",
             "kvs_kwargs": {},
             "ttl": 300,
             "key_prefix": "cache::"}

Every kvs, except the type are optional. The example contains every key with their default values for a redis instance. The kvs_kwargs key is passed to the driver to build the client connection.

Session

The session is accessible via "request.session", it's in every pyramid application. This is just an implementation for Key Value Store users.

kvs.session = {"kvs": "redis",
               "key_name": "session_id",
               "session_type": "cookie",
                "ttl": 300,
                "key_prefix": "session::"}

Every kvs, except the type are optional. The example contains every key with their default values for a redis instance.

You can also create a session for an http header like authentication token, it's help to create a cache per user in an API. API don't use cookies.

kvs.session = {"kvs": "redis",
               "key_name": "X-Auth-Token",
               "session_type": "header",
                "ttl": 300,
                "key_prefix": "session::"}

Ratelimit

The ratelimit works only if the kvs.session is used! Ratelimit is per session hold and limit number of http queries in a defined period.

kvs.ratelimit = {"window": 1, "limit": 15}

All keys are optional. The example contains every key with their default values for a redis instance.

If the ratelimit is enabled, every response will be decorated with the following http headers:

X-RateLimit-Limit: max queries in the period.

X-RateLimit-Remaining: current remaining queries in that period.

perlsess

This permit to read a session from a perl that use storable session.

storable: http://search.cpan.org/~ams/Storable-2.45/Storable.pm

Here is an example.

# declare the perlsess
kvs.perlsess = {"type": "memcached"}

Usage:

Declare the addons in the pyramid.includes in your config, then tweak the settings like above.

# development.ini
[app:main]
pyramid.includes =
    pyramid_kvs

# declare the application cache
# except type, every keys are optional
# kvs_kwargs for redis is the parameters of the redis.Redis class
# see: http://redis-py.readthedocs.org/en/latest/
# for memcache, parameters of the memcache.Client class
# https://github.com/linsomniac/python-memcached/blob/master/memcache.py#L160
kvs.cache = {"type": "redis"}

# declare the session
kvs.session = {"type": "redis"}

# Authorize a session holder to do 20 http queries max in 2 seconds.
kvs.ratelimit = {"window": 2, "limit": 20}