Installation

If you are not using pip yet. Install it and while you are at it consider using virtualenv too.

$ pip install cherrys

redis-py and CherryPy are required dependencies hence will be installed if necessary.

We recommend installing hiredis-py (a faster parser) as well.

$ pip install hiredis

Usage (and abusage)

To tell CherryPy which backend to use, we need to specify the storage_type for the sessions tool. You may want to read more about CherryPy configuration.

tools.sessions.storage_type : 'redis'

But CherryPy doesn’t know Redis. Hence the first thing we need to do is add the cherrys RedisSession class to cherrypy.lib.sessions.

import cherrys
cherrypy.lib.sessions.RedisSession = cherrys.RedisSession

It is that simple!

Config dictionary

There are a few optional parameters you can set:

• host [127.0.0.1] (when is_sentinel this is host for sentinel service)

• port [6379] (when is_sentinel this is port for sentinel service)

• ssl [False] (for both sentinel and redis)

• db [0]

• prefix [“”] (prepended to session id if given; useful when ACLs are enabled)

• user [None] (for old version of authentication can be set to empty string)

• password [None]

• lock_timeout [None] (None, or time in seconds until session lock expires)

• url [None] (alternative to host/port/ssl/db/user/password combination)

Sentinel-related additional (optional) parameters:

• is_sentinel [False]

• sentinel_pass [None]

• sentinel_service [None]

• tls_skip_verify [False]

A full config dictionary to activate Redis backed sessions would look like this.

config = {
    'tools.sessions.on' : True,
    'tools.sessions.storage_type' : 'redis',

    'tools.sessions.host': REDIS_HOST,
    'tools.sessions.port': REDIS_PORT,

    'tools.sessions.db': REDIS_DB,
    'tools.sessions.prefix': REDIS_PREFIX,
    'tools.sessions.user': REDIS_USER,
    'tools.sessions.password': REDIS_PASS,
    'tools.sessions.lock_timeout: LOCK_TIME_SECONDS,
}

A full config dictionary to activate RedisSentinelSSL backed sessions would look like this.

config = {
    'tools.sessions.on' : True,
    'tools.sessions.storage_type' : 'redis',

    'tools.sessions.host': REDIS_HOST,
    'tools.sessions.port': REDIS_PORT,
    'tools.sessions.ssl': True,

    'tools.sessions.db': REDIS_DB,
    'tools.sessions.prefix': REDIS_PREFIX,
    'tools.sessions.user': REDIS_USER,
    'tools.sessions.password': REDIS_PASS,
    'tools.sessions.lock_timeout: LOCK_TIME_SECONDS,

    'tools.sessions.is_sentinel': True,
    'tools.sessions.sentinel_pass': REDIS_SENTINEL_PASS,
    'tools.sessions.sentinel_service': REDIS_SENTINEL_SERVICENAME,
    'tools.sessions.tls_skip_verify': True,
}

Configuration via redis URL

As a shortcut a URL to the redis server can be provided as well.

import cherrys
config = {
    'tools.sessions.on' : True,
    # next setting removes the need for initializing `cherrypy.lib.sessions.RedisSession' above:
    'tools.sessions.storage_class' : cherrys.RedisSession,
    'tools.sessions.url': 'redis://your-name:your-pwd@redis-server:6379/2'
}

The number at the end of the URL (“2”) denotes the redis database to be used.

Running unittests

Unittests require a running redis-server on localhost:6379 setup without any authentication in place.

Then install pytest into your current virtualenv and start it from your command line:

$ pip install pytest
$ pytest