[web2py] Redis cache and session

[Ralo Tannahill]

I have tried to make some tests using redis to store cache and sessions but 
there is no module "redis".
I am using Version 2.2.1 (2012-10-21 16:57:04) stable, on CENTOS 6 and 
python 2.6.

In gluon.contrib I have redis_cache.py and redis_session.py (both have the 
same "import redis"), but ther is no module named "redis"
>From python shell, typing the import statements from the online book:
>>> from gluon.contrib.redis import RedisCache
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: No module named redis

>>> from gluon.contrib.redis_session import RedisSession
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "gluon/contrib/redis_session.py", line 5, in <module>
    import redis
ImportError: No module named redis

I have browsed the contents of gluon/contrib in Github and see the same 
files.
The support of redis depends on an external module? Should I install a 
redis-client for python as a "redis" module?

Thanks in advance, kind regards

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