Tornado – Redis

As defined on Redis website, it is an open source, advanced key-value store. It is often referred to as a data structure server since keys can contain strings, hashes, lists among others. It’s similar to say memcached library in the sense that it ia an in memory key/value pair but persistent on disk.. Redis has gained importance as a NoSQL option for web development because of its speed (GET and SET operations in the range of 100,000 per seconds). This post is about including Redis in Tornado for web development.

Let’s start with installing Redis-server

ubuntu@ubuntu:~/tornado-2.2$ sudo apt-get install redis-server
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages were automatically installed and are no longer required:
  libtext-glob-perl libcompress-bzip2-perl libparams-util-perl libfile-chmod-perl libdata-compare-perl libfile-pushd-perl libfile-which-perl libcpan-inject-perl
  libfile-find-rule-perl libcpan-checksums-perl libnumber-compare-perl
Use 'apt-get autoremove' to remove them.
The following NEW packages will be installed:
0 upgraded, 1 newly installed, 0 to remove and 171 not upgraded.
Need to get 80.8kB of archives.
After this operation, 283kB of additional disk space will be used.
Get:1 lucid/universe redis-server 2:1.2.0-1 [80.8kB]
Fetched 80.8kB in 2s (27.3kB/s) 
Selecting previously deselected package redis-server.
(Reading database ... 138423 files and directories currently installed.)
Unpacking redis-server (from .../redis-server_2%3a1.2.0-1_i386.deb) ...
Processing triggers for man-db ...
Processing triggers for ureadahead ...
Setting up redis-server (2:1.2.0-1) ...
Starting redis-server: redis-server.


ubuntu@ubuntu:~/tornado-2.2$ ps aux | grep redis
redis    19104  0.0  0.1   2284   716 ?        Ss   21:23   0:00 /usr/bin/redis-server /etc/redis/redis.conf

Python client library for redis

ubuntu@ubuntu:~/tornado-2.2$ sudo pip install redis
Downloading/unpacking redis
  Downloading redis-2.6.2.tar.gz
  Running egg_info for package redis
Installing collected packages: redis
  Running install for redis
Successfully installed redis


With redis installed, lets go to an example where Redis meets Tornado. In the example below,

  • When the web server is started, redis server is initialized with key-value pairs of username and password (password is md5 hash of username in hex format) for users ‘bob’ and ‘clara’.
  • On browsing to http://localhost:8888/login and POSTing the username and password details to Tornado web server, authentication of details happen from redis server.
  • Relevant message for successful/unsuccessful attempt is render on user’s browser

Redis Example
<form action="/login" method="post">
Username: <input type="text" name="username">
Password: <input type="text" name="password">
<input type="submit" value="Submit">

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import tornado.web
import redis
from hashlib import md5
class Login(tornado.web.RequestHandler):
def initialize(self):
## Initialize redis
self.r = redis.Redis("localhost")
## Add users
self.r.sadd("users", 'bob')
self.r.set('bob', md5('bob').hexdigest())
self.r.sadd("users", 'bob')
self.r.set('clara', md5('clara').hexdigest())
def get(self):
def post(self):
username = self.get_argument("username")
password = self.get_argument("password")
if self.r.sismember("users", username):
if self.r.get(username) == password:
self.write("Login successful!")
self.write("Login Unsuccesful..")
application = tornado.web.Application([
(r"/login", Login)],
if __name__ == '__main__':

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