Redis

Overview

Redis (http://redis.io) is an open source, advanced key-value cache and store. It is often referred to as a data structure server since keys can contain strings, hashes, lists, sets, sorted sets, bitmaps and hyperloglogs. In order to achieve its outstanding performance, Redis works with an in-memory dataset that can be written to disk. Redis also supports master-slave asynchronous replication.

Redis can be configured in a master or slave configuration. This charm provides a single stand alone implementation of Redis software supporting the master-slave relationship. Go to the Redis web pages for more information on replication.

Usage

To deploy this charm first bootstrap your Juju environment and issue the following command:

juju deploy redis

Expose the master if you need to contact them for some reason.

juju expose redis

Replication

Redis can be set up with master-slave replication in Juju. This allows the Redis slave to be an exact copy of master server. A master can have multiple slaves.

To set up a master-slave scenario, deploy two services using this charm, one for the master and one the slave server, then relate the two.

juju deploy redis redis1
juju deploy redis redis2
juju add-relation redis1:master redis2:slave

Connecting to the charm

The charm provides a db relation for services wanting to connect to the Redis service. When the relation established the following data is passed to the related units:

• hostname: the Redis server host name;
• port: the port the Redis server is listening to;
• password: the optional authentication password, or an empty string if no authentication is required.

Testing Redis

To test if Redis software is functioning properly, telnet to the Redis private ip address using port 6379. First you need to retrieve the private address of the Redis instance, then you can use juju ssh to connect to that address, for instance::

juju ssh redis/0 telnet `juju run --unit redis/0 "unit-get private-address"` 6379

You can also install the redis-tools package apt-get install redis-tools and connect using the Redis client command:

redis-cli

From there you can issue Redis commands to test that Redis is working as intended.

Development and automated testing.

To create a development environment, obtain a copy of the sources, run make sysdeps to install the required system packages and then make to set up the development virtual environment. At this point, it is possible to run unit and functional tests, including lint checks, by executing make check.

Run make deploy to deploy the local copy of the charm for development purposes on your already bootstrapped environment.

Use make help for further information about available make targets.

Redis Information

• Redis home page
• Redis github bug tracker
• Redis documentation
• Redis mailing list