Herdis

Herdis is a simplistic Redis cluster manager based on Redis Presharding described in antirez blog.

Installation

Ruby

We use Ruby 1.9.3.

To install and run on your local machine use RVM. For Mac machines make sure you compile with gcc-4.2 (because the compiler from Xcode doesn't compile Ruby 1.9.3 properly). Download and install gcc from https://github.com/kennethreitz/osx-gcc-installer 

$ gem install rvm
$ rvm install 1.9.3

And for Macs

$ rvm install 1.9.3 --with-gcc=gcc-4.2

Rubygems

Use Bundler to install the gems needed by Herdis

$ bundle install

Redis

Herdis naturally needs Redis to run. Install it and put redis-server in your $PATH.

Running

The bin/herdis script runs a Goliath server with standard Goliath parameters such as -p for port selection, -s for logging to STDOUT, -v for verbose logging etc.

The server also uses a set of ENV variables to control its configuration:

  • SHEPHERD_FIRST_PORT for the first port to run Redis instances on. Defaults to 9080.
  • SHEPHERD_DIR for the directory to put Redis dumps and pidfiles in. Defaults to $HOME/.herdis.
  • SHEPHERD_ID for the id of the server to start. Defaults to a random string.
  • SHEPHERD_INMEMORY to run a server managing only non-persistent Redis instances. Defaults to false
  • SHEPHERD_REDUNDANCY to define number of backups to maintain of each shard. Defaults to 2.
  • SHEPHERD_CONNECT_TO to define another server to connect to on startup. Defaults to nil.

To actually start the server, simply

$ bin/herdis

Using

To use it you require 'herdis/client' and then instantiate a Herdis::Client which will act just like a Redis::Distributed.

require 'herdis/client'

client = Herdis::Client.new("http://localhost:9000")
client.set("test", "value")
raise "this should work, for example" unless client.get("test") == "value"

If you have a cluster of herdis nodes, you can give all their addresses to the new Herdis::Client when you start it (Herdis::Client.new(url1, url2, url3... urln)), that way it will keep trying until it finds one that works (if you want to be able to restart your clients even if the cluster is currently maimed).

Test suite

$ rake

Console

To run an eventmachine-friendly console to test your servers from IRB

$ bundle exec em-console