Wolverine

Wolverine is a simple library to allow you to manage and run redis server-side lua scripts from a rails app, or other ruby code.

Redis versions 2.6 and up allow lua scripts to be run on the server that execute atomically and very quickly.

Wolverine is a wrapper around that functionality, to package it up in a format more familiar to a Rails codebase.

How do I use it?

1. Make sure you have redis 2.6 or higher installed.

redis-server -v

2. Add wolverine to your Gemfile:

gem 'wolverine'

3. Add your lua scripts to app/wolverine:

-- app/wolverine/util/mexists.lua
local exists = {}
local existence
for _, key in ipairs(KEYS) do
  table.insert(exists, redis.call('exists', key))
end
return exists

4. Call wolverine from your code:

Wolverine.util.mexists(['key1', 'key2', 'key3']) #=> [0, 1, 0]

Or

Wolverine.util.mexists(:keys => ['key1', 'key2', 'key3']) #=> [0, 1, 0]

Methods are available on Wolverine paralleling the directory structure of wolverine's script_path.

Nested Lua Scripts

For lua scripts with shared code, Wolverine supports ERB style templating.

If your app has lua scripts at

• app/wolverine/do_something.lua
• app/wolverine/do_something_else.lua

that both have shared lua code, you can factor it out into a lua "partial":

• app/wolverine/shared/_common.lua

-- app/wolverine/shared/_common.lua
local function complex_redis_command(key, value)
  local dict = {}
  dict[key] = value
end

-- app/wolverine/do_something.lua
<%= include_partial 'shared/_common.lua' %>
complex_redis_command("foo", "bar")
return true

-- app/wolverine/do_something_else.lua
<%= include_partial 'shared/_common.lua' %>
complex_redis_command("bar", "baz")
return false

• partials are loaded relative to the Wolverine.config.script_path location
• partials can be protected by adding an underscore (eg. shared/_common.lua). This disallows EVAL access through Wolverine.shared._common

Configuration

Available configuration options:

• Wolverine.config.redis (default Redis.new)
• Wolverine.config.script_path (default Rails.root + 'app/wolverine')
• Wolverine.config.instrumentation (default none)

If you want to override one or more of these, doing so in an initializer is recommended but not required. See the full documentation for more details.

More information

For more information on scripting redis with lua, refer to redis' excellent documentation: http://redis.io/commands/eval