redis-load-scripts

Naive script loader that allows require() from lua scripts in redis

What?

Let's say you have two lua files:

-- sayHi.lua
-- this file returns a function which says hello
return function(who)
  print('Hello ' .. who)
end


-- main.lua
-- this file uses sayHi.lua to print Hello world:
local sayHi = require('sayHi')
sayHi('world')

If we attempt to run main.lua from redis, we will get an error:

> redis-cli EVAL "$(cat main.lua)" 0

(error) ERR Error running script (call to XXX):
@enable_strict_lua:15: user_script:1: Script attempted to access unexisting
global variable 'require'

To make it work, we need to tell redis what is sayHi. Enter redis-load-scripts.

> redis-cli EVAL "$(redis-load-scripts main)" 0
(nil)

This will print "Hello world" in redis, as expected.

How?

If we run example above:

redis-load-scripts main

The output will be:

local _REDIS_SCRIPT = {}

_REDIS_SCRIPT["main"] = function()
  local sayHi = _REDIS_SCRIPT["sayHi"]()
  sayHi('world')
end

_REDIS_SCRIPT["sayHi"] = function()
  return function(who)
    print('Hello ' .. who)
  end
end

return _REDIS_SCRIPT["main"]()

As you can see, the script has resolved all require calls to actual files, and stored them into shared lua table _REDIS_SCRIPT with one twist. Instead of

require("sayHi")

The script printed:

_REDIS_SCRIPT["sayHi"]

This helps redis resolve actual code, and helps developers to reuse their bits of code in large code bases.

usage

To use it from node:

// This command will load `main.lua` file that sits in the `luaPathConfig`
// folder.
var compiled = loadScripts('main', luaPathConfig);

// `compiled` is now a script with all requires resolved

To use it from command line, make sure you've installed it:

npm install -g redis-load-scripts

and then call

redis-load-scripts

license

MIT