RedisGears-2.0

A Redis module that allows running a JS functions inside the Redis processes. The JS code is execute use V8 JS engine.

Notice, RedisGears 2.0 is still under active development and not yet GA, the API might (and probably) change at the final GA version.

Run Using Docker

docker run -p 6379:6379 redislabs/redisgears:edge

Build

With Docker

Run the following on the main directory:

> docker build -t redisgears2 .

Then run the built image:

> docker run -p 6379:6379 redisgears2

From Source

See the build page for more information.

Getting started

Run JS code

The API expose by the module is very similar to the way Redis Functions is working. Lets write a simple hello world RedisGears function that return the string hello world:

#!js name=lib

redis.registerFunction('hello_world', function(){
    return 'hello_world';
});

The first line indicates the engine to use (js) and the library name (lib). The rest is the library code.

Assuming we put the following code on a file lib.js, we can register our function on RedisGears using TFUNCTION LOAD command:

> redis-cli -x TFUNCTION LOAD < ./lib.js
OK

And now we can execute our function using TFCALL command, the command gets the library name and the function name:

> redis-cli TFCALL lib hello_world 0
"hello_world"

Notice that TFCALL command arguments is very close to Redis FCALL command, the only difference is that on RedisGears the command also gets the library name. The 0 represent the number of keys that will follow (which in our case is 0).

Calling Redis Commands Inside our Gears Function

It is possible to call Redis commands inside our gears function. The function gets as first argument a client object that allows interaction with Redis using call function. The following example executes a simple PING command and return the result:

#!js name=lib

redis.registerFunction('my_ping', function(client){
    return client.call('ping');
});

If we will try to send it to our running Redis instance, we will get the following error:

> redis-cli -x TFUNCTION LOAD < ./lib.js
(error) Library lib already exists

We get the error because the library with the same name already exists, we can use the REPLACE argument to replace the library with the new code:

> redis-cli -x TFUNCTION LOAD UPGRADE < ./lib.js
OK

And now we can invoke my_ping using TFCALL :

> redis-cli TFCALL lib my_ping 0
"PONG"

zalenskiSofteq/RedisGears