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What the hell is it?

Your personal App Engine.

Like GAE?

Sort of. Cocaine is a fast and lightweight multi-language (you can easily write your own language binding) event-driven (also, you can easily write your own event drivers) task-based distributed application engine. Actually, it's better.

Notable features:

  • Apps are defined as a set of tasks, which trigger events in the app engine, which are then processed on a slave pool. Tasks can be servers, time-based jobs, filesystem monitors, etc.
  • Dynamic self-managing slave pools for each app with a rich but simple configuration to scale with the application needs.
  • Data streaming and pipelining.
  • Automatic node discovery and smart peer-to-peer balancing. Note that ZeroMQ already offers built-in fair balancing features which you can use, although they do not consider real node load.
  • Optional resource control via Linux cgroups.
  • Optional secure communications using RSA encryption.
  • Simple modular design to add new languages, task types, storages and slave backends easily.

At the moment, Cocaine supports the following languages and specifications:

  • C++
  • Python
  • [In Development] Perl
  • [In Development] JavaScript

The application tasks can be driven by any of the following drivers:

  • Recurring Timer (multiple jobs can be run if they are not finished in the timer intervals)
  • Drifting Timer (only one job can be run, hence the drift)
  • [In Development] Cron
  • [In Development] Manual Scheduler
  • Filesystem Monitor
  • ZeroMQ Server (Request-Response)
  • [In Development] ZeroMQ Subscriber (Publishing Chain)
  • Native Server (Request-Response + Smart Balancing)
  • ZeroMQ Sink (Request-Publish)
  • [Planned] Native Sink (Request-Publish)
  • [In Development] Raw Socket Server

A motivating example

{
    "type": "python",
    "args": {
        "source": "/path/to/application",
    },
    "engine": {
        "heartbeat-timeout": 60,
        "pool-limit": 20,
        "queue-limit": 5,
        "resource-limits": {
            "cpuset": {
                "cpuset.cpus": "0-3",
                "cpuset.mems": "1",
            }
        }
    },
    "tasks": {
        "aggregate": {
            "type": "recurring-timer",
            "interval": 60000
        },
        "event": {
            "type" : "native-server"
        },
        "spool": {
            "type": "filesystem-monitor",
            "path": "/var/spool/my-app-data"
        }
    }
}

The JSON above is an application manifest, a description of the application you feed into Cocaine for it to be able to host it. In a distributed setup, this manifest will be sent to all the other nodes of the cluster automatically. Apart from this manifest, there is no other configuration needed to start serving the application.

Okay, I want to try it!

Then it's time to read our Wiki for installation instructions, reference manuals and cookies!