criteo/mesos-modules-ruby

A simple way to use ruby script as mesos modules

Mesos Modules Ruby

This repository is a collection of experimental mesos modules to call ruby scripts implementing hooks.

This project is not battle-tested, use it at your own risk.

Build Instructions

    $ export MESOS_BUILD_DIR=[ directory where Mesos was BUILT, e.g. ~/repos/mesos/build ]
    $ mkdir build
    $ cd build
    $ cmake ..
    $ make
    $ ./test_rmodules ../tests/mesos_modules.rb

Scripting Documentation

Example available in ./tests/mesos_modules.rb

Ruby based Mesos Hook

RubyHook is currently expecting the following API from the attached Ruby script:

    def slaveRunTaskLabelDecorator taskinfo
        ...             # read and modify taskinfo fields or
        ...             # taskinfo sub-classes, esp. Labels
        return taskinfo # mandatory!
    end
    
    def slaveRemoveExecutorHook execinfo
        ...
        # no return value
    end

Both taskinfo and execinfo are hashes filled from equivalent C++ classes. For instance, you can get the name of a task with taskinfo["name"] and access the labels kv-pairs through taskinfo["labels"] as a string-string hash.

Ruby based Mesos Isolator

Current implemenation supports the prepare and cleanup callback of the mesos isolator For details on the Isolator interface, please check directly the source code: https://github.com/apache/mesos/blob/master/include/mesos/slave/isolator.hpp

  def isolator_prepare params
    # Params contains the container_id, user,
    # and environment (pre-launch w/o for example the actual mesos-slave inject environment!)

    return {"pre_exec_commands" => [{"value" => "touch /tmp/rb_isolator"}]} # pre exec commands
  end

  def isolator_cleanup params
    # params: hash containing a container_id
  end

Deployement & Configuration

This library supports a single source Ruby script, for both supported module interfaces: hook and isolation. The hook and isolation modules both supports the script_path parameter, and shall be pointing to the same script. The library will, on purpose, only take into account the first script_path processed.

This is done on purpose to make it explicit that all modules (hook and isolator) will run in the same ruby context (single vm/process).

Example of json configuration file in examples sub-folder. Don't forget to add com_criteo_mesos_RubyIsolator to the list of slave's activated isolators (--isolation="...,com_criteo_mesos_RubyIsolator")