meson

Clojure Client Library for the Mesos HTTP API

meson noun. A functional particle composed of a Mesos deployment and a Mesos HTTP API service bound together by the strongly interacting force of Clojure.

Contents

• About
• Dependencies
• Versions
• Quick Start
• Documentation
• Usage
• License

About ↟

This project is a work in progress.

Meson aims to provide an HTTP-only Clojure client API for Mesos with no dependencies upon the Mesos Java library nor protobufs, thus making installation and dependencies much easier to manage.

Dependencies ↟

• Java
• Mesos 1.3+
  • You need a running Mesos deployment
• lein

Versions ↟

Quick Start ↟

Meson provides some lein commands you can use while developing in the library:

• lein meson mesos start
• lein meson mesos stop
• lein meson mesos restart

These may also be used from the Meson REPL (using the dev profile):

(require '[meson.ops.mesos :as mesos])
(mesos/start-local-docker)
(mesos/stop-local-docker)
(mesos/restart-local-docker)

These will start a Docker container running with locahost ports 5050 and 5051 mapped to those of the running Mesos container.

Documentation ↟

Meson API Reference docs are available here:

• http://clojusc.github.io/meson/

Usage ↟

Provide Framework, Use Default Handlers and Default/Localhost Mesos

Subscribe a framework with default handlers to a localhost Mesos master.

Purpose: Development/testing.

Start up the REPL (and be sure to have a running Mesos deployment), then:

(require '[clojure.core.async :as async]
         '[clojure.pprint :refer [pprint]]
         '[meson.api.scheduler.core :as scheduler])
(def framework-info {:framework-info
                     {:user "user1"
                      :name "a-framework"}})
(def channel (scheduler/subscribe framework-info))

Since subscribe was only called with the framework setup info and didn't also pass a handler function or mesos master URL, it will use the default framework handler (basically just a logging message for each scheduler event) and subscribe to localhost. Any real-world Meson framework will have its own handler, pass it to the subscribe function, and also pass a Mesos master scheduler api URL.

Provide Framework and Handlers, Use Default/Localhost Mesos

Subscribe a framework, providing your own handler functions, to a localhost Mesos master.

Purpose: Development/testing.

• Define your own handler functions as multi-methods. (See meson.api.scheduler.handlers for an example.)
• Same requires and framework definition as previous section.
• Subscribe command is now:

(def channel (scheduler/subscribe framework-info my-handlers))

Provide Framework, Handlers, and Mesos Master

Subscribe a framework, providing your own handler functions, to a remote Mesos master.

Purpose: Production use.

• Define your own handler functions as multi-methods. (See meson.api.scheduler.handlers for an example.)
• Same requires and framework definition as previous section.
• Retrieve the URL to your remote Mesos master scheduler api.
• Subscribe command is now:

(def channel (scheduler/subscribe framework-info my-handlers "https://my-mesos-master.org:5050/api/v1/scheduler"))

Provide Framework, Mesos Master, Use Default Handlers

Subscribe a framework, with default handler functions, to a remote Mesos master.

This is a scenario in which you want to verify you can successfully subscribe to a remote mesos master, but have not written handlers yet.

CAUTION: The default handlers do NOT decline offers. Once subscribed, all offers will go to the framework and wait, preventing other frameworks from getting offers.

Purpose: Development/testing.

• Require an additional meson library. (see code below)
• Same framework definition as previous section.
• Retrieve the URL to your remote Mesos master scheduler api.
• Subscribe command is now:

(require '[clojure.core.async :as async]
         '[clojure.pprint :refer [pprint]]
         '[meson.api.scheduler.core :as scheduler]
         '[meson.api.scheduler.handlers :as scheduler-handlers])
(def channel (scheduler/subscribe framework-info scheduler-handlers/default "https://my-mesos-master.org:5050/api/v1/scheduler"))

Subscription Results

Regardless, a channel is returned in both cases, and that can be interacted with directly in the REPL, for example:

(def result (async/<!! channel))
(pprint result)

Which should give something like:

{:subscribed
 {:framework-id {:value "6919832b-083e-4db5-89ae-a0d1d222510a-0016"},
  :heartbeat-interval-seconds 15.0,
  :master-info
  {:address {:hostname "0414d10a4f36", :ip "172.17.0.2", :port 5050},
   :hostname "0414d10a4f36",
   :id "6919832b-083e-4db5-89ae-a0d1d222510a",
   :ip 33558956,
   :pid "master@172.17.0.2:5050",
   :port 5050,
   :version "1.3.1"}},
 :type :subscribed}

License ↟

Copyright © 2016-2020, Clojure-Aided Enrichment Center

Apache License, Version 2.0.