ketzacoatl

Overview

This gist demonstrates how to run a docker container with nomad, using a wrapper script.

Why would you want to use this?

With the wrapper, we can more easily run the container in the way we need to and without being limited by Nomad's docker driver. For example, while Nomad will have great support for volumes in the future, it has no such support right now, and the driver does not expose a config parameter to tune the volumes mounted in the docker container. This is also a great way to use consul to lookup services before starting your app, or to retrieve credentials from Vault. When running legacy applications with nomad, the wrapper script is the place to put that type of look-up logic.

We use a wrapper script and the raw_exec driver to run the container with the parameters we need.

ketzacoatl

{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE OverloadedStrings #-}

module Main where

import Network.Consul (getSelf, ConsulClient(..), initializeConsulClient, listKeys) 
import qualified Network.Consul.Internal as I

client = initializeConsulClient "localhost" 8500 Nothing

ketzacoatl

import sys
from time import sleep

import consul
import consul_lock
from docker import Client

'''
This is a PoC which uses consul's locking mechanism to ensure only
one instance of the named docker container is running. Requires:

ketzacoatl

{%- set repo_root = '/root/consul-template' %}
{%- set revision = 'v0.10.0' %}

include:
  - golang


consul-template:
  git.latest:
    - name: https://github.com/hashicorp/consul-template