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# -*- html -*-
timestamp: Wed 29 Jun 2011 08:42:38 AM PDT
title: in which systems are captured
tags: clojure, seajure, projects
id: 150
content: |-
<p>When working on a project, I try to take care
that <a href="">a
dev environment can be brought up with as little fuss as
possible</a>. This requires some discipline even with simple
programs, but once you get into the realm of <i>systems</i>, more
up-front effort is required for repeatability.</p>
<p>We've all been in the position of being the new hire on the
team. On some teams you're lucky if you can get to actually
running code on your machine in your first week. You think to
yourself that it could surely be simplified, but once you're all
set up there's not a lot of incentive to come back and make it
easy for the next time.</p>
<p>It's easy enough to track language-level
dependencies using
<a href="">Leiningen</a>,
Rubygems, or whatever is standard for your language, but very few
large systems end there. You almost always have further external
dependencies that are best handled by the system-level package
manager, be they databases, message queues, or even your language
runtime itself.</p>
<img src="/i/pond.jpg" alt="discovery park. no reason." />
<p>I've found the best way to make sure this stuff is kept up is to
make it the status quo. At work nearly everyone develops in a VM,
and when a new dependency is needed, instead of everyone having to
hunt down and install it, it just gets added to the setup
script. This reduces redundancy as well as helping to
eliminate <a href="">Works
on My Machine</a> issues.</p>
<p>Recently I've found <a href="">Vagrant</a> to
be a really helpful tool for streamlining this process even
further. Before I was using
raw <a href="">VirtualBox</a>, which was
all right for launching fresh VMs, though the interface was always
a little awkward. Vagrant streamlines this greatly, making it
trivial to configure, suspend, and rebuild VMs. It also helps keep
the configuration of the VM alongside the project for which it's
<p>Vagrant allows you to provision new VMs
with <a href="">Chef</a>. While
this is pretty handy if you've already got recipes written, it's a
bit intimidating as the mental model needed to operate Chef is
quite baroque. But it's easy enough to bypass Chef and
provide <a href="">an
arbitrary shell script</a> as a provisioner. You need to take a
bit of care to ensure the script is idempotent as it's much more
useful if you can re-run it whenever the dependencies change, but
it's a great way to get started.</p>
<p>There are a few gotchas. Vagrant is rather particular about what
version of Virtualbox (and the VBox extension pack) you use, and
reinstalling Virtualbox only makes it confused. The OSS edition
isn't supported, but thankfully an apt repository is
<pre style="font-size: 80%;">$ sudo apt-add-repository "deb $(lsb_release -cs) contrib"
$ wget -q -O - | sudo apt-key add -
$ sudo apt-get update && sudo apt-get install virtualbox-4.0
$ sudo gem install vagrant</pre>
<p>On a related note, I've had had a couple people ask what a good
project to get started with Clojure web programming would be. The
most widely-used Clojure web app that I know of
is <a href="">Clojars</a>, the community
repository. But it's been pretty dormant recently; there are
<a href="">plenty
of great features</a> just waiting to be implemented, but getting
it set up is hard work given all the moving parts.</p>
<p>Vagrant is perfect for smoothing this over. I've got
a <a href="">vagrant
branch of clojars</a> that makes it as simple as <kbd>vagrant
up</kbd> (modulo a small issue with the nailgun scp server I'm
still working out). So this should allow folks to contribute to
the codebase more easily.</p>
<p>I've also helped out
with <a href="">Justin
Lilly's Clojure/Emacs environment</a> which provides a
fully-configured Emacs 24 install intended to help facilitate our
<a href="">Seajure hackfests</a>. Give
it a try if you've had trouble configuring Emacs for Clojure
hacking. And feel free to crib from these setups for automating
your own projects.</p>
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