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<title>Zk | 2015-04-06-dogfooding-1</title>
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<h1>Zk | 2015-04-06-dogfooding-1</h1>
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<p>type: post
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date: 2015-04-06
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slug: dogfooding-1
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title: Dogfooding - Pt. 1</p>
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<hr />
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<p>I work for <a href="http://canonical.com">Canonical, Ltd</a>, a company focused primarily
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on open source software, best known for their operating system,
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<a href="http://ubuntu.com">Ubuntu</a>, a distribution of Linux focused on both the ease of
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desktop use, as well as a seamless experience across desktop, server, mobile,
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and TV. That’s not all that we make, though, and our umbrella of products and
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services stretches across several sectors of the software market.</p>
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<p>I am on the Juju UI team. <a href="http://jujucharms.com">Juju</a> is a dev-ops solution
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that allows packaging server software into Juju Charms, which act as biased
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installations of software that are built by people who know how that software
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can best be deployed. For instance, the <a href="https://jujucharms.com/wordpress/">Wordpress
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charm</a> encapsulates an installation of
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Wordpress, just as the <a href="https://jujucharms.com/mysql/">MySQL charm</a> packages an
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installation of MySQL, such that, if you have a Juju environment up and running,
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you can simply run:</p>
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<p _="%" endhighlight="endhighlight">{% highlight bash %}
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juju deploy wordpress
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juju deploy mysql
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juju add-relation wordpress mysql
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juju expose wordpress</p>
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<p>and wind up with a proper installation of Wordpress talking to a proper
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installation of MySQL in the cloud of your choice.</p>
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<p>I work on more than just the projects I have at Canonical, however. I’ve bought
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wholeheartedly into both the ethos and implementation of open source software,
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and so I work on releasing as much of my own free-time projects as open source
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as possible. Lately, the project that has been taking up much of my weekends
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and evenings has been an exploration of <a href="http://golang.org">Go</a>, a programming
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language by Google with a focus on simplicity and concurrency. I chose this
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language for this task because Juju itself, along with many of its tools, are
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written in Go.</p>
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<p>The project I’ve been working on,
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<a href="https://github.com/warren-community/warren">Warren</a>, is a pretty simple bit of
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web software that allows publishing of entities of various types - from blog
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posts to pictures and so on - and linking of those entities into a web of
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content. Or, rather, those are my hopes for it; it’s still in its early stages.
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I’ve learned a lot about Go, many Go web utilities such as
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<a href="http://martini.codegangsta.io/">Martini</a>,
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<a href="https://github.com/codegangsta/gin">Gin</a>, and
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<a href="http://www.gorillatoolkit.org/">Gorilla</a>, testing in Go using
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<a href="http://goconvey.co/">GoConvey</a>, as well as the services that back Warren up
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such as Mongo and ElasticSearch.</p>
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<p>Writing a web app such as this, it was a natural solution to charm Warren so
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that I could manage it, along with its backing services, in a scalable fashion
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on any of the clouds that Juju supports.</p>
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<h2 id="what-i-did">What I Did</h2>
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<p>The work that I’ve done to date consists of two parts beyond Warren itself: the
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<a href="https://github.com/warren-community/warren-charm">Warren charm</a> and the <a href="https://github.com/warren-community/warren-bundle">Warren
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bundle</a>. Whereas charms
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describe the way in which a singal service is deployed, bundles are groups of
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charms that work together as a group of services providing a particular
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functionality. For instance, the Warren bundle includes Warren, Mongo,
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ElasticSearch, and haproxy for load balancing.</p>
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<h3 id="the-warren-charm">The Warren charm</h3>
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<p>I went with the idea of a “thin” charm. This means that the charm itself does
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not contain any of the source code or binaries required for building Warren
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itself. This is as opposed to “thick” (sometimes referred to as “fat”) charms,
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which contain a binary, a zip of source code, or some other means of deploying
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the service without reaching out to some external location. There are a few
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advantages and disadvantages to each:</p>
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<h4 id="thin-charms">Thin charms</h4>
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<ul>
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<li>Advantages:<ul>
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<li>Change to the code of the services does not mean change to the code of the
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charm.</li>
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<li>Charms are much smaller, and thus are uploaded to the environment fairly
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quickly.</li>
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</ul>
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</li>
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<li>Disadvantages:<ul>
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<li>Services will require access to wherever the source or binary to be
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deployed. In Warren, that’s the GitHub repository, but it may be a PPA or
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other source of packages. In some clouds, access such as this may be
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heavily restricted.</li>
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<li>Since the code must be fetched, potentially built, and then installed,
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some of the speed gains for not having to upload the charm are lost.</li>
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</ul>
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</li>
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</ul>
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<h4 id="thick-charms">Thick charms</h4>
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<ul>
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<li>Advantages:<ul>
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<li>You can be guaranteed that the code that is in the charm is the only code
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that will be deployed in the service without having to use any
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work-arounds for pinning fetched source at a revision or tag.</li>
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<li>Deployment is usually fairly easy and fast, since you don’t have to worry
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about fetching source and building, and since no external sources are
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required, you can safely deploy behind a strict firewall.</li>
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</ul>
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</li>
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<li>Disadvantages:<ul>
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<li>Thick charms are rather large and may take a bit of time to actually
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deploy, since the charm will need to be uploaded to the environment either
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from your local machine or from the charmstore.</li>
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<li>Changes in your codebase will not show up when a new charm is deployed,
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since the code exists at one particular revision - this means that
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emergency bug fixes in your code mean an emergency charm release
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containing that fix, and a charm upgrade.</li>
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</ul>
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</li>
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</ul>
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<p>For Warren, I went with a thin charm for a few reasons:</p>
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<ul>
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<li>I live in the mountains, where Internet connectivity is limited to microwave
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line-of-sight of okay-but-not-great speeds. I didn’t want to have to
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re-upload the charm to EC2 every time I made a fix to it (charm developing
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being a particularly iterative process). Once the charm winds up in the
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store, should it wind up there, this will not be as much of a concern.</li>
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<li>I want to iterate fairly quickly on Warren, if it winds up going somewhere. I
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want to be able to iterate on Warren much more than I want to be able to
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iterate on the Warren charm, however, so I’d rather spend an initial
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investment allowing a means of upgrading the Warren source in a deployed
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instance of Warren through a configuration change (more on this later) than
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have a repeated time sink involved in building a new version of the charm.</li>
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</ul>
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<p>In the end, the wins that thick charms get me are outweighed by the wins
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involved in thin charms.</p>
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<h3 id="the-warren-bundle">The Warren bundle</h3>
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<p><img alt="Warren in the Juju GUI" src="/assets/tech/dogfooding-1.png" /></p>
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<p>The Juju GUI is the project that I have spent the most time with during my time
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at Canonical. I started out on the GUI, and continue to contribute to it even
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as focus has shifted to other aspects of the various user interfaces to Juju.
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One of the things that I like about it is that it’s really easy to see just how
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your entire environment works and fits together. In the instance above, you can
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see haproxy exposed, which leads to Warren, which depends on Mongo and
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ElasticSearch. There’s a flow of traffic indicated in the diagram - a request
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to the exposed bit, which is proxied to Warren, which may make a request of
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either Mongo, ElasticSearch, or both.</p>
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<p>Another benefit of the Juju GUI is that it allows you to export the current
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environment in the format of a <a href="https://jujucharms.com/docs/1.20/charms-bundles">Juju
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bundle</a>, which is a repeatable
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representation of an environment. These bundles can then be reimported with the
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GUI or with another of our tools, Juju Quickstart, which allows building and
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managing Juju environments from the command line.</p>
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<p>In this case, I created and exported my Warren bundle, but am not yet able to
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utilize it. This is because the Warren charm does not yet live in the Juju
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charmstore - it’s only deployed locally - and bundles do not support local
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charms yet. For now, though, I’m happy to have the bundle here as a reference
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to use when deploying Warren to a cloud.</p>
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<h2 id="the-good">The Good</h2>
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<p>My list of good things from this post will probably just read about the
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advantages of using Juju. Once I had the charm up and running, it was
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astoundingly easy to repeat the process: simply <code>juju deploy
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local:trusty/warren-charm</code> from my charm repository. I have to say, there’s no
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beating that. In the past, I’ve deployed and managed just about every one of my
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projects by hand, and the lack of repeatability led to a ton of external cruft.
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Deployment checklists, extended QA times, slower iterations, and so on. I think
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that Juju helps alleviate all of these to some extent.</p>
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<p>Additionally, in writing and testing the charm, I found all of the weak spots in
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my code that weren’t evident from a development environment. For instance, I
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had relied on several hacks and shortcuts supplied by the libraries I was using
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which, while they looked elegant, were not good solutions for a repeatable
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testing environment or a production environment. For instance, I relied on
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defaults for hosting static files and templates. While this made my code look
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clean and simple, it was not repeatable because there were no guarantees where
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those assets would be stored. Once I charmed Warren, that became evident, and I
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found ways to create a robust means of dealing with these problems that was both
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elegant, and non-magical.</p>
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<h2 id="the-bad">The Bad</h2>
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<p>Docs.</p>
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<p>I found the documentation around the python Charm Helpers, a package used for
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building and supporting charms, to be quite lacking. It feels as though new
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features were implemented in code while the documentation had not yet been fully
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written; what docs are there read as though the user should already understand
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how to use the package.</p>
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<p>As a developer, I’m well aware of this pattern, and definitely guilty of it
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myself. Even so, I was left spinning my wheels for days as I tried to charm up
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Warren. I’ve helped with the charming of several different packages that we use
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within the company, but none of them use the new, undocumented features of charm
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helpers.</p>
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<p>In the end, I wound up working off the old style of creating a python based
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charm - that is, rather than utilizing the <a href="http://pythonhosted.org/charmhelpers/examples/services.html">service
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framework</a> included
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with charm helpers, I created methods that were decorated as hooks, which were
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called simply whenever one of those hooks was fired. This is the style I’ve
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most commonly seen in the charms hosted in the charmstore, and while it does
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work, I get the impression that this newer services framework is much more
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elegant and easy to use. Easy to use once, that is, you understand <em>how</em>.</p>
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<p>It just so happens, though, that the task that I’ve given myself over the next
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few months of free-project time at work is to help improve the documentation of
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the products and services that we have, whether that’s code-side in the form of
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docstrings, wider documentation included with the projects, tutorials, or
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videos. Indeed, that’s much of the purpose behind these dogfooding posts! So
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I’ll be working just has hard as the other teams, I hope, to help document Juju
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and how it can be used for managing cloud deployments.</p>
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<h2 id="whats-next">What’s next</h2>
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<p>Next, I’d like to talk about more specifics about how the Warren charm works and
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the services with which it’s deployed. I hope to make this at least a short
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series, if not an account of my ongoing adventures with dogfooding Juju for my
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own purposes.</p>
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</article>
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