Welcome back to our Puppet and Git 200-series classes. With r10k installed and configured, today we can focus on workflows. The first workflow is for a new module, either a brand new module you are creating or simply a “new to you” module, such as importing more modules from the Forge. In our classrom, we will add a single module from the forge and update the base module to make use of it. This will give us a good understanding of the workflow for r10k.

Workflow To Add A New Module

The first step in our workflow is to decided on a module to add to our setup. If you have a particular module you want to use, feel free to substitute it below. I’ve chosen saz-motd, a very simple module that is visible when installed, but will not have a material impact on your nodes. We can see right now that there is no message of the day, so we’ll know when we’re done:

[root@puppet ~]# cat /etc/motd
[root@puppet ~]#

Note: We’ll add our module to a feature branch below. It’s a simple module, so this is fine. More complex modules, such as those that include additional facts and functions, should always be installed on the master first to ensure the plugins are synchronized, which means adding them to production. This was discussed on IRC so I don’t have a link to documentation to show how this works; this is the closest I could find. I’ll mention it again when we install such a module, but I wanted to mention it in case the module you chose provides custom facts/functions.

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Welcome back! In our 201 class, we installed r10k, but we still haven’t used it. There’s two tasks we need to complete. First, the existing repo is incompatible with r10k’s dynamic management of modules, so we’ll convert its contents to the proper format. Once that is done, we can deploy dynamic environments using r10k.

Convert existing repo

Check out a clone of the existing puppet repo, rnelson0/puppet-tutorial. As mentioned previously, you can do this on the puppet master, as I will do, or you can perform it on another machine. If you’re on the master, you want to clone the repo into a different directory. After cloning it, check out a new branch called production:

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I know you’re probably anxious to get started with managing your infrastructure, but we’re going to stay distracted by Git for a little longer. In the 100 series, we saw some examples of how to migrate your manifests and modules into Git and how to make changes to your manifests through branches. The setup is a little primitive, but acceptable for a lab – everything is is either done by root or involves pushing changes as a user and pulling them as root, and changes are tested in production. I’d like to introduce you to a tool called r10k that will help us create dynamic branches for testing and decouple our workflow from direct access to the puppet master. In this 201 class, we’ll work on the first half by migrating our existing repo structure into r10k.

Review and Setup

If we review the puppet-tutorial repo’s master branch, we have a standard directory layout that you should be somewhat familiar with now:

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In Puppet and Git 101, we looked at how to add our existing puppet code to our repo. We’re going to take a quick look at how to create a branch, add some code, commit it, and push it to our repo.

Create a Branch

For lack of something significant to do right now, we’ll add a notify command to the node definition for puppet.nelson.va. To do so, we will checkout a new branch called, appropriately, notify. You can call your branches whatever you want, I suggest you simply be consistent in your naming scheme. At work, I use a combination of a ticket number and a one or two word description of the feature, separated by hyphens. Normally our branch is going to be short lived and only exist locally (we’re going to make an exception to that for demo purposes), so it would be a moot, but it’s still a good habit to be in.

[root@puppet puppet]# git branch
* master
[root@puppet puppet]# git checkout -b notify
Switched to a new branch 'notify'
[root@puppet puppet]# git branch
  master
* notify

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Now that we’ve set up a puppet master and puppetized template, created a sample manifest, and started creating our own module, it’s time to take a few moments to talk about using Puppet with a version control systems (VCS). This article is mainly for those new to VCS at all or new to Git; those very familiar will want to skim or skip this article entirely.

What we have done so far is adding and removing a few lines in a couple files, and we’ve treated it as such. But it’s so much more. Writing code that represents an infrastructure state and using software to implement it is the root of two important IT movements: DevOps and the Software Defined Data Center (SDDC). You write code, puppet creates the infrastructure according to your instructions. Need something changed? Update your code, puppet takes care of the rest. What if you mess up? That’s where version control comes into play.

Version control, among other benefits, gives us the option to look at our code at points in time and to track changes over time, usually with some level of audit detail. If I make a change today and everything runs fine for a few days before blowing up, I can use version control to track the changes made to see if someone else made a change in the interval or perhaps go back to the version prior to my change. Without version control, you have no functional ability to audit your changes and revert the state of your code to a particular point in time.

There are a number of different version control systems that you can use. Subversion has been a popular VCS, though it has some long standing limitations and has been losing favor for a while. Git is a newer distributed version control system (DVCS) that has gained massive popularity by addressing some of the limitations of non-distributed VCSes and encouraging public development via Github.com and other cloud DVCS providers. We’re going to focus on Git due to its popularity, the plethora of examples of Puppet + Git available on the internet, and the ability to leverage Github.

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