This is the first in what will be a series of posts on how to establish a continuous delivery pipeline. The eventual goal is to have an app that we can push out into production anytime we like, safely and with little effort. But we’re going to start small and proceed incrementally, which is the best way to undertake this sort of effort.

In this post we’ll start by establishing continuous integration for an arbitrary Java/Maven-based open source library project. It shouldn’t take more than an afternoon to do this more or less from scratch if you’re reasonably familiar with the technologies in question, except for the part where we have to get a Maven repo. We have to wait for Sonatype to approve the repo, but they’re pretty fast about it.

I set this up for an open source library project I’m doing called Kite. The details of the project itself aren’t important for this exercise, but the open source library part is:

• Libraries (as opposed to apps) are easier to deal with, because deployment is just a matter of getting the binary into a Maven repo, as opposed to getting it running on a live server.
• Open source means that we can get a bunch of infrastructure freebies.

Here’s what it will look like at the end of this post:

So if you have an open source library you’ve been wanting to develop, now’s the time to get started!

Find a place to host your project sources

The right host depends on which SCM you prefer. If you like Git, then GitHub and Bitbucket are two obvious (free) choices. Bitbucket supports Mercurial as well, and it supports not just free public repos like GitHub, but free private repos as well. Anyway, I chose GitHub for Kite. Here’s the repo: GitHub Kite repo

Set up a continuous integration server

The next step is to set up a continuous integration server. Hudson and Jenkins are both pretty popular open source offerings, but I chose Atlassian’s Bamboo because the UI is a lot more polished. Bamboo is free for open source projects, and even if you decide to buy it, it’s only $10 for the starter license (proceeds go to charity), which gives you a local build agent. Anyway, you can’t go wrong with any of those, so choose one that makes sense and set it up. They’re all easy to set up.

For Bamboo, you’ll need to install Java, Tomcat (or whichever container you like), Git and Maven 3 on the server as well. Bamboo is a Java web app, which is why you need Java and Tomcat. Bamboo uses Git to pull the code down from GitHub, and Maven to build the code. You’ll need to configure this using the Bamboo admin console, once you’ve installed the packages above, you can do the configuration entirely through the Bamboo UI and it’s very easy.

After installing Ubuntu 11.10 server manually, I used Chef to set up everything on my Bamboo server except for deploying the Bamboo WAR itself, since Chef has community cookbooks for Java, Tomcat, Maven and Git. (Note however that currently the URL in the Maven 3 recipe is wrong, so if you go that way then you’ll need to update the URL and the checksum.) Jo Liss has a great tutorial on Chef Solo if you’re interested in giving this a shot. But you don’t have to use Chef. You can just use your native package manager if you prefer to do it that way.

Once you have the executables all set up, you’ll need to create a build plan that slurps source code from GitHub and builds it with a Maven 3 task.

In the screenshot you’ll notice that I created three separate stages here: a commit stage, an acceptance stage and a deploy stage. The idea, following Continuous Delivery, is to separate the fast-but-not-so-comprehensive feedback part from the slow-but-more-comprehensive feedback, and run those as different stages in the build. That way you know right away in most cases where you break the build (commit stage fails), and you still find out soon enough even in those cases where the breakage involves some kind of integration or business acceptance criterion. So in my Bamboo plan I do the commit stage first, then run integration tests during the acceptance stage, and finally deploy the snapshot build to my Maven repo using mvn deploy if the previous two stages pass. That makes it available to others for continuous integration.

Let’s look at the Maven repo part now.

Set up a Maven repo

Sonatype offers a hosted Nexus-based Maven repo for free to open source projects. Moreover they’ll push your artifacts out to Maven central for you as well. So if that sounds good to you, here are instructions on signing up.

JFrog’s Artifactory is an option as well. As you can see from the link, there’s an open source option. We use this at work and it’s pretty nice.

For Sonatype, you’ll need to create a JIRA ticket to get the repo, as per the instructions above. Here’s mine.

Also, your POM will need to conform to certain requirements; see this example for the POM that I’m using for Kite. Nothing too out-of-the-ordinary, though do take note of the parent POM.

Anyway, once you have your Maven repo, practice manually deploying from the command line via mvn deploy just to make sure you’re able to push code. If it works, then you’ll want to try it out from Bamboo. Be sure to update Bamboo’s copy of Maven’s settings.xml so Bamboo can authenticate into the Sonatype repo:

<?xml version="1.0" encoding="utf-8"?>
<settings>
    <servers>
        <server>
            <id>sonatype-nexus-snapshots</id>
            <username>your_username</username>
            <password>your_password</password>
        </server>
        <server>
            <id>sonatype-nexus-staging</id>
            <username>your_username</username>
            <password>your_password</password>
        </server>
    </servers>
</settings>

Once you have it working, you should be able to push your snapshots over to Sonatype. Here’s the Nexus UI, and here’s the raw directory browser view.

Conclusion

Though it takes a bit of effort to set this up, at the end of the day you have a good foundation for your continuous delivery efforts.

In the next post in this series, we’ll expand our deployment pipeline so it can handle pushing a web application to a live, cloud-based container.