In previous entries, I wrote about configuring a project in Hudson and setting up your project to run your MXUnit tests and report results. Before we talk about setting up email and IM communication, let’s briefly look at what you should now have, in pictures, if you’ve set up a project. I’m using MXUnit as the example project here.

First, an entry in the project list, indicating the build’s health

Next, when you drill into the project, you’ll see your recent build results on the left, along with your test trends on the right

On the left side, with your list of previous builds, you can click the “trends” link and see a time trend graph

You can click on a link for your last build and see more details about it. When you click on the Test Results link, you get this view

From there, you can drill down into the reports for more information, should you need it

If a build fails, it’ll show you something like this:

Communicating This Information

All of this information is lovely; however, we’re not interested in monitoring the Hudson interface every time a build runs. Instead, we want to get notified when things change. That’s it: when build status changes. For me, continuous integration is as much about communicating results as it is about providing an easy, scheduled mechanism for running your tests (we don’t care about compiling and linking in CF applications, so that core benefit of CI doesn’t apply to us either).

Ideally, only interested parties would be notified on a change in build status. For example, let’s say a build runs at 8:00 AM, and all tests pass. It runs again at 8:15 AM, and tests fail. What I want to happen is:

1. Hudson looks at source control for the users who have committed code since the last build
2. Hudson notifies *just* those people that the build is now failing.
3. Hudson does this either via email, instant message (SMS), or both.

Fortunately, this is all possible. Let’s set it up.

Configuring Email Settings

From the main Hudson screen, type “configure” in the search box

Scroll down to the bottom and find the E-mail notification section.

I’m using gmail in this case, so I plugged in my gmail credentials, using “smtp.gmail.com” as the server. I’m keeping “default email suffix” blank since this can’t be computed (this would be more for corporate email accounts where you can trust that the email would end up as “firstname” + “lastname” + default email suffix, for example).

In the Advanced settings, I checked “use smtp authentication”, entered my email address into the username field, added my password, checked “use ssl”, and specified the port as 465

Configuring SMS (Jabber) via GTalk

From the “manage Hudson” screen, click on Manage Plugins

go to “Available Plugins”, and find the “Hudson Jabber notifier plugin”. Click things and install it. Restart if necessary.

Now, back in your Manage Hudson screen, you’ll have a new section, right above the Email section, for Jabber.

I entered my gmail address and password, and “talk.google.com” as the server. That’s it!

For the visually inclined, here’s what all of this looks like:

Noise Control

At the project level, you can also configure how noisy you want this communication to be. Here’s what that looks like:

From that image, you’ll see that I can configure when I want to be notified… every build, just on change, etc. Thus, to substantially reduce the noise from your scheduled builds, go into the project and configure it to only notify via IM on status change. This, in my humble opinion, is gold.

Configuring Users

Now that the communication mechanisms are set up, we have to associate email addresses with the subversion users. Quite possibly there’s an easier way to do this via some batch process, but as I’m just getting started with my Hudson investigation, I haven’t looked into it. So please don’t take this as “the only way” or “best practice”, because I do not know that to be true.

For my setup for MXUnit, I linked it to SVN and when it updated and there were changes, it created new a new user for any user that was associated with a change. So, I committed some code to MXUnit, ran a Hudson build, and Hudson added me as a user, silently.

To give the “marc.esher” user notification details:

1. from the main Hudson screen I clicked on “people” then on “marc.esher”. (You can also get here if you know the username you want to configure by typing that username in the "Search” box at the top of the screen)
2. click Configure
3. enter my email address
4. since I installed the Jabber plugin, it also has a space for jabber credentials. I entered my gmail address again.

So what’s all this get me?

After this configuration was finished, here’s what I get:

Emails on build failure that look like this:

GTalk notifications on build failure that look like this:

And corresponding messages for when things go back to normal.

Importantly, what I don’t get: noise. I don’t get notified on every build via email. I don’t have to constantly go to a website to check the build status. I get notifications when I care about them: when things go bad, and when things go from bad back to good.

Summary

Continuous Integration is about communication. It’s about noise control. And so far I’m discovering that Hudson is performing admirably. You can configure different methods of communication, all hooked into source control, with different “strategies” (on every build, on every change, etc). I appreciate this level of configurability. In addition, I was able to get all of this going without reading a single page of documentation. I think that speaks to Hudson’s ease of use.