Easier to do CI than not to.

Run your continuous integration (CI) tests against your Engine Yard AppCloud environments - the exact same configuration you are using in production!

You're developing on OS X or Windows, deploying to Engine Yard AppCloud (Gentoo/Linux), and you're running your CI on your local machine or a spare Ubuntu machine in the corner of the office, or ... you're not running CI at all?

It's a nightmare. It was for me.

But now, Hudson CI, the hudson CLI project, and engineyard-hudson now make CI easier to do than not to for Engine Yard AppCloud users.

And here's some logos:

Installation

gem install engineyard-hudson

This will also install the hudson CLI to interact with your Hudson CI from the command line.

Hosting on Engine Yard AppCloud

Using Engine Yard AppCloud "Quick Start" wizard, create an application with Git Repo git://github.com/engineyard/hudson_server.git (options: rails 3, passenger), and add your own SSH keys. This will create an environment called hudson_server_production. Boot the environment as a Single instance (or Custom cluster with a single instance).

Optionally, though it is quite pretty, deploy/ship the hudson_server application and visit the HTTP link to see the remaining "Almost there..." instructions.

Finally, install Hudson CI and rebuild the environment:

$ ey-hudson install_server

When this completes, visit the URL or refresh the "Almost there..." page to see your Hudson CI server.

Using the hudson list CLI task you can also test there is a working server with no jobs:

For the Hudson slaves' configuration, you'll need:

The hudson_server_production instance public key:

$ ey ssh -e hudson_server_production
# cat /home/deploy/.ssh/id_rsa.pub

Do those steps, copy down the configuration and you're done! Now, you either visit your Hudson CI site or use hudson list to see the status of your projects being tested.

Hosting elsewhere

Hosting Hudson CI on Engine Yard AppCloud is optional; yet delightfully simple. Hudson CI can be hosted anywhere.

If you host your Hudson CI elsewhere then you need the following information about your Hudson CI environment to be able to add EngineYard AppCloud instances as Hudson nodes/slaves:

• Hudson CI public host & port
• Hudson CI's user's public key (probably at /home/deploy/.ssh/id_rsa.pub)
• Hudson CI's user's private key path (probably /home/deploy/.ssh/id_rsa)

Running your CI tests on Engine Yard AppCloud

This is the exciting part - ensuring that your CI tests are being run in the same environment as your production applications. In this case, on Engine Yard AppCloud.

It is assumed that you already have a production application environment (might have multiple applications in it):

In the Engine Yard AppCloud UI, create another environment that matches the production environment exactly (same Ruby, same set of applications, same Unix libraries).

Now, in just a few steps and you will have your applications' tests running in an environment that matches your production environment:

$ cd /my/project
$ ey-hudson install .

Now edit cookbooks/hudson_slave/attributes/default.rb to set up the Hudson CI instance details gathered above.

$ ey recipes upload -e ci_demo_app_ci
$ ey recipes apply -e ci_demo_app_ci

Boot your ci_demo_app_ci environment, visit your Hudson CI and WOW! jobs have been created, they are already running, and they are doing it upon your ci_demo_app_ci environment!

At any time from the command line you can use hudson list to see the status of your jobs

Conventions/Requirements

• Do not use your production environment as your Hudson CI slave. There are no guarantees what will happen. I expect bad things.
• You must name your CI environments with a suffix of _ci or _hudson_slave.
• You should not name any other environments with a suffix of _ci or _hudson_slave; lest they offer themselves to your Hudson CI as slave nodes.
• Keep your production and CI environments exactly the same. Use the same Ruby implementation/version, same database, and include the same RubyGems and Unix packages. Why? This is the entire point of the exercise: to run your CI tests in the same environment as your production application runs.

For example, note the naming convention of the two CI environments below (one ends in _hudson_slave and the other _ci).

What happens?

When you boot your Engine Yard AppCloud CI environments, each resulting EC2 instance executes a special "hudson_slave" recipe (see cookbooks/hudson_slave/recipes/default.rb in your project). This does three things:

• Adds this instance to your Hudson CI server as a slave
• Adds each Rails/Rack application for the AppCloud environment into your Hudson CI as a "job".
• Commences the first build of any newly added job.

If your CI instances have already been booted and you re-apply the recipes over and over (ey recipes apply), nothing good or bad will happen. The instances will stay registered as slaves and the applications will stay registered as Hudson CI jobs.

If a new application is on the instance, then a new job will be created on Hudson CI.

To delete a job from Hudson CI, you should also delete it from your AppCloud CI environment to ensure it isn't re-added the next time you re-apply or re-build or terminate/boot your CI environment. (To delete a job, use the Hudson CI UI or hudson remove APP-NAME from the CLI.)

In essence, to add new Rails/Rack applications into your Hudson CI server you:

• Add them to one of your Engine Yard AppCloud CI environments (the one that matches the production environment where the application will be hosted)
• Rebuild the environment or re-apply the custom recipes (ey recipes apply)

Applications are run in their respective CI environment

Thusly demonstrated below: the application/job "ci_demo_app" is in the middle of a build on its target slave "ci_demo_app_ci". See the AppCloud UI example above to see the relationship between the application/job names and the environment/slave names.

Can I add applications/jobs to Hudson CI other ways?

Yes. There are three simple ways to get Hudson CI to run tests for your application ("create a job to run builds"). Above is the first: all "applications" on the Engine Yard AppCloud CI environment will automatically become Hudson CI jobs. The alternates are:

• Use the hudson create . command from the hudson CLI.

Pass the --assigned_node xyz flag to make the project's test be executed on a specific slave node. "xyz" is the name of another application on your AppCloud account; your tests will be executed on the same instance, with the same version of Ruby etc.

• Use the Hudson CI UI to create a new job. As above, you can make sure the tests are run on a specific Engine Yard AppCloud instance by setting the assigned node label to be the same as another AppCloud application in your account that is being tested.

Specifically, Hudson CI uses "labels" to match jobs to slaves. A common example usage is to label a Windows slave as "windows". A job could then be restricted to only running on slaves with label "windows". We are using this same mechanism.

Automatically triggering job builds

In Hudson CI, a "job" is one of your projects. Each time it runs your tests, it is called a "build".

It is often desirable to have your SCM trigger Hudson CI to run your job build whenever you push new code.

GitHub Service Hooks

• Go to the "Admin" section of your GitHub project
• Click "Service Hooks"
• Click "Post-Receive URLs"
• Enter the URL http://HUDSON-CI-URL/job/APP-NAME/build
• Click "Update Settings"

And here's a picture.

You can also use the "Test Hook" link to test this is wired up correctly.

CLI

Using the hudson CLI:

hudson build path/to/APP-NAME

Curl

You are triggering the build via a GET call to an URL endpoint. So you can also use curl:

curl http://HUDSON-CI-URL/job/APP-NAME/build

Contributions

• Dr Nic Williams (drnic)
• Bodaniel Jeanes (bjeanes) - initial chef recipes for Hudson server + slave

License

Copyright (c) 2010 Dr Nic Williams, Engine Yard

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.