CONTINUOUS
INTEGRATION
Introduction
Continuous Integration is the
topic of quite a bit of buzz in
Silicon Valley and beyond. And
with good reason: continuous
integration helps teams ship
better software at lower cost.
This book will show you how
to get started with Continuous
Integration on your projects
with actionable
recommendations and practical
suggestions.
What is Continuous Integration?
Continuous Integration (or "CI") is a development process where project contributors (developers, designers,
documentation writers, etc.) frequently commit their code to a master repository, which in turn builds and tests the current code after each commit. CI thus can gives an ongoing up-to-date measure of the health of a project's codebase.
Continuous Integration helps teams find bugs and other system problems sooner. This is proven to save money and reduce scheduling risk.
Developers and project managers get an early warning on possible bugs,
incompatibilities, or new performance problems. By identifying these issues soon
after they are introduced, fixing them takes less time and costs less than doing so
at the end of the project.
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Since problems are identified and fixed continuously, there's no
need for a last-minute scramble to fix bugs. This
means reduced schedule risk (and no all-nighters)
Higher initial quality also means lower ongoing
maintenance costs..
Integration to continuous deployment systems ensure rapid turnaround from code update to live
in production. Customer issues get resolved faster, which means increased customer
satisfaction.
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Benefits of Continuous Integration
Since the current version of the codebase is built on
every commit, team members, QA, and sales staff always have a current
build for testing, demo, or release purposes.
Considerations
Infrastructure
Prerequisites
Platforms
Before you begin
Prerequisites
Adding continuous integration to your process
involves getting a few prerequisites in place. It's likely that you already have some or most of these in place on your project. The good news is that all of the
prerequisites provide other benefits to your project, so you can add each one without making a huge push to get CI in place or worrying that it's wasted effort. Here's what you'll want for your CI setup:
Source code repository (like Subversion, Git, or TFS) Automated build (e.g. Ant, Maven, Visual Studio, make, etc.)
Automated test suite
Infrastructure
Once you've got the perquisites in place, you can move forward with adding continuous integration to your process. While you'll get some benefits of continuous integration with only a dedicated build server, adding more realism to your automated testing environment will help you expose a larger percentage of latent bugs before your customers do. In particular, you'll want to run your tests with representative sample data to mimic what your customers will experience.
In rough order of importance, here's what you'll need: Continuous Integration software -- SaaS or on-premises Build & test servers for each of your platforms
Clone of the production environment to run tests Test databases, including test data
Platforms
If your team builds applications that will be used on multiple
platforms, the benefits of continuous integration compound in your favor. That's because a robust CI process makes it easy to build & test each build, on every relevant platform. Once you've gone through the initial effort of setting up a CI process, adding a new server is
comparatively easy. Then, building on testing on all of your platforms is transparent to your contributors. You can even provide a test
matrix to automatically test combinations of platform components. Depending on your customers' use cases, you may want to consider the following for inclusion in your build/test matrix:
Operating system & version Database & version
Language runtime & version Browser type and version
Mobile: Screen sizes & other device capabilities Internationalization settings
Tests
The key benefits of continuous integration derive from its ability to automatically run your test suite every time someone makes a change to the codebase. Your team can write tests with the confidence to know that they will be used every day, to ensure that working code stays working. Over time, as your team identifies new bugs, the test suite will grow to check those conditions. Over time, you may even find that a successful run of the test suite means the code is ready to be released.
The corollary is that if your test suite isn't thorough, continuous integration will give you less actionable
information. However, even if your test suite is limited, a CI system will notify you of build breakages and possible
Yes.
Will Continuous
Integration work with
XP/Agile/Scrum/my
Tools & Resources
The next few pages provide some resources and tools that will help you add continuous integration to your development process. While it's possible to build a continuous integration system from scratch, in practice this will involve writing and maintaining a fair bit of code. This is not likely to lead to efficiency gains, as the staff time involved in building & maintaining the CI system could outweigh the benefits to the team.
Similarly, setting up and maintaining an in-house CI server takes staff time away from core development activities on an ongoing basis. If possible, you may want to use one of the available cloud-based CI systems that offer predictable pricing and require close to zero of your staff's time to setup and administer.
Continuous Integration Software
Continuous integration software is the conductor that drives the logic involved in building & testing your code after every commit. Here are some popular tools, both cloud-based and on-premises.
Suggested Continuous Integration Systems
Apache Continuum
Hudson
Jenkins
BuildLocker by ProjectLocker
TeamCity
Source Code Repository
Your continuous integration software will need to get your latest code from a source control system. If
you're not using a source control system for your code now, you should start immediately, whether or not you plan to add continuous integration. The investment you make in a source control system will pay
consistent dividends over the life of your project.
Suggested source control systems
Git
Subversion
Automated Build Software
Once your CI system retrieves the latest version of your project's code, it will attempt to build the code using your automated build application.
Suggested automated build systems
Ant
Maven
make
Rake
Automated Test Software
Once the build is complete, your automated test suite will be run, with the results collated for your perusal. Testing is a fairly specialized discipline, and there are automated testing tools for many niches. However, there are some good general-purpose open source tools that may be a fit for your projects.
Suggested automated test systems
Appium
Capybara
JUnit
NUnit
Selenium
Bonus: Virtualization
Like all tests, automated tests provide the best quality of information when they are run in a pristine
environment. That way, you know exactly what's being tested (and you know that nobody "fixed" the machine to make the tests work there. Standardizing the test environment helps prevent the "it works on my machine" syndrome by ensuring that tests are 100% reproducible. Virtualization is an excellent way to achieve a reproducible test environment.
