The Complete Expert Guide to Continuous Integration

by Alastair Wilkes in

What is Continuous Integration, it’s role in DevOps culture, and how to get started with CI/CD

Business demands on software development continue to increase overtime, with the need for faster turnarounds driven by consumer demand. Development teams have looked to find ways to reliably release a consistent flow of software updates in order to speed up release cycles. Faster release cycles result in lower costs and reduce the risks associated with development. Out of these demands emerged the CI/CD pipeline, helping deliver quality code faster.

The CI/CD pipeline is an automated approach for teams to quickly and continuously speed up their software development lifecycles with three phases: Continuous Integration, Continuous Delivery, and Continuous Deployment. Development teams practicing effective CI/CD frameworks are able to effectively increase their software development and release practice velocity.

As your ultimate guide to Continuous Integration, this article answers all your questions about Continuous Integration, including:

What is Continuous Integration?

Continuous Integration is a DevOps software development practice where developers regularly merge their code changes into a central repository, after which automated builds and tests run. Automating the integration of code changes from multiple developers into a single software project streamlines merging new code and reduces the workload on developers.

Without Continuous Integration developers experience “merge or integration hell'', where the time it takes to integrate to the main branch is longer than the time it takes to actually make the changes. In this scenario, when starting a new piece of code, a developer takes a copy of the current code base to work on. As other code changes are submitted by other developers into the source code repository, the code base copy the first developer has will stop reflecting the repository code.

New code, resources, and libraries create dependencies and cause conflicts for merging. Over time, the more development continues on the branch without merging, the more risk of integration failures increases. The more changes the code repository has, the  more work developers have to do in order to submit their code changes. 

Continuous Integration ensures applications function properly, whenever new code changes are integrated into the main branch. Continuous Integration includes the build or integration stage of the software release process. 

How does Continuous Integration work?

In the Continuous Integration workflow, developers check in the code to the main repository, and the code builds. Automated tests run on the build and a results report is sent. If the tests pass, the executable is created and shared for development to do another check-in. If a test fails the developer that submitted the change works on the fix and checks it into the system again through the same process. Within this cycle, Continuous Integration also includes continuous monitoring of the main repository.

Continuous integration workflow

Continuous Integration automatically builds and runs tests on the new code changes to immediately highlight any errors, bugs, or flaws. In order to do this, the practice of Continuous Integration requires developers to consistently and frequently integrate their code into a shared repository, up to multiple times a day. Each and every integration is verified by an automated build and automated tests. 

How does Continuous Integration fit into CI/CD?

Continuous Integration is the first phase of the CI/CD pipeline. Combined with Continuous Delivery to me the CI/CD pipeline, this framework empowers development teams to automate their software releases. 

As the first phase, Continuous Integration (CI) includes automating how developers build, test, and merge code changes into the shared repository.

How does Continuous Integration fit into CI/CD?


In the second phase, Continuous Delivery (CD), developers focus on enabling code to be released for production. It’s important to note that CD can also refer to Continuous Deployment, a practice that automates the final deployment directly to production, rather than relying on the manual production trigger within Continuous Delivery practices.

Related Article: Continuous Delivery VS Continuous Deployment

CI/CD allows developers to more quickly and efficiently deliver software changes to their customers through the use of ongoing, smart automation and continuous monitoring throughout the development lifecycle.  

Together, Continuous Integration and Continuous Delivery support DevOps methodology, helping to boost efficiency, speed, and collaboration to optimal levels during the entire software development lifecycle. 

What’s the difference between Continuous Integration, Continuous Delivery, and Continuous Deployment?

While Continuous Integration may often be viewed as a part of Continuous Delivery and Deployment, these phases are actually quite different.

Continuous Integration involves the building and testing stages of the software release process. The goals of Continuous Integration are to enable multiple developers to work on the same application individually, to speed up releases, and to detect errors more quickly and easily in the initial stages of the software release cycle.

On the other hand, the goal of Continuous Delivery is to be able to reliably release application changes at any given moment. Continuous Delivery includes all stages of the software development process, from idea to production, and follows Continuous Integration.

Meanwhile, the goal of Continuous Deployment is to always keep code in a deployable state. This is achieved by the frequent, automated deployment of the repository to a production environment after automated testing. Continuous Deployment is also an extension of Continuous Integration.

While the goals of Continuous Integration, Continuous Delivery, and Continuous Deployment are all different, Continuous Delivery and Deployment can also be seen as expansions of Continuous Integration. 

Continuous Delivery builds on Continuous Integration by automatically deploying all code changes to a testing or production environment after building. Continuous Deployment builds on Continuous Delivery, and thus Continuous Integration as well. 

Together, an efficient CI/CD pipeline empowers DevOps teams to avoid code defects with smaller code changes and fault isolations, increase test reliability, and speed up the velocity of their releases.

The primary goals of DevOps are twofold. First, DevOps seeks to optimize the workflow of software development and operations teams. Second, DevOps aims to deliver the highest value software applications and services to the customer, as quickly as possible, without ever sacrificing quality. 

DevOps is a framework that helps organizations to rapidly improve and deliver software, create the best customer experience, and retain a competitive edge. To this extent, Continuous Integration is a key component to successful DevOps teams. 

The main intention of Continuous Integration is to merge changes into the main branch automatically, to minimize the integration challenges that may arise when multiple developers work on the same project. Continuous Integration achieves this aim by incorporating automation of the first stages of the CI/CD pipeline, or the initial building and testing phases. 

Additionally, Continuous Integration streamlines workflows and improves the communication and efficiency of DevOps teams. By minimizing communication issues and sidestepping the tangled red tape of manual code integration, Continuous Integration enables every team member to create and manage a code update all the way to release. With Continuous Integration, individuals can work alone, but know their code will smoothly integrate into the repository, without issue.

It’s also important to note that Continuous Integration does not only benefit developers and the operations teams. Continuous Integration improves an entire organization with bolstered communication and transparency of the entire software development and delivery to the customer.

For speedier, more efficient workflow and software improvements, Continuous Integration is crucial to achieving these two core DevOps principles. Fail fast, learn fast, deliver with confidence - that’s what DevOps and Continuous Integration is all about.

Continuous Integration Benefits

Continuous Integration offers three major benefits to DevOps teams: faster bug remediation, boosted developer productivity, and increased release velocity.

1. Find and address bugs quicker

To begin, Continuous Integration helps developers to uncover bugs more quickly. With Continuous Integration, developers must frequently commit to a shared repository and can run local unit tests on code to determine the accuracy and efficacy before an integration. A smart Continuous Integration service will automatically build and run unit tests on these new code changes and immediately uncover any flaws or errors. 

With this kind of frequent testing, it’s easier for DevOps teams to discover and address bugs early on, before they accumulate or cause bigger issues down the road.

2. Improve developer productivity

Additionally, Continuous Integration works to improve developer productivity - and happiness. With code changes continually merged, Continuous Integration saves manual effort, time, and creates a faster workflow. For customers, Continuous Integration also means faster releases and higher levels of satisfaction with DevOps teams. 

3. Speed up the release of new software updates or applications

Lastly, Continuous Integration is beneficial because it helps to speed up software release times.

Continuous Integration automates the integration of code changes from various contributors into a single software release or app.  

Without practicing Continuous Integration, developers work on code changes solo, then merge into the repository. That kind of solo work effort creates silos and makes the task of code changes slower and more tedious. Continuous Integration slashes silos and speeds workflow. Effective Continuous Integration empowers teams to adopt successful Continuous Delivery and Deployment practices.

Continuous Integration Best Practices

Before you starting adopting Continuous Integration into your software development lifecycle, here are some critical best practices to adhere to for success:

  • Always keep the build green: If the main branch for the build breaks, it must become top priority. There is no point in adding more changes into a broken build. It will only make it harder to fix what is broken.
  • Integrate early, integrate often: The key to successful Continuous Integration is integrating as early and as often as possible, avoiding risks by reducing merge conflicts. Merging code earlier lessens the amount of changes so solutions are far easier on developers when conflicts occur. Changes are smaller making it easier on your developer collaboration.
  • Write automated tests for every feature developed: Save yourself the pain of regressions and bugs and write tests as part of your stories for every feature developed. Also be sure to write tests when you solve a bug to prevent them in the future.

How to Get Started with Continuous Integration

To get started with Continuous Integration you’ll want to ensure your team is aligned on DevOps methodology. Here are some steps to get you started in the right direction:

  • Maintain a code repository & version control: A code repository should be in place as well as a version control system to ensure that every check-in is stored as a separate version.
  • Automate the build and testing: Automate the build, as well as running tests on every branch of your repository and every push to the main repository. Start small with unit tests, the move to integration tests, acceptance tests, and UI tests. Remember, not all tests are equal.
  • Get a Continuous Integration service to run your tests automatically: In order to automate your testing, you’ll need a service to monitor your main repository for new changes. There are on-site and Cloud options depending on where your code is hosted, how much resources you need for your test, and the amount of developers merging code.
  • Keep build time under 3 minutes: Optimizing your build time enables your team to focus and move code safely and efficiently. Leverage caching to optimize your build time when there’s no change in dependencies. 

Continuous Integration Tools

Efficient Continuous Integration tools offer source control version management, test automation, automatic build, and automatic deployment. Here are the top Continuous Integration tools:

  • Bamboo: A CI server that automates software application release management, Bambook handles building and functional testing, versioning, release tags, all the way to deployment.
  • Circle CI: As a cloud-based CI tool, Circle CI supports rapid development and publishing. It Integrates with Bitbucket, GitHub and GitHub Enterprise, and allows you to run builds using a container or virtual machine
  • CloudBees Codeship: Cloud-based CI tool for GitHub, Codeship integrates with any tools, services and cloud environments.
  • GitLab: With the main product as a web-based Git repository manager for issue tracking and analytics, GitLab lets you trigger builds, run tests, and deploy code with every commit or push.
  • Jenkins: Originally developed by Kohsuke, Jenkins is an open-source, platform-independent Java-based CI tool. With hundreds of plugins available, Jenkins supports building, deploying, and automating for software development projects and can be configured via a console or a graphical user interface. 
  • TeamCity: Developed by JetBrains, TeamCity is a cloud-based build management and CI server. It runs in a Java environment and integrates with Visual Studio and IDEs, and also supports BitBucket and GitLab server pull requests.
  • Travis CI: One of the first CI solutions, the tool is free for open source projects to build and test projects. It automatically detects new commits and pushes to GitHub repository. After every code commit, Travis CI will build and run tests.


With effective Continuous Integration, organizations can detect errors earlier, saving time and effort by speeding up the quality feedback loop. Bug counts are drastically reduced earlier in your cycles and manual testing efforts are reduced with the automated testing. 

Launchable is ready to improve your CI/CD pipeline withPredictive Test Selection, identifying the most critical tests for each code change to run. With Launchable, DevOps teams can increase the velocity of their software releases and improve workflow, productivity, and morale.

Ready to see how Launchable ML can improve your CI/CD pipeline? Contact Launchable for a POC and schedule your free demo today.

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