What is Continuous Integration? A Complete Guide to CI

One of the biggest challenges in software development is the integration of the code without actually affecting its stability and functionality. In this, developers mainly face issues like broken dependencies, merge conflicts, etc that slow the speed of the overall software development process. 

To address such challenges, Continuous Integration (CI) is the best solution. It is basically a practice that automates the integration of code change into a communal repository. This benefits the developers and quality testers in identifying and fixing any integration issue easily and early through regular testing and building processes. In this guide, we will discuss continuous integration and CI testing in depth, highlighting its significance, work, challenges, best practices, etc.

What is Continuous Integration? 

Continuous Integration is mainly a DevOps practice in which developers frequently merge their changes into the main branch multiple times a day. As depicted in the figure below, each merge starts an automated sequence of code building and testing that follows the reporting of any issue and again merging to the build and then getting released. Ideally, it is completed in under a few minutes. 

However, suppose the build fails; the CI system blocks its progression to the next stages. In such a situation, the team gives the report on the integration issues to the developers so that they can promptly address the issue, usually within minutes. Hence, we can say that with continuous integration, it is possible to verify each integration of code through an automated build and automated test. It is important to keep in mind that automated testing is not compulsory for CI testing; rather, it is just a practice used here to ensure that code is bug-free. 

Significance of Continuous Integration

Let us now see what are the benefits of Continuous Integration:

• Daily Repository Updates

With CI, developers can daily update the source code repository. 

• Synchronization of Developers

The developers working on projects are coordinated and synced on the changes in the main branch. 

• Early detection of the bugs

It becomes easier for developers to identify the cause of a bug since the change that caused the build to fail can be quickly determined. You can use HyperTest, which is an Integration testing tool that allows early identification of bugs, data errors, any backward incompatible API changes, and critical crashes that happen in the early stage of the development cycle. This, in turn, helps in fixing bugs and preventing them from reaching production. 

• Reduction in Manual Effort

Developers do not need to manually execute the integration process. It lowers the manual efforts as CI automates build, sanity, and other tests.

• Time efficiency

There is no need to spend extensive time updating to the latest version of the main branch.

How Can We Use Continuous Integration?

To implement Continuous Integration, there must be a following of certain procedures and instructions by the team. Let us learn about those steps and take advantage of the CI. 

Continuous Integration Procedure

The following steps you can take for a successful CI process implementation:

• Combine Code: Developers are encouraged to merge their code with the main code repository on a daily basis.

• Code approval: Following the integration process, a validation system needs to be in place to verify that no additional bugs have been introduced. This may include several stages of approval, such as:

• Codescan: This involves checking the code for accuracy and flagging any instances of unused code, improper formatting, or violations of coding standards.

• Automated tests: Here, you execute test cases whenever code is committed to confirm its functionality.

Now, you can repeat the above steps again. 

Establishing a Productive CI Procedure

In order to set up a successful CI process, it is necessary to carry out the subsequent actions:

• Version Control System (VCS): First, you have to implement a VCS to manage and save every check-in as its individual version. Some of the popular options for VSC are Git, Mercurial, and Subversion.

• Version Control Hosting Platform: Now, you have to choose a platform that can host the code and provide VSC functionalities. 

• Single Source Code Repository: The next step is to set up a single repository for the source code.

• Automate Code Building: You have to go further with the CI process by automating the code-building process.

• Automated Tests: Now execute the tests to verify the code’s correctness.

• Daily Commits: You have to make sure that every developer commits to the mainline at least once daily.

• Build Mainline on Integration Machine: Every commit should trigger a build of the mainline on an integration machine.

• Immediate Fixes for Broken Builds: If the build fails, you have to address and fix the issue immediately.

• Fast Build Creation: Make sure the process of creating builds is quick and consistent.

• Testing Environment:  You have to test in an environment that closely resembles the production environment. 

In the above-mentioned process, CI testing is the major step that should not be skipped. This process actually integrates the change to the software project in a central repository and tests them automatically. Let us learn about this in detail from the below section.

CI Testing 

When performing continuous integration, CI testing is the step that helps the team identify and fix any integration error at an early stage of development, thus giving quick feedback to the developer for better improvisation of the software quality. It is the main part of DevOps culture that allows smooth integration of development and operations teams. 

Here's a simplified breakdown of the Continuous Integration Testing process:

• Code Commitment:

  You make a change to the codebase and commit it to the version control system.

• Automated Build:

  This triggers an automated build process, which compiles the code and creates executable files.

  
  

• Automated Testing:

  Automated tests run against the updated codebase to ensure new changes haven't introduced errors or broken existing functionality.

• Test Results:

If Tests Pass:

The changes are successfully integrated, and the process continues with the next set of changes.

If Tests Fail:

You are immediately notified to fix the issue before any further changes can be made.

By following these steps, CI testing helps maintain a stable and error-free production environment.  

Now that we have discussed methods to perform continuous integration and CI testing, let us now see which tools can be used to execute the method. 

Continuous Integration Tools

Some of the popular continuous integration tools available for your use are as follows: 

Jenkins 

It is one of the most popular CI tools that allows automatic building, integrating, and testing of code immediately after it's committed to the source repository. It helps you identify errors sooner and release software more quickly. 

Buildbot

Buildbot is capable of automating every part of the software development process. In the role of a job scheduling system it lines up and carries out tasks while providing feedback, making your development process more efficient. 

Go

Go is distinguished by its pipeline concept, which simplifies the process of designing intricate build workflows. This functionality makes it easier to handle and display your CI workflows.

Travis CI

Travis CI is considered one of the most established and reliable hosted options, offered as both a hosted service and on-premises version for enterprise deployment. It is a dependable choice for your CI requirements. 

GitLab CI

GitLab CI is a free hosted service that plays a crucial role in the open-source Rails project. It provides comprehensive Git repository management with functions such as access control, issue tracking, code reviews, and others, delivering a complete solution for your CI needs.

Continuous Integration Use Case

Imagine you have two software developers needing to improve their DevOps process. They must regularly integrate and test their code, but scheduling these tasks manually takes too much time. They have to come to a mutual agreement on the timing of starting a test, the way to communicate the result, and the process of confirming successful integration.

It is important to note here that CI testing tools come with pre-set configurations for the above-mentioned tasks and also offer the option of personalization. 

An automatic CI system, like Jenkins, solves this by running integration tests whenever new code is checked in. The result will show that the code is integrated smoothly, with logs and metrics to track success rates. 

If developers use compiled languages, it will result in a default test if code compilation is successful. If they are not using the compiled language, new code will break the build. Custom tests are needed for languages like Python or JavaScript to address this. 

Best Practices of Continuous Integration

Treat your master build as if it's always ready for release. Here are some essential guidelines to follow:

• Maintain Test Integrity: Don't comment on failing tests. Instead, file an issue and address it promptly.

• Keep Builds Stable: Never check in code on a broken build, and don't leave for the day if the build is broken.

• Optimize Build Speed: Aim for build times of up to 10 minutes to ensure a fast feedback loop. Longer builds can slow down the development process.

• Test in Production-like Environments:

  Use a clone of the production environment for testing. You can define your CI environment with a Docker image to match production closely, reducing bugs due to environmental differences.

Conclusion

From this article, you should have understood the concept of continuous integration and the optimal techniques and tools for CI testing that could benefit you in upcoming projects. You can further leverage continuous integration by automating the process and executing CI testing to validate code change. 

Based on the information in this article, it is suggested that top companies prioritize strong CI pipelines and readily invest in improving efficiency further. This is crucial in today's agile and fast-paced development environments, as it improves efficiency, reliability, and overall software delivery.