What Is Continuous Integration?

Key Takeaways

Continuous integration (CI) is part of software development best practices and helps development teams organize work into manageable automated testing and deployment iterations within a shared repository.

• Continuous integration is a commonly used methodology within software development. 

• This practice allows development teams working on different projects to merge code changes from multiple sources into a central repository, automating testing and deployment.

• Continuous integration is important for delivering higher-quality code faster and can be used with other methodologies, such as Agile.

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What is continuous integration?

Continuous integration occurs when team members merge code into a central repository, which is then automatically built and tested multiple times a day. CI includes a feedback loop that automates code changes. This practice allows code changes and new features from multiple sources to integrate seamlessly into the main code. 

Development teams working on different project features can work independently using branches created off the main repository of code. CI sytems allow them to isolate a workspace and test new ideas without harming the working code. Once new features are ready for integration into the main repository, they are merged into the main code via pull requests.

At this step, the tools that provide automation, testing, and version control are essential to creating continuous integration practices. When a CI server or other CI tool detects new changes, it compiles them, provides testing, packages them, and deploys the new code into the main working code. This supports developer work, eliminates time consuming tasks, and allows teams to automate building and testing.

How continuous integration works

Continuous integration is a DevOps best practice because of its benefits to teams using it. Here are some reasons continuous integration is valuable: 

• Faster iterations: Continuous integration acts as a safety net during software development. This process begins with code committing, where developers break their work into manageable pieces which are saved to a central repository several times each day. This ensures that team members can combine their work frequently, avoiding large-scale infrequent merges. Automating parts of the process, such as testing, allows developers to spend more time coding.

• Higher quality code with fewer bugs: Smaller code changes make spotting and fixing bugs and other problems easier. You can also find bugs earlier in the process and use automation to perform more kinds of testing than you would otherwise. After the build, the server runs tests on individual functions and integrations, eliminating the need for manual checks. This immediate feedback shares whether the changes worked. This can prevent small bugs from snowballing into complex problems later in the development cycle.

• Ability to roll back changes: If something goes wrong and a new update somehow breaks your code, continuous integration allows you to roll back the latest changes and immediately revert to a time when the code was working. This is a crucial feature for software updates, so you don’t disrupt people using your software. 

• Reduced expenses: Reduced errors and bugs and increased automation allow development teams to spend more time developing new code and features in a production environment, reducing the cost of creating new features and software. 

What is continuous integration used for?

Development teams use continuous integration to provide automated solutions for building, testing, and deploying code and updates to code. Your team can use continuous integration in conjunction with other tools, such as Agile and continuous delivery.

1. Agile integration

You can use continuous integration with Agile, a project management methodology that separates tasks into items on a project roadmap. Doing so allows you to organize your team and distribute tasks efficiently.

2. Automated continuous integration testing

Continuous integration allows solutions for automated testing, including:

• Unit tests

• Integration tests

• Acceptance tests

3. GUI testing

In graphical user interface (GUI) testing, CI helps streamline and organize testing efforts to free up developers from this tedious task.

4. Used with continuous delivery

Continuous integration is often associated with continuous delivery, sometimes called CI/CD. These terms are sometimes interchangeable but refer to parts of the same process. Continuous integration focuses on building, testing, and compiling the new features into a central repository. In contrast, continuous delivery refers to pushing those updates out into working code and consistently delivering more minor updates.

CI tools 

The tools you choose to help you implement CI are among the critical parts of continuous integration. Some popular choices include:

• Jenkins

• TeamCity

• GitLab

• Bamboo

• CircleCI

• TravisCI

• BitBucket Pipelines

• Buildbot

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