What is Continuous Integration (CI)? Here is Everything You Need to Know

What is Continuous Integration (CI)? Here is Everything You Need to Know
With the software known as Cruise Control, Continuous Integration was first introduced in the year 2000. And, it has become a key practice in any software organization over the years.

Yes, this is a development practice that calls upon development teams to ensure that for every code change made to a software program, a build and subsequent testing is conducted. This idea was meant to eliminate the problem of finding late occurrences of issues in the build lifecycle.

So, in all, it could be said that the Continuous Integration was introduced to ensure that the code changes and builds were never done in isolation, instead of the developers working in isolation and not integrating enough.

But this is not enough to understand what is Continuous Integration, so let’s begin with its introduction. But before that, we will also learn about traditional integration to understand it well.

What is Meant by Traditional Integration?

In Traditional Integration of the software development life cycle,

1. Every developer receives a copy of the code from the central repository.
2. All developers begin at the same starting point and act on it.
3. All developers make progress by working on their own or in a team.
4. They add or change classes, functions, and methods shaping the code to meet their needs, and ultimately, they complete the task they were assigned to do.
5. Meanwhile, the other developers and teams continue working on their tasks, solving the problems they have been assigned, changing the code, or adding new code.
6. If we take a step back and look back at the entire project, i.e., the big picture, we can see that all developers working on a project are changing the context for the other developers as they are working on the source code.

Well, the major factors that can make these problems escalate are:

1. It’s the size of the team running the project.
2. Since the developer got the latest version of the code from the central repository, the amount of time passed. 

What is Continuous Integration?

The method of automating the integration of code changes from multiple contributors into a single software project is what we call Continuous integration (CI). The process of CI is comprised of automatic tools that assert the new code’s correctness before integration.

Moreover, a source code version control system is the crux of the CI process. The version control system is also supplemented with other checks like syntax style review tools, automated code quality tests, and more.

The renowned software developer, author, and international public speaker Martin Fowler’s definition goes as:

“Continuous Integration is a software development practice where members of a team integrate their work frequently, usually each person integrates at least daily - leading to multiple integrations per day. Each integration is verified by an automated build (including test) to detect integration errors as quickly as possible. Many teams find that this approach leads to significantly reduced integration problems and allows a team to develop cohesive software more rapidly.”

In all, automating our build, test, and deploy processes can increase the problems commonly occurring on projects. Hence we need to use a reliable method of integrating that will ensure that the errors can be detected sooner than later.

Importance of CI

It would be helpful to discuss some pain points first, which often arise due to the absence of CI for understanding the importance of CI. At first, developers used to manually communicate and coordinate when contributing code to the end product without CI.

And, this coordination extends beyond the development teams to the rest of the organization as well. Also, the members of the product team must coordinate with the other team members, especially those who will be responsible for sequentially launch features and fixes.

Well, it could be said that the communication overhead of a non-CI environment can become complex and complicate the synchronization chores, which ends up adding unnecessary bureaucratic costs to projects.

And, it further results in slower code releases with higher rates of failure as it demands that developers must be thoughtful and sensitive towards the integrations. Most importantly, the way engineering team and codebase sizes increase, these risks also grow exponentially.

Moreover, a disconnect between the engineering team and the rest of the org can occur without a robust CI pipeline. Also, communication between engineering and product can be cumbersome.

What CI Does?

In simple words, CI serves to scale up headcount and delivery output of engineering teams. And, software developers can work independently on features in parallel if we have introduced CI to the mentioned scenario.

In all, we can say that in modern, high-performance software engineering organizations, CI is one valuable and well-established practice.

How Can CI be Used?

Well, alongside an agile software development workflow, CI is generally used. An organization will compile a list of tasks that comprise a product roadmap. These tasks are then distributed amongst software engineering team members for the delivery.

Moreover, the inclusion of CI allows such software development tasks to be developed independently and in parallel amid the assigned developers. Once one of these tasks is complete, a developer will introduce new work to the CI system to be integrated with the rest of the project.

Requirements for Installing the CI System

One might be thinking of what could be the requirements for the installation of the CI system. But yes, we’ll surely need a few things first if you want to install the CI server in your environment.

1. Version Control System (VCS)

To centralize and preserve changes made to your project over time, VCS provides a reliable method.

2. Virtual Machine

It is necessary to have a spare server or at least a virtual machine for onsite solutions.

3. Hosted CI Tool Solutions

One can go for hosted CI tool solutions that help in the maintenance of the whole process and offers easier scalability to avoid servers as well as virtual machines.

4. Tools

We will need to install one of the many available continuous integration tools like Jenkins, Bamboo, TeamCity, etc. especially if we opt-in for the self-hosted variant.

Benefits of Continuous Integration

To any software producing organization, CI is one valuable asset. Usage of CI not only benefits the engineering team but the overall organization also. It allows better transparency and insight into the process of software development along with the delivery.

So, all such benefits allow the rest of the organization to better plan and execute go-to-market strategies. Here are some of the overall organizational benefits of CI.

1. Reduced Integration Risk

Usually, working on projects implies many people are working on the same project but with separate tasks or parts of the code, which makes it unsafe to integrate.

However, solving and debugging the issue can be painful and can potentially mean a lot of changes to the code. So, frequently integrating all can help reduce these kinds of problems to a minimum.

2. Higher Code Quality

As it helps in focusing more on the functionality of the code, therefore, it ends with the higher quality product.

3. The Code in Version Control Works

You and your team get the notice immediately if you commit something that breaks the build, plus the problem is also fixed even before anyone else pulls the “broken” code.

4. Reduced Friction between Team Members

It reduces the frequency of quarrels among team members by having the impartial system in place.

5. Easy for QA Team

Isolating and tracing bugs can be efficient by having different versions and builds of the code, and it makes life easier for the QA team.

6. Less Time in Deployment

Deploying projects can be very time-consuming and tedious, and automating that process makes perfect sense.

7. Technology Learning Curve

A list of supportive technologies comes with CI functionality that may be learning curve investments for the team to undertake. These technologies are hosting infrastructure, version control systems, and orchestration technologies.

Jenkins – The Ultimate CI Tool

Along with the plugins built for Continuous Integration purpose, Jenkins, written in Java, is an open-source automation tool. Making it easier for users to obtain a fresh build and for developers to integrate changes to the project, it is used to test as well as build our software projects continuously.

It further enables us to continuously deliver our software by integrating with a large number of testing as well as deployment technologies.

Organizations can accelerate the software development process through automation with the help of Jenkins. Including build, test, document, package, deploy, stage, static analysis, and much more, it integrates development life-cycle processes of all kinds.

Well, it could be said that the Jenkins achieves Continuous Integration by the help of plugins. Yes, the plugins enable the integration of several DevOps stages. So, all we need is to install the plugins for that tool if we want to integrate a particular tool. For instance: Git, Amazon EC2, Maven 2 project, HTML publisher, etc.

Continuous Integration vs. Continuous Delivery vs. Continuous Deployment

1. Continuous Integration

As we learned earlier also, it is the practice of integrating changes from different developers in the team into a mainline as early as possible, in the best cases, several times a day.

Apart from that, it makes sure that the code on which individual developers work doesn’t divert too much. Plus, continuous integration can enable our code to be dependable when we combine the process with automated testing.

2. Continuous Delivery

And, the practice of keeping our codebase deployable at any point is what we call Continuous Delivery. It has to have all the configuration necessary to push it into production, beyond making sure our application passes automated tests.

And, to ensure a fast development loop, various teams then do push changes that pass the automated tests into a test or production environment immediately.

3. Continuous Deployment

Continuous Integration and Continuous Deployment are somehow closely related. Plus, if the latest version passes all automated tests, it refers to keep our application deployable at any point or even automatically releasing to a test or production environment.

Some Best Practices of CI


1. Test-Driven Development

It is one best practice to constantly develop and improve the test coverage once a project has established a CI pipeline with automatic test coverage. However, to assert that the new code is behaving as expected, each new feature coming down the CI pipeline should have an accompanying set of tests.

Plus, before doing any actual feature coding Test-Driven Development (TDD) is the practice of writing out the test code as well as the test cases. The product team can help craft an expected business behavior specification, which can then be transformed into the test cases in pure Test-Driven Development (TDD).

Moreover, developers and product team will meet and discuss a spec or list of requirements in a pure TDD scenario. Such a list of requirements will soon be converted into a checklist of code assertions. And, the developers will then write code that matches such assertions.

2. Optimize Pipeline Speed

As we know that the CI pipeline is going to be a central as well as frequently used process, it is essential to optimize its execution speed.

The rate of feature releases, team size, and codebase size grow as soon as the CI workflow compound exponentially. So, this is one best practice to measure the CI pipeline speed and optimize as required.

The faster the product feedback loop enabled, the faster the CI pipeline is. Plus, to help improve the user experience, developers can rapidly push changes and experiment with new feature ideas.

Moreover, any error or bug fixes can be quickly patched or resolved as discovered. This increased execution speed will not only benefit us to get over other competitors and but will also offer an overall higher-quality experience to our customers.

3. Pull Requests and Code Review

Many of the modern software development teams practice a pull request and code review workflow. No wonder that for effective CI, Pull requests are a critical practice. And, when a developer is ready to merge new code into the main codebase, a pull request is created. It further notifies other developers of the new set of changes that are ready for integration.

If one needs to kick off the CI pipeline and run the set of automated approval steps, Pull requests are an opportune time. An additional, manual approval step is commonly added at pull request time during which a non-stakeholder engineer performs a code review of the feature.

And, to review the new code and functionality, it allows for a fresh set of eyes. The non-stakeholder will edit suggestions and approve or deny the pull request.

Moreover, to foster passive communication and knowledge share among an engineering team, Pull requests and code review are powerful tools. This helps guard against technical debt in the form of knowledge silos, where specific engineers are the only stakeholders for certain features of a codebase.

Final Words

So, this is an opportunity to truly enhance our team’s quality of life, especially if our organization has a multiple-developer software team and is not using CI. Yes, we have already seen how it will help our engineering org execute quicker and more effectively. Besides, most of the software developers expect an organization to have CI established, so  CI is certainly worth the investment when it comes to acquiring and retaining best-in-class developers.

There is no doubt that especially for modern high-efficiency software development organizations, CI is one standard fixture. The best companies have robust CI pipelines and don’t think twice about further efficiency investments. The benefits of CI apply to the whole organization.

Besides, many third-party tools are there to help in CI management and installation. One indeed has many options to choose from; some popular options are Codeship, Pipelines, Bitbucket SemaphoreCI, Jenkins, CircleCI, Bamboo, Teamcity, and many others. And, all such tools have their in-depth setup guides and documentation to help get started.

So, what keeps you waiting? Start using CI in your organization and lead multiple integrations every day!
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