Continuous integration and continuous delivery explained

Continuous integration (CI) and continuous delivery/deployment (CD) are part of Agile methodologies in the software development lifecycle (SDLC). Together CI and CD are responsible for the optimal functioning of most SaaS (software as a service) products, as well as businesses that are powered by websites and software applications.

Continuous integration - CI deals with regularly integrating new code changes to existing code during development. These builds are tested continuously so that there are fewer errors when new changes are merged into the main codebase for release. CI helps developers the most by automating building, testing, and packaging builds, thereby giving them time to work on fixes and new product features.

Continuous delivery/deployment - CD is an extension of CI; it's the process of automating the tests of builds and pushing them into the production environment once the required tests are passed. The final step of launching the software can be either automated or done manually. Depending on the choice, it's referred to as continuous delivery when manual and continuous deployment when automated.

The era before CI/CD

Even though CI/CD is a core aspect of DevOps, it predates the latter by decades, at least in its primitive form. Back then, an update to any major software was released only once every year or two, due to the difficulty of repetitive manual testing. It meant that the update was not just a minor increment but rather a consolidation of various bug fixes and new feature additions, which also increased storage size.

Since the internet was sluggish and barely usable compared to today's standards, it was difficult to acquire software updates in the first place—and due to inefficient testing, updates often introduced many new bugs, even though it solved old ones. The absence of dedicated support and a lack of widespread software expertise among users also made it difficult to apply patches for the new bugs that arose.

Role of CI/CD in SDLC

CI/CD paired with software development and testing tools has become an integral part of the SDLC, acting as a bridge between development and testing teams, to get the software ready for the production phase. CI deals with the simultaneous and repeated testing of different software builds without disturbing the production phase of the application. When the build is ready, it's pushed to the main branch of the codebase as part of CD. Since the build is already tested, no further testing is required.

Continuous testing plays a key role in the CI/CD pipeline by ensuring that different stages are handled effectively without the need for intervention from the QA team. Once the build is pushed for testing, test automation can be triggered and final testing can even be automated to verify stability of the application before the production phase.

Benefits of CI/CD

CI/CD has many benefits in the SDLC. A few of the important ones are:

• Incremental changes - CI/CD enables teams to make incremental code changes, which contribute to frequent updates for the software. 

• Faster delivery - The processes enabling CI/CD also make simultaneous continuous testing possible, which greatly reduces the time required to test the software build.

• Flexibility - The CI/CD pipeline offers granular control over different build versions of the software, giving the QA team the flexibility to work with various builds. This ensures that reverting back to previous builds in case of an issue is much easier and faster.

• Improved efficiency - CI/CD involves the simultaneous development and testing of different software builds. Each build is modified and thoroughly tested before they're pushed to production.

• Better collaboration - Continuous testing and frequent changes to the software requires deeper collaboration between teams.

• Customer satisfaction - Customer experience holds more weight than it did decades back, and the product team is constantly getting feedback from users. CI/CD aids in quickly tweaking and delivering software to achieve a good user experience.

Challenges in the CI/CD pipeline

CI/CD pipelines have a positive impact on the SDLC of an application, but they also come with a unique set of challenges:

• Security - CI/CD pipelines have certain vulnerabilities compared to the actual software in the production environment. This makes it easier for hackers to try and access sensitive information, and in some cases even change the code for a backdoor attack when the build goes live.

• Multiple builds - Teams simultaneously work on multiple builds of the software, and most of them are tested on shared environments, which greatly affect the efficacy of testing. Tracking the individual builds and managing them is resource intensive and requires coordination between teams.

• Communication - Not all builds make it to production—without proper communication, each one of them will go through development and testing, which wastes resources. Communication also ensures that production-ready builds require minimal or no testing in the future.

Tips for achieving better results using CI/CD

Challenges affecting the CI/CD pipelines can be alleviated by:

• Regular commits - Commits to the code repository have to be regularly done, to ensure that there are fewer changes as a whole between each commit. 

• Manageable chunks - As the project grows, so does the number of functionalities that need to be tested. Each functionality is dependent on various other functionalities, so it's easier and more efficient to test them in parts, especially in a large-scale application.

• Planning - Between developing and testing multiple software builds, followed by taking them live, an overview of the entire process, coupled with constant monitoring, is achievable with proper planning.

• Collaboration - Collaborating between teams is the most important aspect of an Agile project. Communication is pivotal, as it ensures that both the development and QA teams can collaborate efficiently on different builds of the software.

• Version control - Managing different versions of software can be a tedious task, but with an efficient CI/CD tool and proper planning, granular control can be achieved over individual versions.

CI/CD tools and test automation

Test automation is the best way to get the most out of CI/CD, which requires continuous testing, integration, and deployment. But just having a CI/CD tool only solves part of the problem. Once development is done, efficient and versatile test automation software like Zoho QEngine can integrate with the CI/CD tool to orchestrate various steps of the software testing lifecycle.

Zoho QEngine is test automation software that can assist with writing test cases via no-code, low-code, or pro-code for web, mobile, and API platforms. Its parallel testing and self-healing features expedite the testing process. Analyzing the results and collaborating with relevant teams is effortless on Zoho QEngine.