Introduction

In the domain of software development, practices like continuous integration (CI) and continuous delivery (CD) have become essential. Both CI and CD are usually integral components of agile development, a methodology characterised by iterative development cycles, collaboration and adaptability to changing requirements. Together, these practices help development teams to have greater responsiveness to customer needs. In this article, we enter into the principles and benefits of CI/CD within the context of agile development, exploring how they accelerate the delivery of value to stakeholders.

Formula 1 pit crew preparing for a race

Continuous integration (CI) is like a Formula 1 pit crew working together during a race. Each member has a specific task, such as changing tires, refuelling and adjusting the car’s settings. Instead of each crew member working independently and waiting until the end of the race to make adjustments, they work together simultaneously. So, while one crew member is changing tires, another is refuelling and another is tweaking the car’s aerodynamics. This way, they integrate their tasks as soon as they are ready. Similarly, in software development, CI ensures that whenever a developer makes changes to the code, it is immediately integrated with the rest of the codebase and tested, ensuring smooth performance.

Illustration: Formula 1 pit crew

Continuous delivery (CD) in the Formula 1 context is like ensuring the car is always race-ready. Every time the car comes into the pit stop, it undergoes the same process of tire changes, refuelling and adjustments and once it is done, it is immediately ready to go back on the track. In software development, CD ensures that whenever new code is integrated, it goes through a process of testing and packaging so that it is always ready to be deployed to users. This means that at any point, there is a potentially deployable product ready for release.

In summary, CI ensures that code changes are integrated smoothly and CD ensures that the software is always ready to be shipped.

Or else?

Imagine another Formula 1 pit crew preparing for the same race, using the opposite approach.

It would be like if each member of the pit crew worked independently on different tasks, such as changing tires, refuelling and adjusting the car, without communicating or coordinating with each other. This lack of collaboration could lead to chaos during the pit stop, with crew members getting in each other’s way and making mistakes.

Similarly, it would be like if the pit crew only serviced the car occasionally and each time they did, it was a slow and manual process. This could mean the car spends more time in the pit lane, losing valuable time during the race and the quality of the pit stop could vary widely depending on how often they practise.

In essence, the opposite of CI/CD in a Formula 1 pit stop would involve a disorganised and infrequent approach to servicing the car, leading to inefficiencies, errors and delays in getting the car back on the track.

More about CI/CD

Let us bring more light on continuous integration and continuous delivery.

Continuous integration is like a sophisticated version control system. Imagine you are working on a project with multiple developers. Instead of each developer working on their own version of the code and merging it all together at the end, CI means that every time someone makes a change to the code, it is immediately integrated with the main codebase. This ensures that any conflicts or errors are caught early and can be fixed before they cause bigger issues. Essentially, it is about keeping the codebase in a constantly usable state by integrating changes frequently.

Continuous delivery is like having a well-oiled deployment pipeline. It is all about ensuring that your software is always in a state where it can be released to users at any time. This involves automating the process of building, testing and deploying software so that new features or updates can be delivered to users quickly and reliably. It is about reducing the time and effort it takes to get code from development to production, while also maintaining high quality and stability.

Illustration: CI/CD

The opposite of CI would involve a disjointed and sporadic approach to integrating code changes. Instead of integrating code changes frequently and systematically, developers would work in isolation on separate branches for extended periods, without merging their changes with the main codebase. This lack of integration could lead to conflicts and errors being discovered late in the development process, resulting in a more chaotic and unpredictable software development lifecycle.

Similarly, the opposite of CD would entail a manual and infrequent deployment process. Rather than automating the process of building, testing and deploying software to production environments, updates and releases would be performed periodically and with manual intervention at each step. This could result in longer lead times for delivering new features or updates to users, as well as a higher risk of regression errors or inconsistencies in the deployed software.

In total, the opposite of CI/CD would involve a fragmented and inefficient approach to software development and deployment, characterised by siloed work practices, manual processes and a lack of systematic integration and delivery mechanisms.

CI/CD Pipeline

In the context of CI/CD, a pipeline refers to a series of automated steps or stages that code changes go through from development to deployment. Think of it as a streamlined pathway that code travels along, with each step serving a specific purpose in the software development lifecycle. Here is a breakdown of what a typical CI/CD pipeline might look like:

• Source control
• Build
• Automated test
• Static code analysis
• Deployment
• Manual approval (optional) – in some cases, there may be a manual approval step where a human reviewer verifies that the changes are ready to be deployed to production
• Release to production

The CI/CD pipeline automates these steps, allowing for rapid and reliable delivery of code changes from development to production. Each stage of the pipeline contributes to the overall goal, ensuring that software changes are consistently validated and delivered efficiently.

CI/CD and Project Methodology

Is CI/CD applicable to waterfall?

While CI/CD is mostly associated with agile development due to their shared principles of iterative development and continuous improvement, CI/CD practices can still be beneficial in a waterfall development process, although their implementation may differ:

• In a waterfall process, where development typically occurs in discrete phases (requirements, design, implementation, testing, deployment), CI can still be applied within some phases. For example, developers can integrate their code frequently within the implementation phase, ensuring that any conflicts or errors are detected early. However, the frequency of integration may be less compared to agile projects.

• While the concept of continuous delivery may seem at odds with the sequential nature of waterfall, aspects of CD can still be incorporated. For instance, automating build and deployment processes can help streamline the release process, even if releases occur less frequently than in agile projects. Additionally, automated testing can be utilised to ensure the quality and reliability of the software throughout the development lifecycle.

CI/CD practices may require adaptation to fit within a waterfall development process, but they can still bring benefits such as improved collaboration, faster feedback and more reliable releases, including the constraints of the waterfall methodology.

How about CI/CD and agile?

The connection between CI/CD and agile development is very strong. Agile promotes iterative development and collaboration, while CI/CD enables rapid iteration and feedback loops through automated integration, testing and deployment processes. Together, they empower teams to adapt to changing requirements, deliver value to customers quickly and foster a culture of continuous improvement.

Illustration: Agile development using CI/CD

It seems agile and CI/CD perfectly fit together, since they are closely connected through their shared emphasis on iteration, collaboration, customer focus and adaptability, all aimed at delivering high-quality software efficiently, effectively and continuously.

CI and CD mutual dependencies

Continuous Delivery (CD) and Continuous Integration (CI) are often used together in modern software development practices, but they are not necessarily dependent on each other. However, it is essential to understand the relationship between them and how they complement each other.

Can you have Continuous Integration without Continuous Delivery?

Yes, it is possible to have CI without CD. CI focuses on the frequent integration of code changes and automated testing, which helps improve code quality and detect issues early. However, CD extends this by automating the entire release process, including deployment to production environments. Even if you have CI in place, you might still have manual steps involved in the deployment process, delaying the release cycle and reducing the ability to deliver software quickly and reliably.

Can you have Continuous Delivery without Continuous Integration?

Technically yes, but in practice it does not make too much sense and it is not recommended, especially in agile development. Continuous delivery relies on automation and the ability to reliably build, test and deploy software at any time. Continuous integration helps ensure that the codebase is always in a deployable state by continuously integrating changes and running automated tests. Without CI, you might still be able to automate the deployment process, but the risk of deploying faulty code increases significantly. CD without CI would likely involve a more manual and error-prone process for ensuring the stability and quality of releases.

In summary, while CI and CD are often used together and complement each other well, it is technically feasible to have one without the other. However, achieving the full benefits of modern software development practices typically involves implementing both CI and CD together to enable fast, reliable and automated software delivery.

So, when we say continuous delivery in agile development, we should often assume it includes continuous integration.

Conclusion – The Art of Agile and Continuous Delivery

Just as artists strive to express their vision through their artwork, agile teams leverage their creativity and expertise to craft software solutions that resonate with stakeholders and leave a lasting impression on users.

Illustration: Art of software development

Instead of conclusion, let us try to compare agile software development and continuous delivery to art, in three different aspects:

Collaboration

Agile principles and continuous delivery practices emulate the collaboration between artists and their tools. Agile teams act as the creative minds, drawing inspiration from stakeholders and market trends, while CI/CD pipelines serve as the precision tools that execute the vision efficiently. This collaboration results in the seamless translation of ideas into reliable software, similar to artists crafting masterpieces.

Evolution

Just as artists evolve their styles over time, the integration of agile and continuous delivery enables evolution in software development practices. Agile teams experiment, learn and adapt their processes, much like artists refine their techniques to push the boundaries of their craft. The iterative nature of agile development and the automation provided by CI/CD pipelines facilitate this evolution, allowing teams to deliver increasingly refined and innovative software with each iteration.

Value

Like the unveiling of a masterpiece to an audience, the integration of agile and continuous delivery culminates in the rapid delivery of valuable software to stakeholders. Agile teams prioritise customer needs and feedback, while CI/CD pipelines ensure that these needs are met consistently and reliably. This focus on delivering value mirrors the artist’s desire to evoke emotions and create impact through their artwork, resulting in software that not only meets user needs but also inspires and delights stakeholders.