What is Continuous Delivery?

Part of the Continuous Integration/Continuous Delivery Pipeline (CI/CD Pipeline), continuous delivery (CD) is an automated software delivery process centered around improving the speed with which development teams create and release new features to end-users. The other parts of the CI/CD Pipeline are continuous integration and continuous deployment. But what is continuous delivery exactly, and how is it different from the other two continuous parts of the pipeline?

The central idea behind CD is to be able to release the software’s current version directly to the production environment and end-users at any time. The continuous delivery process has two main prerequisites: first, everyone involved in delivery must work closely together — this is frequently called implementing DevOps practices — and second, as much of the delivery process as possible must be automated.

Key Principles of Continuous Delivery

DevOps Practices: DevOps merges software development practices (Dev) and IT operations (Ops) to shorten the development lifecycle and provide continuous, high-quality software. DevOps practices enhance collaboration between teams that traditionally worked in silos. DevOps is achieved by streamlining workflows, merging responsibilities, and integrating toolchains, collectively improving software delivery speed and quality. DevOps emphasizes a culture of continuous improvement, enabling teams to adapt to changes rapidly. By implementing DevOps within the CD framework, organizations foster an environment where building, testing, and releasing software can happen rapidly, frequently, and reliably.

Automation: The heart of continuous delivery speed. Relying on manual input increases the possibility of errors and often causes unnecessary delays. DevOps practices in general, and CD practices push teams to find ways to automate and optimize as many steps of the process as possible. Through tools like Jenkins, Docker, and Kubernetes, automation allows teams to focus on complex tasks that need human attention. This way, teams can focus on innovation and development rather than spending time on process.

Other Continuous Delivery Principles

Rapid Feedback Cycles: The CD process emphasizes rapid feedback cycles to identify and address issues quickly. Regular integration and automated testing frameworks like Selenium, playwright, and JUnit provide immediate feedback, enhancing code quality and reducing error resolution time.

Shift-Left Testing: Shift-left testing is integration testing earlier in the development process. It promotes early debugging and quality enhancement. Analysis of early testing metrics also encourages ongoing collaboration among developers, testers, and operations teams, ensuring quality is part of every step of production.

The Other Parts of the Pipeline

As discussed, continuous delivery is part of the CI/CD Pipeline. The pipeline is generally broken down into segments: first, continuous integration, and then either continuous delivery or continuous deployment. Here is a brief overview of the remaining two parts of the pipeline and how they relate to continuous delivery.

Continuous Integration

Continuous integration is simpler to implement and is usually the foundation for continuous delivery and deployment. Where delivery and deployment are both software release processes, continuous integration is a software development process that happens before deployment.

The primary role of continuous integration is to integrate/merge branched source code into a common codebase. An application with too many long-lived feature branches can become difficult to manage. By practicing continuous integration, DevOps teams seek out and resolve merging conflicts early. This process means new functions are less likely to cause problems with existing code because the main truck has been cleaned up.

Key Principles of Continuous Integration

Frequent Code Integration: Continuous integration requires developers to merge their changes back to the main branch frequently, as often as several times a day. This practice reduces integration challenges by identifying conflicts and inconsistencies early, making them easier to address.

Automated Builds and Tests: Automated builds and tests are fundamental to continuous integration. Every code commit triggers an automated build process followed by a series of tests. This automation ensures that the software remains in a releasable state at all times and provides immediate feedback on the system’s health.

Maintain a Single Source Repository: Developers should commit all code to a shared repository managed by a version control system like Git. This central repository ensures that every team member is working with the latest code, reducing the chances of confusion and conflict between different code versions.

Transparent and Accessible Information: Visibility into the development process is a necessity. Continuous integration encourages transparency by using dashboards that display build statuses, test results, and other critical information. This visibility helps teams quickly identify and resolve issues.

Continuous Deployment

Continuous deployment is very similar to continuous delivery. The main difference is that continuous deployment automates the deployment of the new code to the production environment and the end user. For continuous delivery, the process is automated up to the staging environment, and deployment is a manual step.

The benefits of continuous deployment automation include the potential for more frequent releases and quicker end-user feedback.

The main drawback is that without a human QA step, problems the acceptance testing does not discover will not be noticed until after the update has been released.

Continuous Delivery Use Cases

Now that you know what continuous delivery is and how it fits into the CI/CD Pipeline, let’s explore some practical examples of its benefits.

Microservices Architecture

• Continuous delivery excels in environments where applications are broken down into microservices. It allows individual services to be updated independently, enhancing agility and reducing risks associated with deploying large-scale changes.
• Facilitates the rapid deployment of new features or updates to specific microservices without impacting the entire system.

Cloud-Native Applications

• Cloud-native environments benefit from Continuous delivery due to their inherent scalability and flexibility. CD automates the process of pushing updates to these applications, supporting dynamic scaling and provisioning needs.
• Ensures that cloud-native applications can leverage on-demand resource provisioning, enhancing operational efficiency and responsiveness.

Agile Development Teams

• CD supports agile practices by enabling frequent and incremental changes, allowing teams to quickly adapt, optimize, and iterate on software based on user feedback and changing requirements.
• CD promotes a shorter development cycle and quicker feedback loops, pivotal for agile environments.

Automated Testing and Quality Assurance

• Continuous delivery integrates automated tests into the deployment pipeline, ensuring that code changes meet quality standards before they reach production. This reduces the risk of defects and downtime.
• CD helps maintain a high level of software quality and reliability, which is crucial for maintaining user trust and satisfaction.

Software Releases and Feature Rollouts

• Continuous delivery paired with the use of feature flags allows for the staged rollout of features, making it possible to initially release changes to a small subset of users, monitor performance, and then proceed with a full rollout. This is known as progressive delivery.
• Progressive delivery as part of CD reduces the impact of new releases on the production environment, minimizing downtime and improving the user experience.

Compliance and Security Updates

• CD facilitates the swift deployment of security patches and compliance updates, which is crucial for maintaining software products’ security posture.
• CD ensures that updates are deployed as soon as they are ready, reducing the window of vulnerability.
• The extensive automation that CD requires also ensures that every commit, test and deployment action is automatically logged, something that depended upon human discipline when the build and deploy steps were manual.

Development and Operations (DevOps) Integration

• CD enhances collaboration between development and operations teams by automating the deployment process and integrating operations requirements early in the development lifecycle.
• CD streamlines the development process, improving speed and efficiency while reducing the friction typically seen in traditional software deployment scenarios.
• Teams focus on building and refining automation, which scales far better than manual hand-offs and follow-through.