Continuous Integration vs. Continuous Delivery: Key Differences and Making the Move from CI to CD

What Is Continuous Integration? 

Continuous integration (CI) is a development practice where developers integrate code into a shared repository frequently, ideally several times a day. Each check-in is then verified by an automated build, allowing teams to detect problems early. By integrating regularly, you can detect and locate errors quickly, and remove them more easily.

A key component of continuous integration is the use of automated testing. Each time code is committed, it is automatically tested to catch any bugs or issues as early as possible. This not only ensures that the code is functional but also helps to maintain a consistent level of quality throughout the development process.

Another aspect of continuous integration is the use of a shared repository. This is where all the code for a project is stored, and it’s where developers check their code in and out. By having a shared repository, it’s easier for everyone on the team to stay on the same page and avoid any conflicts or inconsistencies.

What Is Continuous Delivery? 

While continuous integration focuses on the early stages of the development process, continuous delivery (CD) takes things a step further. Continuous delivery is a software development discipline where you build software in such a way that it can be released to production at any time.

In a continuous delivery environment, every change to the system is releasable. That means that every change to the code, configuration, database, or environment is put through a rigorous, automated testing process to ensure that it is production-ready. If the change passes all these tests, it can be automatically deployed to production.

A crucial part of continuous delivery is the use of a deployment pipeline. This is a sequence of validations that the software must go through to get from source code to a production-ready release. By using a deployment pipeline, you can ensure that every change is thoroughly tested and validated before it goes live.

It’s important to realize that continuous integration is an essential component of continuous delivery. Any organization practicing continuous delivery must first implement an effective CI system.

This is part of a series of articles about CI/CD.

In this article:

Benefits of Continuous Integration 

Here are some of the key benefits of implementing continuous integration: 

  • Reduces integration problems, allowing developers to deliver software more rapidly. This is achieved by integrating and testing code more frequently, leading to fewer complex, large-scale problems to solve.
  • Improves code quality by using automated testing. By catching bugs and issues early, they can be fixed before they become bigger problems. This ultimately results in more stable and reliable software.
  • Improves collaboration by promoting a more transparent development process. With everyone working from the same shared repository and integrating their code regularly, it’s easier for teams to work together and stay aligned

Benefits of Continuous Delivery 

Here are some of the key benefits of implementing continuous delivery, in addition to continuous integration:

  • Reduces risk by ensuring that every change is releasable. This dramatically reduces the risk associated with deploying new changes to production. There are fewer hotfixes and emergency patches, and more time to focus on innovation.
  • Enables faster feedback cycles by releasing more frequently. This makes it possible to get feedback from users more quickly, and make adjustments based on that feedback. This allows development organizations to be more responsive to user needs and deliver better, more user-focused software.
  • Promotes a culture of accountability. When every change is potentially releasable, there’s a strong incentive to ensure that every change is of the highest quality. This leads to better code, better testing practices, and ultimately, better software.

Continuous Integration vs. Continuous Delivery: 5 Key Differences

1. Scope

Continuous integration (CI) is a practice that encourages developers to integrate their code into a shared repository several times a day. Each check-in is then verified by an automated build, allowing teams to detect problems early. CI focuses on the initial stage of the software development process, aiming to prevent integration problems and improve software quality.

Continuous delivery (CD) extends the principle of CI. It ensures that the software can be released at any time. CD aims to automate the software release process as much as possible, from the initial stages of development to the final stages of production. This means that with CD, every change in the software goes through the entire pipeline and is ready for release.

2. Stages Covered

In continuous integration, the stages covered are relatively early in the software development lifecycle. The primary focus is on the coding stage, where developers write and integrate code into a shared repository. This integration is then validated by automatically building the application and running automated tests, often unit and integration tests.

Continuous delivery covers a much broader range of stages in the software development lifecycle. In addition to the stages covered by CI, CD includes the stages of deployment and delivery. After the coding and testing stages, the application is deployed to a staging or pre-production environment where it undergoes further testing. Once the application has passed these tests, it is ready for release or delivery to the production environment.

3. Human Intervention

In the CI process, human intervention is minimal. The developers’ main responsibilities are to write the code and commit it to the shared repository. After that, the CI tools take over, automatically building the application and running tests to ensure that the code is functional and does not break the existing system.

Continuous delivery, however, requires more human oversight. While much of the process is automated, human intervention is necessary at several stages. For instance, a human must approve the deployment of the application from the staging environment to the production environment. This is to ensure that the application is error-free and fit for release, adding an extra layer of quality control.

4. Tools

Continuous integration processes generally use tools like Jenkins, Travis CI, and CircleCI. These tools help to automate the process of building the application and running tests each time a developer commits code to the repository.

Continuous delivery requires additional tools to manage the later stages of the software development lifecycle. In addition to the CI tools, CD uses tools like Docker for containerization, Kubernetes for orchestration, and Ansible or Chef for configuration management. These tools help to automate the deployment and scaling of applications, making it possible to deliver updates and new features to users more quickly and reliably.

5. Deployment

In continuous integration, the focus is on deploying the application to a test or staging environment. The aim is to ensure that the application works correctly and that all tests pass before the code is merged into the main branch of the repository.

In continuous delivery, the aim is to have the application ready for deployment to the production environment at any time. This means that after the application has been tested and validated in the staging environment, it is deployed to the production environment where it is made available to end users.

What Is Needed to Graduate from CI to Full CI/CD?

Ultimately, CI vs. CD is not an either or choice. The question is whether your organization practices only basic CI, or is ready to ‘graduated’ to full blown continuous delivery.

Transitioning from Continuous Integration (CI) to a full Continuous Integration/Continuous Delivery (CI/CD) framework involves several critical steps and considerations. It’s not just about implementing new tools but also about adapting the organizational culture and practices. 

Here are the key components required for this transition:

  1. Advanced automation: While CI focuses on automating the integration and testing of code, CI/CD requires extending this automation to the entire software release process. This includes automated deployment and rollback strategies, ensuring that software changes can be pushed to production or reverted with minimal human intervention.
  2. Extended testing framework: To ensure that software can be deployed at any time, a more comprehensive and robust testing framework is necessary. This includes a combination of unit, integration, system, and acceptance tests. Automated testing should cover not only the code but also the environment and configuration changes.
  3. Enhanced collaboration and communication: CI/CD requires a culture of constant collaboration and communication across development, operations, and quality assurance teams. This includes implementing practices like DevOps, where the barriers between different teams are broken down, and everyone works towards a common goal of frequent, reliable releases.
  4. Configuration management: Efficient management of configurations and dependencies is vital. Tools like Ansible, Chef, or Puppet can be used to manage infrastructure as code, ensuring that all environments are consistent and any changes are trackable and reversible.
  5. Environment management: Seamless environment management is crucial for CI/CD. This includes having the capability to replicate production environments in staging or testing phases to catch issues before they reach production. Containerization tools like Docker and orchestration tools like Kubernetes play a significant role in this aspect.
  6. Monitoring and feedback loops: Continuous monitoring of applications and infrastructure is essential to identify and resolve issues quickly. Effective monitoring coupled with feedback loops helps in proactively addressing potential problems, enhancing the reliability and stability of releases.
  7. Continuous improvement: CI/CD is an ongoing journey. Regularly reviewing processes, tools, and practices, and making improvements based on feedback and metrics, is crucial for the evolution and success of the CI/CD implementation.

Related content: Read our guide to CI/CD as a service

CI/CD for Kubernetes with Spot by NetApp

Continuous Delivery has entered a new phase as more and more applications are migrating to microservices, with Kubernetes as the container orchestrator of choice for many. Kubernetes enables agility and faster software development cycles, but as release frequency increases, supporting delivery at large-scale becomes complex and inefficient. 

Spot by NetApp introduced Ocean CD as part of the Ocean suite for Kubernetes to address the specific challenges of modern delivery release cycles. Ocean CD provides complete deployment and verification automation in one fully managed solution, making it easy for users to execute deployments with high confidence. Key features of Ocean CD include:

Out-of-the-box progressive delivery strategies 

Canary and blue/green strategies are easy to define, automate and customize. Developers commit code, use any CI tool and Ocean CD detects the deployments, automatically initiating the assigned rollout strategy. 

Continuous verification automation

Ensure stability and quality of deployments even as release frequency increases. Routine verifications of deployments are conducted automatically and based on metrics from monitoring tools like DataDog and New Relic. 

Automatic rollback 

When issues are detected, Ocean CD initiates safe rollbacks and automatically tunes infrastructure to meet changing requirements of workloads. Continuous improvements are made to application deployments based on metrics collected during verification processes. 

To learn more about Ocean for Continuous Delivery read our blog post or visit the product page