Continuous Integration vs. Continuous Delivery vs. Continuous Deployment

Before diving onto various DevOps concepts, we need to figure out what “continuous” means in the DevOps environment. Basically, the term “continuity” refers to software changes that occur throughout the software development process.

And of course, there is some trickery in the term “continuous”.

In fact, after the implementation of the functionality, it may take some time before you release the code to production, but this time is still much less than it was before the advent of the DevOps culture.

Continuous Integration (CI), Continuous Delivery (CD), and Continuous Deployment (CD) are integral parts and foundation of the DevOps approach to software development and upgrading, which implies continuous, pipeline testing, build, delivery, and deployment of updates. Both eparate use the components of this approach (CI or CI + CD) and their sequential use within a single process (CI + CD + CD), are possible since the goal pursued by CI/CD is to get high-quality code in a short time.

When an organization is constantly changing and becoming the norm, software development cycles become more frequent. By using CI/CD processes in software development, more frequent updates can be released on an ongoing basis without loss of quality.

The ideal process looks something like this:

• the developer pushes the code to the central storage;
• on the continuous integration server, changes are merged with the main code, unit tests are implemented and everything is uploaded to the staging environment;
• Quality Assurance engineers test the application in the continuous delivery environment;
• then everything is checked for release to production;
• deployment to production.

Continuous Integration, Delivery and Deployment significantly accelerate the software delivery without compromising on product quality. By automating the process, CI/CD provides rapid user feedback loops and thus aligns with the practices followed by Agile development teams.

WHAT IS CONTINUOUS INTEGRATION?

Continuous Integration is a software development practice that requires developers to upload code to central storage on a regular basis, several times per day.

Each code update is then validated with automated tests, allowing the development team to identify integration issues at an early stage. This allows independent development teams to spend less time looking for problems in the code and more time creating new features.

CONTINUOUS INTEGRATION PROCESS

Developers write code in their own separate branches and then push the results to central storage. Automated unit and integration tests are implemented – based on their results, errors and other code quality issues are revealed. After successfully passing the automated tests, developers can view the changes in the shared code branch and create pull requests. This mechanism allows individual developers to directly review and propose changes in the main branch of the code created by other developers working on the project.

Once the review process is complete and the new code is merged with the main branch, the cycles of further review and bug fixing continue on the basis of the integrated main branch. This often happens several times a day, especially in a large team where everyone is working on many smaller tasks. In this case, everyone is working with the same version of the code. The divergence of code versions and the related issues that may arise due to the desynchronization of developers’ actions are significantly reduced or disappear.

CONTINUOUS INTEGRATION: HOW EVERYTHING WORKS

It remains to figure out how the Continuous Integration process takes place. The system itself does not collect or test the code. This is done by other machines – computers or virtual servers, so-called “agents”.

• Continuous Integration systems have a server and a client. The server is directly the part that is available to the development team, a convenient interface where they can evaluate how successful the build and tests were.
• The “client” is installed on “agent” machines or virtual servers.
• When the server receives a command, it searches for a free “agent” and gives it instructions on what to do, what tests to conduct.
• The “agent” carries out all this, generates the results and sends them back to the server.
• The server formalizes everything and shows it to those who need it or sends them letters.

It is important that the user always see which machine has done all the work at any given moment. The users can choose themselves the “agent” for the build and tests.

BENEFITS OF CONTINUOUS INTEGRATION

• You can identify problems at an early stage and fix them before merging new code into the main branch, effectively maintaining current product health.
• Communication between the team is improved due to complete real-time visibility.
• Bugs can be found faster.
• No need to sit and wait for the code test to finish. You can work on a new piece.
• A lot of feedback on the changes. This will help improve the product.

SYSTEMS FOR CONTINUOUS INTEGRATION

As we mentioned above, there are quite a few systems for continuous integration. Consider the features of those that are used most often.

• TeamCity – this service supports a lot of powerful functionality. There is a free version for small projects. The service has clear integration with control systems, is highly reliable, and does not depend on the launch of the build. You can run commands remotely.
• Jenkins – is an open-source Java tool. You can test the code in real-time, generate reports on individual changes in the codebase. It is suitable for quick markings and fixes of errors and bugs in the code. Jenkins is easy to set up and is available on Linux, Mac and Windows.
• Codeship – is a continuous integration tool that automates development and deployment. It allows you to customize the access levels of team members for each project. There is a debugging function right from the continuous integration environment and it also has a convenient toolbar.
• Travis – is a web resource. It can be used free of charge for open-source projects and supports quite a few programming languages, including Node and PHP. Easily customizable, it integrates with Slack, HipChat, email and uses virtual machines for a build. It is possible to run parallel testing.

Additional reading: What Are NoSQL Databases and Why Enterprises Rely on NoSQL?

WHAT IS CONTINUOUS DELIVERY?

Continuous Delivery is a process in which changes to the code automatically lead to a new build, testing, and preparation for release. As a result, the created software can be sent to production at any time.

Continuously integrated new pieces of code are further tested for performance and functionality until they are approved by developer reviewers for inclusion in the main branch of the code. For the reliable and smooth functioning of the continuous delivery process, the foundation in the form of an efficient continuous integration process is very important. When implemented correctly, developers will always have a ready-to-deploy version of the build that has gone through a standardized testing process.

The process begins when the developer pushes the written code to the storage and ends when testing is complete so that the code is fully ready for deployment in a production environment. If any errors or bugs occur during automated testing, the CI tool will automatically notify the developer via email or SMS.

Continuous delivery usually includes a staging environment, namely an environment that is as close to production as possible but without actual data, where changes are made manually before the production release. The decision on readiness and production is more a business decision than an IT decision.

BENEFITS OF CONTINUOUS DELIVERY

• Reducing risks. Some tasks such as testing the application in different versions of different browsers can be automated to reduce the risk of errors.
• Fast time to market. Errors in the code are detected at an earlier stage and can be quickly eliminated, which leads to an increase in the speed of delivery.
• One source. All members of the development team use the same central storage to write their code. It is always known what changes were made and by whom.
• Reducing the backlog. CD reduces the number of small defects in the backlog as these are already known in advance and fixed before release.
• Customer Satisfaction. Continuous delivery allows you to receive real-time feedback, as well as promptly correct team miscalculations. With this approach, new product development will be more advanced and more in line with the expectations of the end-user.

WHAT IS CONTINUOUS DEPLOYMENT?

Continuous Deployment is very similar to continuous delivery. The only difference between the two is that with continuous deployment, any added piece of code that passes all the automated testing steps will be immediately released to production.

Continuous Deployment does not require any additional manual testing in a staging environment, as automated testing is performed in the preceding phases. However, it calls for a high culture of monitoring, being on-call and recovery.

Both continuous delivery and continuous deployment rely heavily on infrastructure readiness and application monitoring to detect any issues as soon as possible that were not identified in the feedback loops during the testing phases, since there is no manual verification involved. Continuous Deployment strategies typically involve incremental deployments that enable testing changes incrementally.

BENEFITS OF CONTINUOUS DEPLOYMENT

• Enhancing overall productivity and workflow management.
• Continuous deployment workflow ensures accelerated software delivery.
• Reducing Continuous Delivery DIYing and increasing the focus on the product.
• Automation of repetitive manual tasks and greater focus on testing.
• Frictionless deployments without compromising on security.
• Connecting a variety of software development tools and technologies into a smooth product stream workflow.
• Integrating teams and processes with a unified pipeline.
• Providing a high-level view across all applications and development environments.
• Shipping both cloud-native and traditional applications in a unified pipeline.

CONTINUOUS INTEGRATION VS CONTINUOUS DELIVERY

So what’s the difference between Continuous Integration vs Continuous Delivery? Let’s sum up:

• While Continuous Integration suggests testing every change to product code automatically, Continuous Delivery is an approach to get changes of new features, configuration, and bug fixes.
• CI uses unit tests, on the other hand, Continuous Delivery utilizes business logic tests.
• While CI refers to the versioning of code, Continuous Delivery is the logical evolution of CI.

CONTINUOUS INTEGRATION VS CONTINUOUS DEPLOYMENT

Now, let’s take a closer look at Continuous Integration vs Continuous Deployment:

• While Continuous Integration is meant to automatically test each change to the codebase, Continuous Deployment is an approach to develop software in a short cycle.
• Continuous Integration is performed right after the developer checks in. In Continuous Deployment, the deployment process takes place at the production stage (direct deployment).
• While Continuous Integration uses unit tests and Continuous Delivery utilizes business logic tests, both testing strategies are used in Continuous Deployment.
• Continuous Integration is the versioning of source code and Continuous Delivery is its logical evolution, however, Continuous Deployment means automated implementations of the source code.

CONTINUOUS DELIVERY VS CONTINUOUS DEPLOYMENT

What is the difference between Continuous Delivery and Continuous Deployment?

• While Continuous Deployment focuses on productive development, Continuous Delivery focuses on the release and release strategy.
• In Continuous Delivery, the code is continuously delivered until the Dev teams consider it is ready to ship. On the other hand, in Continuous Deployment, developers deploy the code right to the production stage.
• While Continuous Integration utilizes unit tests, both unit tests and business logic tests are used in Continuous Deployment.

CONCLUSION

Moving to Continuous Integration and Continuous Delivery can significantly improve the software development process, help effectively tackle integration challenges and create a stable, safe and quality product.

WHAT DEVCOM CAN OFFER

Delivering DevOps-as-a-Service is one of DevCom’s core areas of expertise. Our DevOps experts can assist you in implementing technology and organizational changes to reduce software time-to-market, eliminate defects, and reduce risk by implementing DevOps.

We use modern development practices, cloud features, and innovative development pipeline toolsets to design, implement, and manage cost-efficient cloud infrastructure along with Continuous Integration and Continuous Delivery of new software code and automation of workflows.

The DevCom DevOps team can help you with maintaining consistency in your software deliveries, improving the productivity of your teams, reducing complexities associated with managing your systems, enhancing your IT systems and streamlining your processes, resolving the problems as and when they occur, automating your routine repetitive tasks.

• From code to cloud, we automate each part of the DevOps process with CI/CD and your choice of tooling.
• Build and re-architecture CI/CD pipelines, establishing environments for application,
• CI/CD pipelines and releases with multiple environments,
• Workflows automation with TeamCity and GitHub Actions,
• Host Jenkins workloads, extend existing configuration, or simplify CI/CD with Jenkins plugins,
• Fast and repeatable deployments.

Request our comprehensive DevOps services now.

Request our comprehensive DevOps services now.

Written by: Liza Hazevych, Marketing Manager at DevCom.