What is CI/CD? A Complete Guide to CI/CD

Software development cycles have changed immensely in the last ten years. New practices and design philosophies are being tried every day. One of these practices is CI/CD pipelines, utilizing aspects of agile software development paired with automation and robust testing.

In this post, we’ll be covering all aspects of CI/CD, as well as some popular CICD tools your organization can use to implement a CI/CD pipeline.

What is CI/CD?

CI/CD is a relatively new practice that combines two approaches to software engineering: Continuous Integration (CI), and either Continuous Integration or Continuous Delivery (CD). It’s done by enforcing automation when building, testing, and deploying applications.

This approach to DevOps CI CD brings constant updates and testing to a product or software, with steps along the way to ensure that development runs smoothly. With these practices in motion, a team can:

• Increase productivity by having frequent code base commits, automated building, and more.
• Increase their chances to find bugs early in development by integrating automated testing, as well as testing during development.
• Send out faster releases thanks to the frequent testing and automated deployment system.

Continuous Integration

The first half of CI/CD is always known as Continuous Integration. It's a set of best practices and procedures that help developers work on smaller changes, as well as utilizing version control to make sure everyone is on the same build.

Developers will build, run, and test code on their own before committing to a central repository. Once those changes have been committed, the new version is built and tested automatically, before delivering a report of details to follow up with. If anything fails, it goes back to the team to be fixed.

A team practising CI successfully are typically all pushing new code to a master branch daily, with each commit triggering tests to be run. If the tests fail, the team can work on a solution quickly and commit again.

CI requires a consistent way to build, package, and test an application through automation. Using this can lead to more collaboration and better quality code, as teams are more likely to commit changes earlier and more often.

Continuous Delivery

One of the two latter halves of the practice, Continuous Delivery stacks on top of CI’s constant commits that newly tested code from CI. It automates the delivery of valid code to a repository, which can then be used to be pushed to production or to users for additional testing. However, this does not send these updates to a final production build, though it is treated as if it was a release candidate.

This is sometimes seen as a “middle step” between Continuous Integration vs Continuous Deployment, the other representation of CD. Not all workflows use all three, and some opt to use one over the other.

Continuous Deployment

Directly opposite of Continuous Delivery, this step is where features that have been thoroughly tested through CI are deployed to a final product via an automated service. This contrasts to Continuous Delivery as it immediately deploys the code as a release candidate.

When in practice, this means that changes in an application can go live within minutes, making it much easier to receive customer feedback. However, it strongly relies on proper and accurate testing during the other steps of the development cycle, meaning it can be costly to set up.

The top CI/CD Tools

As the practice of CI/CD becomes more and more widespread, there’s been a number of solutions to hit the market and aid teams. Naturally, there are a wide number of options with their own pros and cons to each of them. This list will include some of the most popular ones out there, and why they’re excellent.

Jenkins

By far the most popular tool out there, Jenkins has been around for a while. It’s an open-source solution for CI/CD that works on almost all OS, and over 1500 plugins available to work with other tools. It supports many popular testing frameworks, can run testing scripts automatically, and much more. However, the design is fairly developer-centric and can lead to a steep learning curve.

CircleCI

Another heavy hitter, CircleCI offers a lot of the same options as other CI tools, but it’s a little easier to manage. It’s entirely cloud-based, so there’s no need to spend a long time getting it set up. However, some users have reported issues with response time and uptime. This is mainly due to its AWS infrastructure so it’s not entirely their fault.

TravisCI

While not as popular as its friend Jenkins, TravisCI has been a mainstay in the open-source community, mainly because it provides free services for open-source software. It supports a wide variety of languages and is easy to set up and deploy. However, it seems to have fallen out of favour in recent years and is not as popular or robust as other tools.

GitLab

Not just a code repository host, GitLab offers a full suite of DevOps solutions including a CI/CD pipeline for any business. It also features integration with other tools such as Jenkins, so you aren’t fully reliant on one solution at all times.

Bridging the Gap

Not all organizations can utilize a CI/CD pipeline in their workflow, but the impact it has made is significant. It’s become a crucial part of today’s DevOps and continues to shape the industry. If your organization needs to deploy software quickly and efficiently, then CI/CD is an easy solution that will make great improvements to your team.