In this article, we will talk about Jenkins and some of its industry use cases.
Generally, a product development workflow has three key stages: building/compiling the code, testing the build, and finally deploying the application. The application is highly susceptible to changes in the source code. Jenkins and other CI(continuous integration) tools along with SCM tools(Git and GitHub) are used to help overcome this challenge and automate all the stages of the above workflow.
What is Jenkins?
Jenkins is an open-source automation server to perform CI and build automation. Its most atomic function is to execute a set of predefined tasks called jobs. That is every change in the source code triggers a list/pipeline of jobs that accomplish what we do manually. Each phase is monitored and allows you to stop the entire process and the change will be reported to the user by Jenkins. In large companies, it is common for multiple teams to work on the same project without knowing what the other teams are doing on the same code base which is commonly referred to as silos. Those changes can create bugs that will only be revealed when both codes are integrated into the same branch. Since Jenkins can run its predefined jobs for every commit, it will be able to detect and notify developers that something is not right and where it is.
It can be installed through native system packages, Docker, or be run by any machine with a Java environment installed. Thousands of add-ons/plugins can be integrated with Jenkins, they provide support for different types of build, version control systems, automation, and more.
Jenkins is often used for building projects; running tests to spot bugs, analyze static code, and deployment. It also executes repetitive tasks, saves time, and optimizes developing processes.
Beginning with the second version, Jenkins introduced pipelines, a different way to programmatically define a project build workflow. Before pipelines, the CI description was defined and stored outside the repository — it was designed to evaluate — now, with Pipelines, CI files are present in project source code. The file describes the workflow through a language that can be used to create different jobs in sequence or in parallel.
Jenkins use cases
Let’s take a look at some of the important use cases Jenkins plays a critical part in.
Continuous Integration (CI)
Continuous integration is a practice that forces developers to frequently integrate their code into a central repository. Instead of building out new features to the end without any quality measurement, every change is tested against the central repository in order to anticipate errors.
Every developer commits daily to a shared mainline and every commit triggers an automated process to build and test. If building or testing fails it can be detected and fixed within minutes without compromising the whole structure, workflow, and project. In that way, it is possible to isolate problems, solving them faster and provide higher-quality products.
Continuous Delivery (CD)
Continuous delivery is the ability to make changes of all types — such as new features, configuration changes, error fixes, experiments — into production in a safe and efficient manner using short work cycles.
The main goal of continuous delivery is to make deployments predictable as routine activities that can be achieved upon request. To be successful, the code needs to always be in a deployable state even when there is a scenario with lots of developers working and making changes on a daily basis. All of the code progress and changes are delivered in a nonstop way with high quality and low risks. The end result is one or more artifacts that can be deployed to production.
Continuous Deployment (CD)
Continuous deployment, also known as continuous implementation, is an advanced stage of continuous delivery that the automation process does not end at the delivery stage. In this methodology, every change that is validated at the automatic testing stage is later implemented at the production stage.
The fail-fast strategy is always of the utmost importance when deploying to production. Since every change is deployed to production, it is possible to identify edge cases and unexpected behaviours that would be very hard to identify with automated tests. To fully take advantage of continuous deployment, it is important to have solid logging technology that allows you to identify the increasing error count on newer versions. In addition, a trustworthy orchestration technology like Kubernetes will allow the new version to slowly be deployed to users until the full rollout or an incident is detected and the version is cancelled.
As a job executor, Jenkins can be used to automate repetitive tasks like backup/restore databases, turn on or turn off machines, collect statistics on a service and other tasks. Since every job can be scheduled, repetitive tasks can have a desired time interval (once an hour, once a week, etc…).