What Is A Jenkinsfile? How To Write One…

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If you know about Jenkins then I am sure you would know about Jenkins pipeline. It is a suite of tasks that are linked to each other and are executed to achieve continuous integration and delivery.

And Jenkinsfile is the heart of this pipeline. It provides Jenkins pipeline a definition, with a text-based file that contains everything that Jenkins pipeline needs to know for its execution.

Jenkinsfile is not the only way to define a pipeline, you can also do it in UI. However, it is a best practice to do it using Jenkinsfile and check in to your SCM.

Here is the most basic pipeline to build, test and deploy software,

pipeline{
	Agent any
	stages{
		stage("build") {
			steps{
				echo"This is the build step"
			}
		}
		stage("test"){
			steps{
				echo"This is the test step"
			}
		}
		stage("deploy"){
			steps{
				echo"This is the deployment stage"
			}
		}
	}
}

Mentioning agent is crucial, as it tells Jenkins to provide a host and workspace for execution.

Steps is where you will mention all the commands that needs to be executed for each stage.

As I said, this is a very basic pipeline and we can do much more than this in Jenkinsfile, such as, using environment variables to add conditions for stages/steps or even create your own variables.

We can also run the stages in parallel instead of sequential to increase the performance of pipeline.

I will be writing an in-depth article in a few days, which will cover all the essentials of Jenkinsfile and how we can use it to achieve CI-CD.

Hope this gave you an overview to Jenkinsfile.

Have a great day 🙂