Understanding the basics of the Jenkins Pipeline

Jenkins, the heart of DevOps, is a continuous integration tool that allows developers to integrate code into a shared repository at regular intervals. The usual practice is to trigger a build as soon as the code is committed to the repository.

If you’re worried about Jenkins replacing Hudson, we can assure you that Hudson is still available as a managed project by Oracle. In fact, Jenkins was forked from the Hudson source code and later began to be supported by the open community.

The common process of Jenkins involves the following 3 steps:

Developers make changes to the code and commit it to their repository.

Jenkins picks up the code and later runs builds and any tests that may be required.

As a post step, notifications can be triggered, logs can be checked, or any other cleaning job can take place.

Any event mapped above, is taken care of by a Jenkins job. A Jenkins job is simply a process that runs on Jenkins server to provide the above mentioned functionality.

If you’re new to Jenkins, we’re going to help you understand the basics of the Jenkins pipeline, along with the functionality aspect of Jenkins.

Jenkins Pipeline

Jenkins pipeline allows us to define a complete list of events that happen in the code lifecycle. Starting from the build, to testing and deployment.

We can use a set of plugins that help in the implementation of certain processes as a continuous delivery pipeline. Where pipelines are defined using code by using groovy language to define the processes that would run in the pipeline.

To implement pipeline as code, a Jenkinsfile needs to be present at the project’s root repository.

Jenkins file supports two different syntax:

Declarative

Scripted

Declarative pipeline was a recent release and provides better syntax support over the scripted pipelines.

Here’s why you should use Jenkins pipeline:

Pipeline can be run in a loop.

It supports larger projects that may involve a high CPU job, provided the Jenkins infrastructure is scalable enough to support it.

Since Jenkins pipeline is written in code, any number of users can use it as a template, modify it and run customized tests and processes.

Multiple jobs can run parallely.

Jenkins Pipeline is robust. Pipeline can automatically be resumed from it might have stopped for any reason.

Understanding the pipeline

Pipeline

A user-defined block, which contains all the processes such as build, test, deploy, etc. All the stages and steps are defined in this block.

Node

The node is a machine on which Jenkins runs. A node block is used in scripted pipeline syntax.

Stage

This block contains a series of steps in a pipeline. i.e., build, test, deploy processes on a stage.

Let us see an example for multiple stages, where each stage performs a specific task:

Step

A step is a single task that executes a particular process at a defined time. A pipeline involves steps defined within a stage block.

Defining a Jenkins pipeline

The following steps run smoothly once you have the initial configuration and installations complete for Jenkins.

1. For Jenkins Pipeline, install the Pipeline plugin.

Go to Manage Jenkins > Manage Plugins >Available section> Search Pipeline.

If you are already installed Pipeline It will display in the Installed section.

Create a new project with the Pipeline.

2. Go to Jenkins Home > New Item > Create Project with Pipeline.

After creating Pipeline Project the following window should appear:

This is where we write pipeline code.

The two options seen in the image are as follows:

Pipeline Script: Write the Pipeline directly on Jenkins.

Pipeline Script from SCM: Write Jenkinsfile and upload it on any SCM and then use it from that repository.

Conclusion

Training and testing is a crucial aspect of the Software Development Life Cycle. Jenkins Pipeline helps you test your software pipelines without any hassle. And now training has become a part of Engati’s culture, and we extend this to our clients by providing a training module for chatbots to guarantee customer satisfaction.

Register with Engati to learn more.

Originally published here.