Understanding Jenkins Declarative Pipeline

Jenkins, a popular open-source automation server, offers various features to streamline the Continuous Integration and Continuous Deployment (CI/CD) processes. One of the key features that Jenkins provides for defining these processes is the Declarative Pipeline. In this blog post, we'll explore what a pipeline is, delve into the Declarative Pipeline, and understand why adopting it is beneficial for your software development workflow.

What is a Pipeline?

In the context of Jenkins, a pipeline is a collection of steps or jobs that are interconnected in a sequence to automate the software delivery process. It allows developers and DevOps teams to define, orchestrate, and visualize the entire build, test, and deployment workflow.

Declarative vs. Scripted Pipeline

Jenkins initially introduced the Scripted Pipeline, a traditional implementation of the pipeline as code using Groovy. It provided a versatile scripting language for defining pipelines. However, as the need for more structure and simplicity arose, the Declarative Pipeline was introduced. The Declarative Pipeline is a higher-level abstraction with a more human-readable syntax, making it easier to understand and maintain.

Why You Should Have a Pipeline

The Jenkins Pipeline, defined in a text file known as a Jenkinsfile, is the cornerstone of "Pipeline-as-code." This approach treats the continuous delivery pipeline as an integral part of the application, subject to versioning and code review like any other software artifact.

Here are some immediate benefits of using a Jenkins Pipeline:

Automated Build Process: Jenkins automatically creates a Pipeline build process for all branches and pull requests, ensuring consistency across different code branches.
Code Review and Iteration: The Jenkinsfile, representing the pipeline, becomes an essential component of code reviews. Developers can iterate on the pipeline code alongside other source code changes.
Versioned Infrastructure: By treating the pipeline as code, you can version control it and manage changes over time, bringing the same level of discipline to your CI/CD process as you do to your application code.

Declarative Pipeline Syntax

Let's take a brief look at the syntax of a basic Declarative Pipeline:

pipeline {
    agent any
    stages {
        stage('Build') {
            steps {
                // Your build steps here
            }
        }
        stage('Test') {
            steps {
                // Your test steps here
            }
        }
        stage('Deploy') {
            steps {
                // Your deployment steps here
            }
        }
    }
}

In this example:

The agent directive specifies the execution environment for the pipeline.
The stages block defines the different stages of the pipeline, such as Build, Test, and Deploy.
Each stage contains steps, which represent the actual tasks to be performed.

Task 1: Creating a Declarative Pipeline Job

As part of your Jenkins setup, you've created a new job by selecting "Pipeline" instead of a freestyle project. This sets the stage for embracing the power of Pipeline-as-code and streamlining your CI/CD workflow.

1.Pipeline

i. Description

ii. Build Triggers-->None

iii. None

iv. Script--> Hello, world!

v. Pipeline

vi. Select-->logs

vii. Stage Logs

Roming posts, we'll delve deeper into advanced features of the Declarative Pipeline and explore how it can be customized to cater to specific project requirements. Stay tuned for more insights into optimizing your Jenkins pipelines for efficient software delivery.

(Day 26 )Task: Jenkins Declarative Pipeline