Welcome to Day 26 of the 90 Days of DevOps challenge! 🎉 Today, we’ll delve into Jenkins Declarative Pipeline, an essential aspect of modern CI/CD practices. Declarative pipelines offer a more structured and user-friendly approach to defining Jenkins pipelines, making them a crucial tool in your DevOps toolkit.

Understanding Jenkins Pipelines

Before we dive in, let’s clarify some key concepts:

• Pipeline: A pipeline in Jenkins is a sequence of steps or jobs linked together to automate the build, test, and deploy processes.

• Declarative Pipeline: This is a more recent and advanced implementation of pipelines as code. It uses a simplified and more structured syntax, making it easier to write and understand.

• Scripted Pipeline: The original implementation of pipelines in Jenkins, using a general-purpose DSL built with Groovy. While powerful, it’s more complex and less user-friendly compared to Declarative Pipelines.

Why Use a Pipeline?

A Jenkins Pipeline is defined in a Jenkinsfile, which can be versioned and reviewed like any other code. This approach, known as "Pipeline-as-Code," provides several benefits:

• Automatic Pipeline Creation: Pipelines are created for all branches and pull requests automatically.

• Code Review: Your pipeline code can be reviewed and iterated upon alongside your application code.

Task-01: Create a Jenkins Declarative Pipeline

1. Create a New Pipeline Job

   • Open Jenkins and click on "New Item."

   • Select "Pipeline" and give your job a descriptive name.

   • Click "OK" to proceed to the job configuration page.

2. Configure the Pipeline

   • In the job configuration, scroll down to the "Pipeline" section.

   • For the "Definition" field, select "Pipeline script."

   • In the "Script" field, enter the following Declarative Pipeline syntax:

       pipeline {
           agent any
           stages {
               stage('Build') {
                   steps {
                       echo 'Building...'
                   }
               }
               stage('Test') {
                   steps {
                       echo 'Testing...'
                   }
               }
               stage('Deploy') {
                   steps {
                       echo 'Deploying...'
                   }
               }
           }
       }
     

   • This script defines a simple pipeline with three stages: Build, Test, and Deploy. Each stage currently includes a placeholder step that outputs a message.

3. Run the Pipeline

   • Save your pipeline configuration.

   • Click "Build Now" to trigger the pipeline.

     

4. Review and Troubleshoot

   • Monitor the build process and review the output of each stage.

   • If you encounter issues, seek help from Jenkins groups, Discord, or Telegram communities.

Conclusion

Today’s task focused on setting up a Jenkins Declarative Pipeline, an essential skill for modern CI/CD workflows. By creating and running a basic pipeline, you’ve taken an important step towards mastering Jenkins pipelines as code.

Feel free to share your progress and any challenges you faced on LinkedIn with #90DaysOfDevOps Challenge. Happy learning and keep pushing forward! 🚀