What is Pipeline - A pipeline is a collection of steps or jobs interlinked in a sequence.

Declarative: Declarative is a more recent and advanced implementation of a pipeline as a code.

Scripted: Scripted was the first and most traditional implementation of the pipeline as a code in Jenkins. It was designed as a general-purpose DSL (Domain Specific Language) built with Groovy.

Why you should have a Pipeline

The definition of a Jenkins Pipeline is written into a text file (called a Jenkinsfile) which in turn can be committed to a project’s source control repository.
This is the foundation of "Pipeline-as-code"; treating the CD pipeline as a part of the application to be versioned and reviewed like any other code.

Creating a Jenkinsfile and committing it to source control provides a number of immediate benefits:

Automatically creates a Pipeline build process for all branches and pull requests.

Code review/iteration on the Pipeline (along with the remaining source code)

Pipeline syntax

  pipeline {
      agent any 
      stages {
          stage('Build') { 
              steps {
                  // 
              }
          }
          stage('Test') { 
              steps {
                  // 
              }
          }
          stage('Deploy') { 
              steps {
                  // 
              }
          }
      }
  }

Task: Realtime example

Let's create a Pipeline project.

Navigate to the Jenkins home page. Create a new Job and select Pipeline.
Now configure the project with valid description.

Now, navigate to the Pipeline section to write the groovy pipeline code.

Here we are writing a simple code to print "Hello Abhishek "

COPY
 pipeline {
     agent any

     stages {
         stage('Jenkins for DevOps') {
             steps {
                 echo 'Hello Abhishek'
             }
         }
     }
 }

Click on Save and then build now.
You can check the details regarding the time of execution.

Let's see the output.

...

Day 26 Task: Jenkins Declarative Pipeline

Why you should have a Pipeline

Pipeline syntax

Task: Realtime example