One of the most important parts of your DevOps and CICD journey is a Declarative Pipeline Syntax of Jenkins
Some terms for your Knowledge
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-01: Jenkins "Hello World" Declarative Pipeline
- Create a New Job, this time select Pipeline instead of Freestyle Project.
Click on "New Item" to create a new Jenkins job.
Enter Job Details:
Provide a name for the job (e.g., "HelloWorldPipeline").
Choose "Pipeline" as the job type.
Configure Pipeline: In the pipeline configuration section:
Choose "Pipeline script" from the "Definition" drop-down.
In the "Pipeline" section, you can directly enter the Declarative pipeline script.
Add Declarative Pipeline Script: Use the following example as your Declarative pipeline script:
pipeline {
agent any
stages {
stage('Hello') {
steps {
echo 'Hello World!'
}
}
}
}
Save and Run:
Click on "Save" to save your pipeline configuration.
Run the pipeline job by clicking on "Build Now."
View Console Output: After the build completes, you can click on the build number to view the console output. You'll see the output "Hello World!" printed as part of the pipeline execution.
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