DevOps Classroom Series – 05/Dec/2021

Declarative Pipeline

• The structural layout of the pipeline project appears as shown below

pipeline
{
    agent any
    stages {
        stage('<name of stage>') {
            steps {
                ...
            }
            post {

            }
        }
        stage('<name of stage>') {
            steps {
                ...
            }
            post {
                
            }
        }
    }
    post {

    }

}

• Visual representation of structure

Triggering Jobs

• In the free style project, we have the following options
• In the Pipeline project jenkins ui shows the following options
• To configure the pipelines in the
  • Free style project: => UI
  • Scripted pipeline, a properies can be specified
  • Declarative pipeline, triggers
• Build after Other projects are built:
  • Freestyle
    • Save the configuration
    • Build the other project
    • Upstream project for this would be starterproject
    • For starter project freestyle project would be Downstream
  • Scripted:
    • Refer Here for the changes done in jenkinsfile
  • Declartive Pipeline:
    • For writing triggers Refer Here
    • Refer Here for the changes done
• Build periodically:
  • In this case we want to trigger the build based on some schedule, and in linux to schedule we have cron job.
  • Jenkins uses this cron syntax to execute the jobs on schedule
  • To understand cronjobs Refer Here
  • Lets try to configure the
    • Free style project to run every 1/2 hour on weekdays (remove the upstream)
    • scripted pipeline to run every 3 hours on weekends (remove the upstream)
      • Refer Here for the changeset
    • declarative pipeline to run every day @ 11:45 PM on week days
      • Refer Here for the changeset
• Poll SCM: In this we can poll the version control remote for changes & when the changes occur, we can trigger the build. But we need to configure how frequently we need to poll the SCM using cron syntax
  • Declarative pipeline: Lets configure for polling scm every 5 minutes
    • Refer Here for the changeset

User Input

• Using this step, we can stop and wait for the user response
• Refer Here
• Refer Here for changes

Parameters

• when we build the project we will have a need to use parameters
• Lets create some parameters for free style project
• Lets create parameters where user will select
  • which branch to build
  • what will be maven goal => default goal is package
  • Now lets use this PARAMETERS in selecting the branch
  • For maven goal
  • Navigate to the project page
• Lets give the same parameters from
  • scripted pipeline: Refer Here for the changes
  • declarative pipeline:
    • Refer Here for the documentation
    • Refer Here for the changes done

Note

• Pipeline steps reference Refer Here