DevOps Classroom Series – 05/Dec/2021 – Direct DevOps from Quality Thought

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