DevOps Classroom Series – 25/Jul/2021

Jenkins Continued

• Build Environment
• Build
• After the build is finished, the steps which we want to perform are called as post build actions.
  • Build might be failed
  • Build might be success
  • Build might be aborted
• Archiving the artifacts:
  • Using this we can archive the build artifacts that can be dowloaded for the jenkins ui directly
• Publishing the Junit test results:

Configuring Email Notifications in Jenkins

• For the lab setup we will be using mail trap which is simulated smtp server Refer Here
• Navigate to Manage Jenkins => Configure System

Exercise – 1

• Create a Jenkins job to build a java project openmrs Refer Here.
• You need to archive the openmrs war file and publish junit test results
• Also send email notification when the build is unstable.
• For configuring the test reports from any folder use the following expression for configuring the junit test results

**/TEST-*.xml

Problems with Free Style Projects

• The build steps are configured in external jenkins jobs
• Changes in the build steps are not version controlled.

Jenkins 2

• Jenkins in its newer versions started supporting pipelines-as-code feature.

• We write the build steps or the whole pipeline in a text file generally Jenkinsfile

• This Jenkins file will be part of the code

• Jenkins 2 supports two kinds of pipelines

  • Scripted Pipeline
  • Declarative Pipeline

• With Jenkins 2 the new Job Types are added

  • Pipeline
  • Folder
  • Organization
  • Multibranch Pipeline

Syntax: Scripted vs Declarative Piplelines

• Scripted referes to the initial way that pipelines-as-code have been done in Jenkins
• Scripted syntax relies heavily on the Groovy Language and Groovy constructs for things like error checkings and dealing with exceptions
• Declarative syntax is the newer option. This is Jenkins DSL

# Scripted Pipeline
node('GOL') {
    stage('SCM') {
        // clone the code
        git 'https://github.com/asquarezone/game-of-life.git'
    }
    stage('build') {
        // build the code
        sh 'mvn package'
    }
}

# Declarative Pipeline

pipeline {
    agent { label 'GOL' }
    stages {
        stage('SCM') {
            steps {
                git 'https://github.com/asquarezone/game-of-life.git'
            }
        }
        stage('COMPILE'){
            steps {
                sh 'mvn package'
            }
        }
    }
}

• Advantages of Scripted Pipeline
  • Generally fewer section and less specification needed
  • Capability to use more procedural
  • More like creating a program
  • More flexible to do custom operations if needed
  • Ability to model more complex workflows and pipelines
• Disadavantages of Scripted Pipeline
  • More programming required
  • Syntax checking limited to Groovy Language and environment
  • Further away from traditional Jenkins model
• Advantages of Declarative Pipeline
  • More Structure – close to traditional sections of Jenkins web forms(free style project)
  • More capability to declare what is need, so more readable
  • Can be generated from Blue Ocean Graphical Interface
  • Better syntax check and error identification
• Disadvantages of Declarative Pipeline
  • Less support for iterative logic
  • Still evolving
  • More rigid structure(harder to handle customizations)
  • Not suite for complex pipelines and workflows

Foundations

• Jenkins Master
• Node
• Agent
• Executor