Jenkins - Installation

1. Download the war
   wget http://ftp-chi.osuosl.org/pub/jenkins/war/2.161/jenkins.war
2. Start it
   nohup java -Duser.home=/opt/jenkins/jenkins_home -Duser.timezone=America/Chicago -jar lib/jenkins.war --httpsPort=8080 &
3. Configure it
   http://localhost:8080
4. Blue Ocean & Create pipeline
   http://localhost:8080/blue
5. Create slaves/agents
   Dashboard > Manage Jenkins > Mange Nodes > ....
   The nodes:
1. can be any type of machine
2. can be manually activate/inactivate

Jenkins - Pipeline Syntax

The Jenkins Pipeline Syntax page (https://jenkins.io/doc/book/pipeline/syntax/)

Agent - specifies where the entire Pipeline, or a specific stage, will execute in the Jenkins environment depending on where the agent section is placed. It support docker and dockerfile in it.

Post - defines one or more additional steps that are run upon the completion of a Pipeline’s or stage’s run (depending on the location of the post section within the Pipeline). post can support any of of the following post-condition blocks: always, changed, fixed, regression, aborted, failure, success, unstable, unsuccessful, and cleanup

Stags - containing a sequence of one or more stage directives.

Steps - the steps section defines a series of one or more steps to be executed in a given stage directive.

Environment - specifies a sequence of key-value pairs which will be defined as environment variables for the all steps, or stage-specific steps, depending on where the environment directive is located within the Pipeline.

environment {
       SERVICE_CREDS = credentials('my-prefined-username-password')
}

Options/Parameters - 

Triggers - support cron, pollSCM and upstream 
When - Pipeline to determine whether the stage should be executed depending on the given condition.

Sequential/Parallel 

pipeline {
    agent any
    options {
        parallelsAlwaysFailFast()
    }
    stages {
        stage('Non-Parallel Stage') {
            steps {
                echo 'This stage will be executed first.'
            }
        }
        stage('Parallel Stage') {
            when {
                branch 'master'
            }
            parallel {
                stage('Branch A') {
                    agent {
                        label "for-branch-a"
                    }
                    steps {
                        echo "On Branch A"
                    }
                }
                stage('Branch B') {
                    agent {
                        label "for-branch-b"
                    }
                    steps {
                        echo "On Branch B"
                    }
                }
            }
        }
    }