jenkins-pipeline

Pipeline as code

Pipeline : Set of Jobs executed one after the other

We can write the code to create a Build pipeline and deployment pipeline

There are 2 types of syntax in which we can write the Jenkins pipeline code

1. Scripted pipeline syntax

 > when Jenkins version 1 was released
 > It is written in DSL - Domain specific language
 > really good and have knowledge on DSL on order to write the scripts
 > Is very complex
 > there is no proper structure of writing script
 > names of job, build steps, triggers, conditions
 > it become difficult for people to understand and execute them
 > It never validates the code for syntax error
 > it starts executing the script from the begining and any systax error occurs, the pipeline fails
 > after the fixing the issue, you have to execute the pipeline form the begining

node{

}
2. Declarative Pipeline syntax

 > with jenkins version 2 was released
 > This syntax is also based groovy script, which is declarative scripting in nature
for example: key value
 name 'sonal'
company 'edureka'
course 'devops'
tool 'Jenkins'

> This syntax provides a defined structure to your pipeline code
> we have to follow the strucure while writing the code
> because of which, reading and writing this syntax is easy
> Jenkins provides a tool --> Declarative pipeline snippet generator
> This tool is used to automatically generate pipeline code based on users input
> You can directly use the code in the pipeline.
> Before execution of the pipeline , jenkins will validate the code and give you syntax error
> Suppose a stage in the pipeline fails, you can fix the issue and restart the pipeline forma  particular stage


Structure of Declartive pipeline code:

pipeline {

// comments

tools{

OPTIONAL
provide information about which version of tools that will used to build the pipeline
you will write the code in declartaive format

    tool 'nameof the tool'

 tools configured as part of global tool configuration 

}


agent {

MANDATORY
           // list of VMs where you jobs have to be executed

right now for us, we will execute on the current jenkins machine
}

stages{

	stage('Job1')
	{
		triggers{
 				// give tirigger information
			}
		steps{
			mandatory
			// what should jenkins execute
			// conditions
       }
		post {
			success{
				// post build actions
       }
	}
}
	stage('Job2')
	{
		triggers{
 				// give tirigger information
			}
		steps{
			mandatory
			// what should jenkins execute
       }
		post {
			success{
				// post build actions
       }
	}
}
	stage('Job3')
	{
		triggers{
 				// give tirigger information
			}
		steps{
			mandatory
			// what should jenkins execute
       }
		post {
			success{
				// post build actions
       }
	}
}
	stage('Job4')
	{
		triggers{
 				// give tirigger information
			}
		steps{
			mandatory
			// what should jenkins execute
       }
		post {
			success{
				// post build actions
       }
	}
}


}



}



pipeline {
   agent any
   
   environment {
        NEWSTORES = "${sh(script:'cat /home/ait_l2/newstores_gcp', returnStdout: true)}"
    }

   stages {
      stage('init_env') {
         steps {
            echo "NEWSTORES = ${env.NEWSTORES}"
         }
      }
      stage('CM+_pin') {
         steps {
            build 'gcp_CM+_pin'
         }
      }
     stage('deploy_table_trigger') {
         steps {
            build 'deploy_table_triggers'
         }
      }
      stage('deploy_table_trigger_stream') {
         steps {
            build 'deploy_table_triggers_stream'
         }
      }
      stage('copy_magic_portal_files') {
         steps {
            build 'copy_mp_files'         
         }
      }
      stage('deploy_magic_portal') {
         steps {
            build 'deploy_mp_files'         
         }
      }
      stage('create_partition_on_apidb') {
          steps {
             sh label: '', script: "/usr/bin/ssh postgres@10.142.147.181 'sh /home/postgres/partition.sh ${env.NEWSTORES}'"




In jenkins we have a concept of JenkinsFile

With this jenkisn allows you to write pipeline code outside of Jenkisn server and maintain it in VCtool

Jenkins allows you to write pipeline code in file with name Jenkinsfile

The name of the file will be same and it has no extension

Inside this file you directly write the piplein code with stages, tools, environment information

you save and maintain this file in github repo

Team members can update the file --> commit history, version can be maintained

This file can be fetched by jenkins and execute the stages therby creating a pipeline in Jnekins server


**********************************
Multibranch Pipeline
*************************
I github repository in this repo we have various branch

Branch related to:

Dev ==> src ==> compile, review, build, deploy(dev)

QA   ==> compile, review, test, build, deploy(qa)

UAT ==> ompile, review, test, build, deploy(uat), UAT Testing

prod ==> the final build ==> deploy on production server


We have to create pipline for every branch
these pipelines should be created automatically in jenkins
the pipeline should have the name same as that of the branch
if the branch is deleted in github, automtically the pipeline job should also get deleted
the pipeline jobs have to be created only for dev, qa and uat and not for production
Pipeline code should be mainted in github -- Jenkisnfile