DevOps - Jenkins

Software Development evolution

• Water fall
• Requirements are clear and fixed
• Product definition is stable
• Agile
• Requirements change frequently
• Development needs to be fast
  
• Devops
• Requirements change frequently
• Development needs to be fast 
• Operations need to be agile/fast 

DevOps is a Software development Approach 

• Continuous Development
• Planning & Coding
  
• Continuous Testing
•  
• Continuous Integration
• Jenkins
• Process of automated build & Tests
• 
  
• Continuous Deployment
• Keeping application deployable at any point of time 
• Configuration management(server configuration)
  
• Containerazation
  
• Continous Delivery
• Practice of keeping code base deployable at any point of time. It is beyond making sure automated tests pass to have all configurations necessary to push to production.
  
• Continuous Monitoring

Jenkins

•  Continuous Integration
• It is a development practice that requires developers to integrate code into a shared repository several times a day
• Each checkin is verified by automated build which helps to detect problems early
• Process
• Developers checkout code in their workspace
• Commit the new changes to repository
• CI server monitors the repository and checks out changes when they occur
• CI server builds the system and runs unit & integration tests
• CI server releases deployable artifacts for testing
• CI server assigns a build label to the version of code it just built
• Jenkins
• CI/CD tool written in java
• Used to build & deliver 
• Forked from another product HUDSON
• It is server based application that requires server like tomcat
• why it popular
• Monitoring of repeated tasks which arise in development of a project
• 
  

• Installation 
• docker run -p 7979:8080 -p 50000:50000 -v ~/jenkins_home:/var/jenkins_home jenkins/jenkins:lts
• admin/wcalto  or vdesu/wcalto
• Container

• docker exec -it -u root jenkins /bin/bash

   

Jenkins terminoloty

• Jenkins Job
• Any runnable tasks that are controlled and monitored by Jenkins
• Slave/Node
• VMs that are setup to build projects for a master
• Jenkins Slave
• Jenkins run separate program called "Slave Agents" on Slaves
• Slaves are connected to master 
• Node
• All machines that are part of Jenkins grid, slaves & master
• Executor
• Separate stream of builds to be run on a Node in parallel
• Plugins
• Piece of software that extends core functionality of the core Jenkins Server
• 
  

Docker

    https://www.youtube.com/watch?v=7KCS70sCoK0&list=PLy7NrYWoggjw_LIiDK1LXdNN82uYuuuiC&index=6

•  docker run -d -v jenkins_home:/var/jenkins_home -p 7575:8080 -p 50000:50000 jenkins/jenkins:lts

• 7575 for external visibility
• 50000 is master/slave communication
• -d for detached mode
• -v -> named volume
• docker logs <container id>
• copy pwd from logs to eda5e9224b9c451d8e1e6ee22fdc873f  localhost:7575
• install standard plugins

Types of Projects

• Freestyle
• simple & single test
  
• Pipeline
• Whole delivery flow eg: test, build...
  
• Multibranch Pipeline
• For multiple branches
•  

Maven Freestyle project: https://www.youtube.com/watch?v=kO7wrtY2b3E

Jenkins Pipeline- https://www.youtube.com/watch?v=pzbrVVy6ul4

• Jenkins pipeline means Pipeline as a code
• we have 2 types of jenkins pipeline
• Scripted
• needs groovy script knowledge
  
• Declarative
• simple way
  

 

Jenkinsfile-> Pipeline as a code ie scripted pipeline

https://www.youtube.com/watch?v=pzbrVVy6ul4&list=RDCMUC_evcfxhjjui5hChhLE08tQ&start_radio=1&t=0

• scripted 
• first syntax
• groovy engine
• adv scripting capabilities
• difficult to start 
• node{
      stage(‘sim checkout’){
          git ‘<url>’
      }
      stage(‘compile pkg’){
          def mvnHome = tool name: ‘maven-3’,type: ‘maven’
          sh “${mvnHome}/bin/mvn package”
  }
  }
  
• declarative
• recent edition
• easy to start but not powerful
  
•  predefined structure
• pipeline {
    agent any
      stages {
        stage("build") {
          steps {
          }
        }
      }
    }
• agent - where to execute 
• stages - where the whole work happens
• steps - build, test, deploy
•