DevOps Classroom Series – 28/Nov/2021

Continuous Integration/Delivery/Deployment using CI/CD Engines

• Importance of Day builds and Night Builds
• During the build process
  • Get the current latest version from git
  • Build/Package the code
    • This is technology specific
      • Java => ANT, MAVEN, GRADLE
      • Dotnet => msbuild
      • nodejs => Gulp
      • python
      • ruby
    • Possible outcomes:
      • Build Successful
      • Build failed
  • Run the unit-tests => Technology specific
    • Possible outcomes:
      • Unit tests passed
      • Unit tests failed
  • Static Code Analysis => Many options
    • Possible outcomes:
      • We might get corrections that can be made
      • All the code is good
• Hint: As a DevOPs Engineer the minimum knowledge which you need to have is
  • How to execute build/packaging the code (from command line)
  • How to run unit tests (from command line)
  • How to perform static code analysis

Jenkins

• History:

• Versions:

  • 1.x
  • 2.x

• Install Jenkins:

  • Overview
  • Lab Setup: Create an ubuntu 20.04 VM (free tier eligible)
  • Installation Steps : Refer Here
    • Install java 11

    sudo apt update
    sudo apt-cache search openjdk #to find the java packages
    sudo apt install openjdk-11-jdk -y
    java -version
    

    • Install jenkins LTS

    curl -fsSL https://pkg.jenkins.io/debian-stable/jenkins.io.key | sudo tee \
    /usr/share/keyrings/jenkins-keyring.asc > /dev/null
    echo deb [signed-by=/usr/share/keyrings/jenkins-keyring.asc] \
    https://pkg.jenkins.io/debian-stable binary/ | sudo tee \
    /etc/apt/sources.list.d/jenkins.list > /dev/null
    sudo apt-get update
    sudo apt-get install jenkins
    

    • To install a specific version of jenkins Refer Here
    • After installing jenkins on a linux machine a user called as jenkins is created
      • The home directory of this user is /var/lib/jenkins
    • Configuring Jenkins:
      • Navigate to http://publicip:8080

• Installation steps for centos/redhat

sudo yum search openjdk
sudo yum install java-11-openjdk-devel -y
sudo wget -O /etc/yum.repos.d/jenkins.repo   https://pkg.jenkins.io/redhat-stable/jenkins.repo --no-check-certificate
sudo rpm --import https://pkg.jenkins.io/redhat-stable/jenkins.io.key
sudo yum upgrade
sudo yum install epel-release -y
sudo yum install jenkins -y
sudo systemctl daemon-reload
sudo systemctl status jenkins.service
sudo systemctl enable jenkins.service
sudo systemctl start jenkins.service

• If i want to run some commands periodically on a server or laptop,
  • Windows => Scheduler
  • Linux => Cron Job
• Jenkins is a Cron/Scheduler on Steriods fine tuned for Continuous Integration and Continuous Deployment

Jenkins Core concepts

• In Jenkins to create a pipeline we would create a jenkins Job/Project

• Create a New project

• In the job/project which we have configure the commands which we specified are

  • whoami => This will tell as which user is jenkins running the commands on the server
  • pwd => from which directory is jenkins working

• Lets see build results

• From these results we can claim when we execute jenkins job, the commands are executed as jenkins user and the current working directory is /var/lib/jenkins/workspace/hellojenkins

• What this means is running from jenkins is

  • login into the server as jenkins user and execute the commands
  • SO we can simulate the same

• Now lets add some more steps to build

• Now to simulate this failure try to login into linux system as jenkins user and then check the output

• here the command is asking for password, so jenkins has failed the job

• Plugin is an addon to jenkins, which provides functionality on the jenkins ui

  • Installing plugin is not equal to installing software on the jenkins server
  • Now in this server git plugin is installed