Jenkins: Comprehensive Guide

Introduction

• Overview of Jenkins and its significance in DevOps
• Engineers' salary range: $150,000 to $250,000 per year
• Jenkins is used for automation of various tasks including code pipelines

Jenkins Basics

• Jenkins is an automation platform for build, test, and deploy software using pipelines
• It offers a web GUI for creating jobs and managing functionalities like source control, build actions, and triggers

Jenkins Infrastructure

• Master Server: Controls the pipelines, schedules builds to agents
• Agents: Run the build in their workspace
• Workflow: Developer commits code -> Jenkins triggers pipeline -> Build distributed to agents
• Types of Agents: Permanent and Cloud Agents
  • Permanent Agents: Standalone servers (Linux/Windows) with Java and SSH configured
  • Cloud Agents: Dynamic agents from Docker, Kubernetes, AWS, etc.

Setting Up Jenkins

• Two main options: install directly on OS or use container environments like Docker/Kubernetes
• Recommended to use Docker
• Key setup steps: Build Docker image, create network, launch container, unlock Jenkins, install plugins

Jenkins UI Overview

• Main Features: Dashboard, Manage Jenkins, New Item, etc.
• Breadcrumbs: Easy navigation
• Manage Tools: Plugins, Nodes, Credentials, Security settings
• Job Creation: Freestyle Projects and Pipelines
  • Freestyle: Simple, UI-driven, suitable for beginners
  • Pipelines: Uses Jenkinsfiles with Groovy syntax, suitable for complex automated workflows

Creating Jenkins Jobs

• Freestyle Projects: Use UI and plugins to define steps
  • Example: Echo “Hello World”, setup build environment, execute shell script
• Pipeline Jobs: Define steps in Jenkinsfile
  • Example Pipeline Stages: Clone, Build, Test, Deploy

Advanced Jenkins Setup

• Agents Configuration:
  • Permanent Node Agents
  • Cloud Agents using Docker
    • Ensure Docker setup on local/remote
    • Create and configure Docker agent templates
• Build Triggers: Automatic builds using webhooks or SCM polling

Jenkinsfile and Pipelines

• Defining Pipelines in Jenkinsfile:
  • Use Groovy syntax, declarative recommended for beginners
  • Define stages, agents, and steps

Example Jenkinsfile Contents:

pipeline {
  agent { label 'docker-agent-python' }
  stages {
    stage('Build') {
      steps {
        echo 'Building...'
        sh 'cd my_app && pip install -r requirements.txt'
      }
    }
    stage('Test') {
      steps {
        echo 'Testing...'
        sh 'cd my_app && python3 hello.py'
      }
    }
    stage('Deploy') {
      steps {
        echo 'Deploying...'
      }
    }
  }
}

• Pipeline Workflow:
  • Stages for building, testing, and deploying
  • Example involved running a Python script, and checking its output

Blue Ocean Plugin

• Enhances CI/CD pipeline visualization
• Easy navigation and troubleshooting of pipelines

Conclusion

• Core skills covered: Setting up Jenkins, configuring agents, creating jobs, and writing Jenkins pipelines
• Encouragement to explore further content and practical applications of Jenkins