Getting Started with Jenkins 🔧

Introduction to Jenkins

• Comprehensive guide including both theory and practical labs.
• Jenkins is a sought-after DevOps skill, and engineers can earn between $150,000 to $250,000 per year.
• Jenkins is an automation platform that can build, test, and deploy software using pipelines.
• Can automate a variety of tasks, including running Bash, Python scripts, and Ansible playbooks.
• Provides a web GUI to create jobs and manage functionalities (source control, build actions, triggers).

Jenkins Infrastructure

• Master Server: Controls pipelines and schedules builds to agents.
• Agents: Execute jobs in their workspace.
• Workflow example: Commit to a Git repo → Jenkins master triggers pipeline → Build distributed to an agent.
• Types of Jenkins agents:
  • Permanent Node Agents: Standalone Linux/Windows servers configured to run Jenkins jobs.
    • Need Java installed and SSH configured.
  • Cloud Agents: Dynamically spun up (e.g., Docker, Kubernetes, AWS Fleet Manager).
    • Configured via agent templates (demonstrated with Docker in the lab).

Types of Jenkins Build Jobs

• Freestyle Build Projects:
  • Simplest way to get started, like running shell scripts.
  • Easily managed through the GUI and plugins.
  • Executed by shell scripts; familiar with shell scripting or Linux command line is beneficial.
• Pipelines:
  • Use Jenkins files written in Groovy syntax.
  • Common stages: Clone, Build, Test, Package, Deploy.
  • Jenkins files provide a way to specify what happens during the build in a structured manner.

Setting Up Jenkins

• Installation options on the website: Direct installation on the OS, Docker, or Kubernetes.
• Suggested method: Use Docker.
• Summary of steps from the GitHub repository:
  1. Build the Docker image.
  2. Create a Docker network called jenkins.
  3. Launch the Docker container.
• Detailed setup instructions and commands are provided in the repository (e.g., Dockerfile setup, commands to build and run Jenkins).

Jenkins Interface Overview

• Main items in Jenkins UI:
  • Breadcrumbs: Navigation aid.
  • New Item: Create projects and pipelines.
  • People: Manage user accounts.
  • Build History: History of all jobs run.
  • Manage Jenkins: Main management section (agents setup, plugins, etc.).
  • My Views/New View: Organize jobs and their display.
  • Blue Ocean: Enhances CI/CD pipelines' UI.
• Manage Jenkins sub-sections of interest:
  • Configure System: Global parameters for the Jenkins server.
  • Manage Plugins: Install and manage plugins.
  • Manage Nodes and Clouds: Setup agents and cloud services.
  • Security: Manage users and credentials.

Setting Up Jenkins Agents

• Permanent Agents: Suitable for older setups, configured via SSH.
• Cloud Agents: More modern approach using platforms like Docker, Kubernetes, AWS.
  • Example setup with Docker:
    • Install Docker plugins from Jenkins plugin manager.
    • Set Docker Cloud Details.
    • Create Docker Agent Templates specifying Docker images and other configurations.
    • Test with labels and verify builds.

Creating Jenkins Build Jobs

• Freestyle Projects:
  • Easy to set up; use UI and plugins.
  • Basic workflows using shell scripts (example: `echo