Introduction to Jenkins and CI/CD for Beginners

Continuous Integration (CI) and Continuous Delivery/Deployment (CD) are essential practices in modern DevOps. They help teams automate software testing, building, and delivery to make the process faster and more reliable. Jenkins, an open-source automation tool, is one of the most popular choices for creating these CI/CD pipelines.

Whether you’re new to DevOps, a developer moving into this field, or an IT professional updating software delivery methods, understanding the basics of Jenkins is very important. This guide will explain what Jenkins is, how it works, its key features, and how it compares with other tools. It’s written so beginners can easily follow and build a strong foundation in Jenkins and CI/CD.

What is Jenkins?

Jenkins is an open-source automation server. It automates tasks like building, testing, and deploying software. Think of Jenkins as a smart conductor that coordinates all the steps in your software development process, making sure everything happens smoothly and automatically.

• Type: Automation Server
• Main Use: CI/CD (Continuous Integration and Delivery)
• Strength: Huge plugin library with over 1800 plugins

Imagine your software project as a car assembly line. Jenkins manages each step—building parts, testing, and finishing—so everything happens in the right order without human intervention.

Why Jenkins is Important in DevOps

In DevOps, Jenkins helps by:

• Automating repetitive tasks such as running builds and tests
• Providing quick feedback to developers after code changes
• Encouraging teamwork with standard pipelines
• Scaling to support projects from small to very large and complex

Simply put, CI/CD drives DevOps success, and Jenkins is a popular tool to start this engine.

Basic Jenkins Concepts Every Beginner Should Know

pipeline {
    agent any
    stages {
        stage('Build') {
            steps {
                sh 'mvn compile'
            }
        }
        stage('Test') {
            steps {
                sh 'mvn test'
            }
        }
        stage('Deploy') {
            steps {
                sh 'mvn deploy'
            }
        }
    }
}
                        

1. Job (Project)
   A Jenkins job is an automated task you set up, like pulling code from Git, building the software, running tests, and packaging the result. Beginners often start with simple “Freestyle Jobs” before moving to “Pipeline Jobs” using Jenkinsfiles, which enable writing automation code.
2. Master-Agent Setup
   Jenkins uses two roles:

• Controller (Master): Schedules and manages jobs
• Agent (Worker): Runs the actual build or test tasks
  This design lets Jenkins spread work across several machines, speeding up processes.

3. Pipelines
   Pipelines are the heart of Jenkins automation. They are sets of instructions written in a special format (Groovy) inside a file called Jenkinsfile. A pipeline might include steps like: getting code, running tests, building software packages, deploying to environments, and sending notifications.
4. Plugins
   Jenkins is highly flexible due to its plugins, which add features and connect Jenkins to other tools like GitHub, Docker, Kubernetes, and Slack. Examples include the Git plugin for source control and the Docker plugin for container tasks.
5. Jenkinsfile
   This file defines the CI/CD pipeline using code. There are two types:

• Declarative Pipeline: Easier for beginners with clear syntax
• Scripted Pipeline: More powerful but needs advanced skills

Getting Started: Installing Jenkins

Try Jenkins right away with these easy options:

• Using Docker (fast and simple):
  Run Jenkins in a container with commands like:

bashdocker run -p 8080:8080 -p 50000:50000 jenkins/jenkins:lts  

Then visit http://localhost:8080 to open Jenkins.

• Using Native Package (for Ubuntu/Debian):
  Install Java, add Jenkins repository keys, and install Jenkins with apt commands. This method takes a few steps but works well for local or server installations.

Example: A Simple Jenkins CI/CD Pipeline

Here’s how a basic automated pipeline works:

• Developer pushes code to GitHub
• Jenkins notices the change and triggers a job
• It compiles the code and installs dependencies
• Runs unit and integration tests
• If tests pass, builds a Docker image
• Deploys the image to a test or staging environment
• Notifies the team via Slack or email about success or failure

This automation ensures every change gets tested and deployed consistently.

Jenkins Strengths and Weaknesses

Alternatives to Jenkins

As Jenkins isn’t the only option, here are alternatives depending on your setup:

• GitHub Actions: Best for GitHub users, easy YAML pipelines
• GitLab CI/CD: Great integration for GitLab repos and containers
• CircleCI: Cloud-native, good for fast scaling
• Tekton: Kubernetes-native, great for cloud-focused teams
• Azure DevOps/AWS CodePipeline: Ideal for enterprises in Microsoft or AWS ecosystems

Tips for Getting Started with Jenkins

• Begin with small, simple jobs
• Use Jenkinsfile (Pipeline as Code) for easier maintenance
• Secure Jenkins with proper user management
• Monitor your Jenkins instance using plugins and dashboards
• Consider running Jenkins in Docker or Kubernetes for easier scaling

The Future of Jenkins

Jenkins remains a key tool in DevOps, especially in large organizations using its plugin ecosystem. However, learning modern cloud-native alternatives alongside Jenkins will broaden your skills and options.

Conclusion

Jenkins is a stepping stone into the world of DevOps automation. Learning its basics helps you understand core CI/CD concepts, pipeline automation, and tool integration. Whether you continue with Jenkins or explore newer tools, these skills form the foundation of efficient software delivery.

Devraj Sarkar

Cybersecurity Architect | Cloud-Native Defense | AI/ML Security | DevSecOps

With over 23 years of experience in cybersecurity, I specialize in building resilient, zero-trust digital ecosystems across multi-cloud (AWS, Azure, GCP) and Kubernetes (EKS, AKS, GKE) environments. My journey began in network security—firewalls, IDS/IPS—and expanded into Linux/Windows hardening, IAM, and DevSecOps automation using Terraform, GitLab CI/CD, and policy-as-code tools like OPA and Checkov.

Today, my focus is on securing AI/ML adoption through MLSecOps, protecting models from adversarial attacks with tools like Robust Intelligence and Microsoft Counterfit. I integrate AISecOps for threat detection (Darktrace, Microsoft Security Copilot) and automate incident response with forensics-driven workflows (Elastic SIEM, TheHive).

Whether it’s hardening cloud-native stacks, embedding security into CI/CD pipelines, or safeguarding AI systems, I bridge the gap between security and innovation—ensuring defense scales with speed.

Let’s connect and discuss the future of secure, intelligent infrastructure.