Definition

CI/CD and Jenkins Concepts with Definitions

Here’s a comprehensive list of CI/CD and Jenkins concepts, components, and definitions, along with explanations.

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🔹 CI/CD Concepts

1️⃣ Continuous Integration (CI)

🔹 CI is the practice of merging all developers’ code changes into a shared repository multiple times a day. ✅ Key Practices:

• Automated builds & tests

• Early bug detection

• Frequent code commits

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2️⃣ Continuous Delivery (CD)

🔹 Continuous Delivery ensures that every code change is automatically tested and prepared for deployment to production. ✅ Key Practices:

• Fully automated testing

• Need the Approval process before deployment

• Code is always in a deployable state

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3️⃣ Continuous Deployment

🔹 Continuous Deployment extends Continuous Delivery by automatically deploying changes to production without manual intervention. ✅ Key Practices:

• No manual approval needed

• Fully automated pipeline

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4️⃣ CI/CD Pipeline

🔹 A CI/CD Pipeline is an automated workflow that moves code from development to production through various stages like build, test, and deploy. ✅ Common Stages:

1. Source – Fetch code from a remote source like GitHub/GitLab/Bitbucket

2. Build – Compile and package the application

3. Test – Run automated unit and integration tests

4. Deploy – Deploy to staging or production

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5️⃣ Version Control System (VCS)

🔹 VCS is used to track and manage code changes. ✅ Examples: Git, GitHub, GitLab, Bitbucket

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6️⃣ Build Automation

🔹 The process of compiling source code into an executable format. ✅ Examples: Maven, Gradle, Ant

• Maven compiles Java source code into a .jar file

• npm run build for nextjs

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7️⃣ Artifact Repository

🔹 Stores build artifacts (executables, JARs, images). ✅ Examples: JFrog Artifactory, Nexus, AWS S3

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8️⃣ Infrastructure as Code (IaC)

🔹 Managing infrastructure using code instead of manual configuration. ✅ Examples: Terraform, Ansible, CloudFormation

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🔹 Jenkins Concepts & Components

1️⃣ Jenkins

🔹 Jenkins is an open-source automation server used to implement CI/CD pipelines.

✅ Why Jenkins?

• Automates builds, tests, and deployments

• Supports 1000+ plugins

• Can be integrated with Docker, Kubernetes, AWS, etc.

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2️⃣ Jenkins Architecture

🔹 Jenkins follows a master-agent architecture:

✅ Components:

1. Jenkins Controller (Master) – Manages jobs, scheduling, & user interface ui

2. Jenkins Agents (Slaves) – Executes jobs on different environments

3. Plugins – Extend Jenkins functionality

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3️⃣ Jenkins Job (Build Job)

🔹 A job is a unit of work in Jenkins, responsible for executing tasks (e.g., compiling code, running tests).

✅ Types of Jobs:

• Freestyle Project – Basic pipeline execution

• Pipeline Job – Uses Groovy scripts

• Multibranch Pipeline – For Git branches

• Parameterized Job – Accepts user inputs

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4️⃣ Jenkins Pipeline

🔹 A Jenkins Pipeline automates the software delivery process using Jenkinsfile (Groovy script).

✅ Pipeline Stages:

1. Build – Compile the application

2. Test – Run automated tests

3. Deploy – Deploy to staging or production

✅ Example:

pipeline {
    agent any
    stages {
        stage('Build') {
            steps {
                sh 'mvn clean package'
            }
        }
        stage('Test') {
            steps {
                sh 'mvn test'
            }
        }
        stage('Deploy') {
            steps {
                sh 'kubectl apply -f deployment.yaml'
            }
        }
    }
}

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5️⃣ Jenkinsfile

🔹 A Jenkinsfile is a text file that defines the Jenkins Pipeline using Declarative or Scripted syntax.

✅ Example (Declarative Pipeline):

pipeline {
    agent any
    stages {
        stage('Checkout') {
            steps {
                git 'https://github.com/myrepo.git'
            }
        }
        stage('Build') {
            steps {
                sh 'mvn package'
            }
        }
    }
}  
pipeline { stages { stage { steps { sh (command)

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6️⃣ Jenkins Plugins

🔹 Jenkins Plugins extend Jenkins functionalities (e.g., Git integration, Docker builds).

✅ Common Plugins:

• Git Plugin – Integrates GitHub/GitLab

• Pipeline Plugin – Enables Jenkinsfile

• Kubernetes Plugin – Runs Jenkins in Kubernetes

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7️⃣ Jenkins Webhooks

🔹 Webhooks trigger a Jenkins job when code is pushed to GitHub/GitLab.

✅ Example:

1. Configure GitHub Webhook

2. Set Jenkins to listen on port 8080

3. Trigger a job on a new commit

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8️⃣ Jenkins Declarative vs. Scripted Pipeline

🔹 Declarative Pipeline (Easier, recommended) ✅ Example:

pipeline {
    agent any
    stages {
        stage('Test') {
            steps {
                sh 'pytest'
            }
        }
    }
}

🔹 Scripted Pipeline (More flexible) ✅ Example:

node {
    stage('Test') {
        sh 'pytest'
    }
}

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9️⃣ Jenkins Distributed Builds

🔹 Jenkins Agents (Slaves) execute jobs on different machines for parallel processing.

✅ Why Use Agents?

• Distribute workload

• Run builds on specific OS (Linux, Windows)

• Optimize CPU/memory usage

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🔟 Jenkins Credentials Management

🔹 Used for securely storing API keys, passwords, SSH keys.

✅ Example Using Credentials in Pipeline:

withCredentials([usernamePassword(credentialsId: 'aws-cred', usernameVariable: 'AWS_USER', passwordVariable: 'AWS_SECRET')]) {
    sh 'aws s3 ls'
}

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1️⃣1️⃣ Jenkins Blue Ocean

🔹 A modern UI for Jenkins to visualize pipelines easily.

✅ Why Use It?

• Drag-and-drop pipeline editor

• Better visualization of stages

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1️⃣2️⃣ Jenkins Shared Libraries

🔹 Used to reuse common pipeline logic across multiple projects.

✅ Example:

@Library('my-shared-library') _
pipeline {
    agent any
    stages {
        stage('Deploy') {
            steps {
                deployApp()
            }
        }
    }
}

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1️⃣3️⃣ Jenkins Backup & Restore

🔹 Backup Jenkins Data

cp -r /var/lib/jenkins /backup/

🔹 Restore Jenkins

cp -r /backup/jenkins /var/lib/

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1️⃣4️⃣ Jenkins Security Best Practices

✅ Follow These:

• Enable authentication

• Restrict access to jobs

• Use role-based access control (RBAC)

• Store secrets securely

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1️⃣5️⃣ Jenkins vs. Other CI/CD Tools

Feature	Jenkins	GitHub Actions	GitLab CI	CircleCI
Open Source	✅	✅	✅	❌
Plugins	✅ 1000+	❌ Limited	✅	❌
Self-Hosted	✅	✅	✅	❌

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🚀 Conclusion

This comprehensive list covers all major CI/CD & Jenkins concepts with definitions. Let me know if you need specific examples, troubleshooting, or advanced topics! 🚀