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βœ… What is a CI/CD Pipeline?

πŸ” CI/CD stands for:

  • CI = Continuous Integration
  • CD = Continuous Delivery or Continuous Deployment

A CI/CD pipeline automates the process of software delivery: from writing code, testing it, and building it β†’ to automated deployment into production environments.


🧱 Components of a CI/CD Pipeline:

Stage Description
Code Developer pushes code to a version control system (e.g., GitHub)
Build Code is compiled or packaged (e.g., into a Docker image)
Test Automated tests (unit, integration, etc.) run to catch bugs early
Release Artifacts or images are prepared for release
Deploy The application is automatically deployed to staging or production
Monitor Application health and performance are monitored

➑️ All this happens automatically, often triggered by a commit or pull request.


βš™οΈ What is Jenkins?

Jenkins is an open-source CI/CD automation server.

βœ… Key Features:

  • Runs build/test/deploy jobs automatically
  • Supports custom pipelines using Jenkinsfile (written in Groovy)
  • Thousands of plugins available
  • Works with Docker, Kubernetes, Git, and more

Example:

When you push code:

  1. Jenkins pulls the code
  2. Builds the project
  3. Runs tests
  4. Deploys to a server or Kubernetes
pipeline {
  agent any
  stages {
    stage('Build') {
      steps {
        sh 'npm install'
      }
    }
    stage('Test') {
      steps {
        sh 'npm test'
      }
    }
    stage('Deploy') {
      steps {
        sh './deploy.sh'
      }
    }
  }
}

πŸ› οΈ What is CircleCI?

CircleCI is a cloud-based CI/CD tool (hosted or self-managed) that automates testing, build, and deployment.

βœ… Key Features:

  • Quickly integrates with GitHub and GitLab
  • YAML-based configuration (.circleci/config.yml)
  • Fast performance with parallel jobs and caching
  • No server setup required (hosted by CircleCI)

Example Config:

version: 2.1
jobs:
  build:
    docker:
      - image: node:16
    steps:
      - checkout
      - run: npm install
      - run: npm test
      - run: ./deploy.sh

➑️ Best for teams wanting a quick and easy setup without maintaining infrastructure.


☸️ What is Argo CD?

Argo CD (Argo Continuous Delivery) is a GitOps-based CD tool for Kubernetes.

πŸ’‘ GitOps = "Git as the single source of truth"

Argo CD watches a Git repository and automatically:

  • Detects changes in Kubernetes manifests (YAML files, Helm charts, etc.)
  • Syncs those changes to your Kubernetes cluster
  • Allows automated or manual syncs
  • Provides a dashboard to manage deployments

Real-world Example:

  1. CircleCI builds your app and pushes a new Docker image to DockerHub
  2. It updates the image tag in a deployment.yaml file in Git
  3. Argo CD sees the change and automatically syncs it to the Kubernetes cluster

➑️ Argo CD is for deployment only, and it’s designed specifically for Kubernetes environments.


🧠 Summary Table

Tool Type Role in CI/CD Where It Works Best
CI/CD Pipeline Workflow/Process Automates build β†’ test β†’ deploy Across all DevOps and cloud environments
Jenkins CI/CD Tool Build, test, deploy (custom pipelines) On-premises, flexible automation needs
CircleCI CI/CD Tool Build, test, deploy (cloud-native) Fast, scalable CI for cloud/Git projects
Argo CD CD Tool βœ… (GitOps) Deploy only (Kubernetes apps) Kubernetes-focused CI/CD pipelines

πŸ”— How They Can Work Together:

  • Jenkins/CircleCI handles:

    • CI: Automated build, tests
    • CD: Builds and pushes Docker images β†’ updates Git repo with new manifest/tag
  • Argo CD handles:

    • CD: Watches Git for changes β†’ automatically deploys to Kubernetes

βœ… Real-World Flow Example:

[ Developer pushes code to GitHub ]
          ↓
[ CircleCI or Jenkins ]
   βœ“ Build project
   βœ“ Run tests
   βœ“ Build/push Docker image to registry
   βœ“ Update deployment YAML in Git repo
          ↓
[ Argo CD watches Git repo ]
   βœ“ Detects new change
   βœ“ Syncs change to Kubernetes cluster (auto-deploy)
    CI/CD Pipeline