β What is a CI/CD Pipeline?
π 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.
π§± 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 |
β‘οΈ All this happens automatically, often triggered by a commit or pull request.
βοΈ What is Jenkins?
Jenkins is an open-source CI/CD automation server.
β 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:
- Jenkins pulls the code
- Builds the project
- Runs tests
- 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'
}
}
}
}
π οΈ What is CircleCI?
CircleCI is a cloud-based CI/CD tool (hosted or self-managed) that automates testing, build, and deployment.
β 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
β‘οΈ Best for teams wanting a quick and easy setup without maintaining infrastructure.
βΈοΈ What is Argo CD?
Argo CD (Argo Continuous Delivery) is a GitOps-based CD tool for Kubernetes.
π‘ 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:
- CircleCI builds your app and pushes a new Docker image to DockerHub
- It updates the image tag in a
deployment.yaml
file in Git - Argo CD sees the change and automatically syncs it to the Kubernetes cluster
β‘οΈ Argo CD is for deployment only, and itβs designed specifically for Kubernetes environments.
π§ 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 β (GitOps) | Deploy only (Kubernetes apps) | Kubernetes-focused CI/CD pipelines |
π 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
β Real-World Flow Example:
[ Developer pushes code to GitHub ]
β
[ CircleCI or Jenkins ]
β Build project
β Run tests
β Build/push Docker image to registry
β Update deployment YAML in Git repo
β
[ Argo CD watches Git repo ]
β Detects new change
β Syncs change to Kubernetes cluster (auto-deploy)