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Rahul Joshi
Rahul Joshi

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Day 21 - CI/CD Fundamentals

#masterclassdevsecops #devops #webdev #developer

Modern software development moves incredibly fast.

A single application may receive:

  • Hundreds of commits daily
  • Multiple releases per week
  • Thousands of automated tests
  • Continuous security scans

Imagine manually building, testing, and deploying every code change.

It would look like:

Developer Writes Code
        ↓
Manual Build
        ↓
Manual Testing
        ↓
Manual Deployment
        ↓
Production Issues
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This approach doesn't scale.

This is why CI/CD became one of the most important practices in modern DevOps.

🔗 Resources

What is CI/CD?

CI/CD stands for:

Continuous Integration
Continuous Delivery / Continuous Deployment
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CI/CD is a software engineering practice that automates:

  • Building applications
  • Running tests
  • Security scanning
  • Packaging artifacts
  • Deploying applications

The goal is simple:

Deliver Software Faster
        +
Safer
        +
More Reliably
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Why CI/CD Matters

Before CI/CD, software releases often looked like:

Developers Work for Weeks
        ↓
Massive Release
        ↓
Unexpected Issues
        ↓
Rollback
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Common problems:

  • Human errors
  • Slow deployments
  • Integration conflicts
  • Unstable releases
  • Delayed feedback

CI/CD solves these challenges through automation.

The Evolution of Software Delivery 

Manual Deployments
        ↓
Build Automation
        ↓
Continuous Integration
        ↓
Continuous Delivery
        ↓
GitOps
        ↓
Platform Engineering
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Modern organizations rely heavily on CI/CD.

What is Continuous Integration (CI)?

Continuous Integration is the practice of frequently merging code into a shared repository.

Every code change triggers:

Git Commit
      ↓
Build
      ↓
Tests
      ↓
Security Scans
      ↓
Feedback
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Developers receive immediate feedback.

Why Continuous Integration?

Without CI:

Developer A
       ↓
Developer B
       ↓
Developer C
       ↓
Massive Merge Conflict
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With CI:

Small Changes
       ↓
Frequent Integration
       ↓
Early Problem Detection
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Benefits of Continuous Integration

Faster Feedback

Developers immediately know if code breaks.

Better Code Quality

Automated testing catches bugs earlier.

Fewer Integration Problems

Small changes are easier to merge.

Improved Team Collaboration

Everyone works from a shared codebase.

What is Continuous Delivery?

Continuous Delivery ensures applications are always ready for release.

Pipeline example:

Code Commit
       ↓
Build
       ↓
Test
       ↓
Security Scan
       ↓
Package
       ↓
Deploy to Staging
       ↓
Ready for Production
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A human approval step may still exist before production deployment.

What is Continuous Deployment?

Continuous Deployment goes one step further.

Code Commit
       ↓
Build
       ↓
Test
       ↓
Security Scan
       ↓
Production Deployment
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No manual approval required.

Every successful change reaches production automatically.

continues delivery

Modern CI/CD Architecture

Today's delivery pipelines look different from five years ago.

Traditional:

CI Tool
      ↓
Build
      ↓
Deploy
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Modern:

CI Pipeline
      ↓
Container Registry
      ↓
GitOps Repository
      ↓
ArgoCD / Flux
      ↓
Kubernetes
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GitOps has fundamentally changed CD.

Mostly CI Pipeline Stages

Modern CI pipelines usually contain:

Stage 1: Source Code 

Developer Commit
       ↓
GitHub / GitLab / Bitbucket
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Pipeline starts.

Stage 2: Secret Scanning

Detect:

  • API Keys
  • Tokens
  • Passwords

Popular tools:

  • Gitleaks
  • TruffleHog

Stage 3: Build

Compile application.

Examples:

mvn package
npm run build
dotnet build
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Stage 4: Unit Testing

Verify application logic.

Examples:

JUnit
PyTest
Jest
NUnit
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Stage 5: Static Security Testing

SAST Scans:

Source Code
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Popular tools:

  • SonarQube
  • Semgrep
  • Checkmarx

Stage 6: Software Composition Analysis

Checks dependencies.

Popular tools:

  • Snyk
  • Trivy
  • OWASP Dependency Check

Stage 7: Container Build 

Docker Build
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Creates application image.

Stage 8: Container Security Scan

Scan images for vulnerabilities.

Popular tools:

  • Trivy
  • Grype
  • Dockle

Stage 9: Push Artifact

Push:

Docker Hub
ECR
ACR
GCR
Harbor
Nexus
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Stage 10: Update GitOps Repository

Instead of deploying directly:

Update Manifest Repository
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Example:

image:
  tag: v1.5.0
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Commit changes.

Modern CD with GitOps

Today many organizations use:

CI Tool
      ↓
Build
      ↓
Push Image
      ↓
Update Git Repository
      ↓
GitOps Controller
      ↓
Deploy
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This separates CI from CD.

Why GitOps Became Popular

Traditional CD:

Pipeline Pushes Changes
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GitOps:

Cluster Pulls Changes
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Benefits:

  • Better security
  • Auditability
  • Rollback simplicity
  • Declarative deployments

Popular GitOps Tools

ArgoCD

One of the most popular GitOps platforms.

Features:

  • Kubernetes-native
  • Visual dashboard
  • Automatic synchronization
  • Rollbacks
  • Multi-cluster support

Architecture:

Git Repository
       ↓
ArgoCD
       ↓
Kubernetes Cluster
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FluxCD

Another GitOps platform.

Features:

  • Lightweight
  • Kubernetes-native
  • CNCF graduated project

Architecture:

Git Repository
       ↓
Flux Controller
       ↓
Kubernetes
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Popular CI/CD Platforms

Jenkins

The most popular traditional CI/CD platform.

Benefits:

  • Open source
  • Huge plugin ecosystem
  • Highly customizable

Best for:

Complex Enterprise Pipelines
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GitHub Actions

Native CI/CD for GitHub.

Example:

name: Build

on:
  push:

jobs:
  build:
    runs-on: ubuntu-latest
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Benefits:

  • Easy setup
  • GitHub integration
  • Marketplace actions

GitLab CI/CD

Built directly into GitLab.

Example:

stages:
  - build
  - test
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Benefits:

  • Integrated DevOps platform
  • Strong Kubernetes support

Azure DevOps

Microsoft's enterprise DevOps platform.

Features:

  • Pipelines
  • Boards
  • Repositories
  • Artifacts

Popular in enterprise environments.

Bitbucket Pipelines

Integrated with Bitbucket repositories.

Example:

pipelines:
  default:
    - step:
        script:
          - npm install
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CircleCI

Cloud-native CI/CD platform.

Popular among startups.

TeamCity

JetBrains CI/CD solution.

Common in enterprise Java environments.

Bamboo

Atlassian's CI/CD platform.

Used alongside:

  • Jira
  • Bitbucket
  • Confluence

popular cicd

CI/CD in Kubernetes Era

Modern Kubernetes pipelines often look like:

Developer Commit
       ↓
GitHub Actions / Jenkins
       ↓
Build Container
       ↓
Security Scans
       ↓
Push Image
       ↓
Update GitOps Repository
       ↓
ArgoCD / Flux
       ↓
Kubernetes Deployment
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This model has become the industry standard.

DevSecOps in CI/CD

Modern pipelines integrate security at every stage.

Example:

Commit
      ↓
Secret Scan
      ↓
SAST
      ↓
SCA
      ↓
Container Scan
      ↓
IaC Scan
      ↓
Deploy
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Security is no longer a separate phase.

CI/CD Best Practices

Keep Pipelines Fast

Developers should receive feedback quickly.

Automate Testing

Manual testing does not scale.

Integrate Security Early

Shift security left.

Use GitOps for CD

Prefer:

ArgoCD
FluxCD
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for Kubernetes deployments.

Version Everything

Store:

  • Source code
  • Infrastructure
  • Kubernetes manifests

inside Git.

Monitor Deployments

Deployment success is not enough.

Monitor:

  • Performance
  • Errors
  • Availability

Real-World Pre Prod Enterprise Pipeline

Demo Pipeline

Future of CI/CD

The industry is moving toward:

  • GitOps
  • Platform Engineering
  • AI-assisted pipelines
  • Policy as Code
  • Progressive Delivery
  • Automated Compliance
  • Zero-Touch Deployments

The future isn't just CI/CD.

It's:

Secure
Automated
GitOps-Driven
Cloud-Native Delivery
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Final Thoughts

CI/CD has transformed how software is delivered.

Instead of:

Manual Builds
Manual Tests
Manual Deployments
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we now have:

Automated Builds
Automated Testing
Automated Security
Automated Delivery
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Modern organizations typically use:

CI

  • Jenkins
  • GitHub Actions
  • GitLab CI
  • Azure DevOps
  • Bitbucket Pipelines

CD (GitOps)

  • ArgoCD
  • FluxCD

Together, these tools enable faster releases, higher quality software, stronger security, and reliable cloud-native deployments.

Whether you're a:

  • DevOps Engineer
  • Platform Engineer
  • Cloud Engineer
  • SRE
  • Software Developer

understanding CI/CD fundamentals is one of the most valuable skills in modern software engineering.

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