Understanding CI, CD, and CT in DevOps

CI, CD, and CT are essential practices in DevOps that streamline the software development lifecycle.

Continuous Integration (CI) automates code integration, Continuous Testing (CT) ensures quality through automated tests, and Continuous Deployment (CD) automates the release process. Together, they enable faster, more reliable software delivery with minimal manual intervention.

This article will explore these practices, their integration in DevOps pipelines, their key differences, and the challenges and benefits they bring to modern development workflows.

What is CI in DevOps?

Continuous Integration (CI) is a DevOps practice where developers frequently commit code changes to a shared repository, often multiple times daily. Each commit triggers an automated build and testing process to ensure the code integrates seamlessly into the existing codebase.

Key Features of CI

Automated builds and tests for every code commit
Early bug detection and quick remediation
Frequent commits to a shared branch are needed to avoid integration issues

Popular CI Tools: Jenkins, GitHub Actions, GitLab CI, CircleCI.

What is CD in DevOps?

Continuous Deployment (CD) is the automated process of delivering code changes to production once they pass all required tests. It eliminates manual intervention and ensures the applications are ready for release. Continuous Deployment also enables constant feedback and iteration, allowing teams to adapt to changing user needs efficiently.

CD often refers to both Continuous Delivery and Continuous Deployment, but they are different. Continuous Delivery requires manual approval before deployment, while Continuous Deployment automates deployment directly to production.

Key Features of Continuous Deployment

Automated delivery pipelines
Frequent and reliable releases
Improved scalability and faster user feedback

Popular Tools for CD: Azure DevOps, GoCD, Harness, Bamboo, and AgroCD.

What is CT in DevOps?

Continuous Testing (CT) is a software development practice that regularly runs automated tests to ensure the software functions as expected. It works alongside Continuous Integration (CI) and Continuous Deployment (CD), where code changes are frequently merged into a shared repository, automatically built, tested, and deployed to production.

Key Features of CT

Automated execution of unit testing, integration testing, and end-to-end testing
Comprehensive test coverage
Early detection of performance and security issues

Key Differences Between CI, CD, and CT

Below is a table highlighting the key differences between CI, CD, and CT.

Aspect	CI	CT	CD
Purpose	Integrates code changes into a shared repository frequently	Ensures software quality through automated testing at all stages	Automates the deployment of code changes to production
Focus	Code integration and build processes	Validating functionality, performance, and security	Delivery and deployment of production-ready code
Automation	Automates builds and initial tests for every commit	Automates unit, integration, end-to-end, and other types of tests	Automates the deployment pipeline after successful testing
Outcome	Detects integration issues early	Identifies bugs, performance issues, and security vulnerabilities	Ensures frequent and reliable releases
Environment	Works mainly in development and staging environments	Works across all environments, from development to production	Directly affects production environments by deploying live updates
Primary Goal	Ensure new code works well with the existing codebase	Ensure code quality through rigorous testing throughout the pipeline	Automatically release code to production without manual intervention
Impact on teams	Encourages collaboration by ensuring all developers integrate code regularly	Improves team confidence by catching issues early and ensuring quality	Reduces deployment-related stress and ensures faster time to market
Tools	Jenkins, GitHub Actions, GitLab CI, CircleCI	Selenium, Cypress, Playwright, BrowserStack	Azure DevOps, Spinnaker, Harness, ArgoCD

Integrating CI, CD, and CT in the DevOps Pipeline

In a DevOps pipeline, Continuous Integration (CI), Continuous Deployment (CD), and Continuous Testing (CT) work together to streamline the software development lifecycle, ensure software quality, and efficiently deliver changes to production.

How Does It Work?

Continuous Integration (CI): Developers frequently commit code changes to a shared repository. Each commit triggers an automated build and testing process to ensure the new code integrates well with the existing codebase.
Continuous Testing (CT): Automated tests are run at every pipeline stage—unit, integration, and end-to-end tests. This validates code quality, detects issues early, and reduces risks.
Continuous Deployment (CD): As the final stage in the DevOps pipeline, code changes are deployed automatically to production or staging environments after passing all tests. This ensures rapid, reliable releases and enables continuous feedback for further improvements.

Here’s how it works.

1. Continuous Integration (CI) Example

This example demonstrates how to automate checking out code, installing dependencies, and running unit tests using GitHub Actions.

Using GitHub Actions for CI:

# .github/workflows/ci.yml



name: CI Pipeline



on:

  push:

    branches:

      - main



jobs:

  build-and-test:

    runs-on: ubuntu-latest



    steps:

      - name: Checkout Code

        uses: actions/checkout@v3



      - name: Install Dependencies

        run: npm install



      - name: Run Unit Tests

        run: npm test

Output:

When a developer pushes code to the main branch, GitHub Actions will:

Check the repository.
Install project dependencies.
Run unit tests to validate the code.

Follow-Up Read: How to run test on GitLab CI Locally

2. Continuous Testing (CT) Example

This example shows how to use Cypress to automate end-to-end testing for a login page, verify functionality, and generate a test report.

Using Cypress for end-to-end testing:

cypress.json (configuration file):



{

  "baseUrl": "http://localhost:3000",

  "integrationFolder": "cypress/integration"

}

Example Test: cypress/integration/login.spec.js

describe('Login Page', () => {

  it('should log in with valid credentials', () => {

    cy.visit('/login');

    cy.get('input[name="username"]').type('testuser');

    cy.get('input[name="password"]').type('password123');

    cy.get('button[type="submit"]').click();

    cy.url().should('include', '/dashboard');

  });

});

Command to Run Tests on bash:

npx cypress run

Output:

Cypress will execute the test, verify login functionality, and generate a test report.

3. Continuous Deployment (CD) Example

This example illustrates how to use GitLab CI/CD to build the application, run tests, and deploy it to a Kubernetes cluster automatically.

Using GitLab CI/CD to deploy to a Kubernetes cluster using YAML:

stages:

  - build

  - test

  - deploy



build:

  stage: build

  script:

    - echo "Building the application..."

    - npm install

    - npm run build

  artifacts:

    paths:

      - build/



test:

  stage: test

  script:

    - echo "Running tests..."

    - npm test



deploy:

  stage: deploy

  script:

    - echo "Deploying to Kubernetes..."

    - kubectl apply -f k8s-deployment.yaml

    - kubectl rollout status deployment/my-app

  environment:

    name: production

    url: http://my-app.com

Output:

The pipeline builds the application, runs tests, and deploys it to a Kubernetes cluster.
Once deployed, the application is accessible at the specified URL.

Benefits of CI/CD/CT Pipelines

The following are the benefits of CI/CD/CT pipelines.

Faster software delivery: Automating building, testing, and deployment helps developers release updates quickly
Improved software quality: Automated testing ensures code meets quality standards and reduces defects before deployment
Minimized risk of errors: Automation removes human errors from manual deployments and improves release reliability

Increased efficiency: Automating repetitive tasks like building and testing allows developers to focus on critical work
Stronger security: Automated testing and deployment of security patches help protect applications from vulnerabilities
Better team collaboration: Streamlined code merging, automated testing, and faster deployments help teams work more efficiently

Challenges in Implementing CI/CD/CT

The key challenges in implementing CI, CD, and CT pipelines include,

Complex setup and configuration: Setting up a CI/CD/CT pipeline can be intricate, particularly for large teams or legacy systems. Configuring the right tools, workflows, and integrations often requires specialized knowledge and can be time-consuming.
Choosing the right tools: With a wide variety of CI/CD/CT tools available, selecting the right combination for your project can be overwhelming. The wrong choice or lack of expertise in these tools can lead to inefficiencies and frustration.
Integration with existing systems: Integrating CI/CD/CT practices into existing workflows can be challenging for teams working with legacy applications or older infrastructure. This requires rethinking processes and possibly modifying systems not designed for automation.
Security risks: Automating deployment and testing processes can introduce many risks, especially if sensitive data or production environments are not adequately secured. Failing to manage the security aspects of automation can expose vulnerabilities.
Ongoing monitoring and maintenance: CI/CD/CT pipelines require regular monitoring and maintenance to remain effective. Issues such as failing tests, slow builds, or misconfigured deployment processes can create bottlenecks that may need constant attention.
Cultural resistance: Teams accustomed to traditional manual processes may resist adopting CI/CD/CT practices. Transitioning to automated workflows requires careful change management and support to ensure smooth adoption and alignment across the team.

Talk to an Expert

Why Choose BrowserStack for Testing?

BrowserStack provides instant access to real devices and browsers on the cloud. It integrates with popular CI/CD tools like TeamCity, Circle CI, Travis CI, Jenkins, and GitHub Actions to ensure automated tests run on every commit. Furthermore, its automated parallel test execution speeds up testing across multiple devices.

BrowserStack Automate offers powerful features for efficient and reliable testing, including

Real Devices and Browsers: Test on over 3500+ real mobile devices and desktop browsers via BrowserStack’s Cloud Selenium Grid. This allows you to test your app work across various real environments.
Day 0 Access to New Devices: Test on the latest devices as soon as they are released. This ensures your CI/CD pipeline stays ahead with compatibility for new technologies from day one.
Parallel Test Runs: Run multiple tests in parallel to reduce test execution time by 10x, which will help you get faster feedback and accelerate your continuous testing process.
Seamless CI/CD Integration: Easily integrate BrowserStack with your CI/CD pipeline using plugins for Jenkins, GitHub, and other tools to automate your testing workflows without friction.
Comprehensive Debugging: Enhance your continuous testing with features such as video recordings, screenshots, logs, network traces, etc., to quickly identify and resolve issues.
Zero Setup and Maintenance: BrowserStack’s plug-and-play solution eliminates complex setup and maintenance. This allows your team to focus on automating tests and improving code quality.

Conclusion

CI, CD, and CT are key elements of modern DevOps pipelines, helping teams deliver software faster, more reliably, and with better quality. They simplify the development process by automating integration, testing, and deployment. While there are challenges, tools like BrowserStack make it easier to implement these practices and give organizations a competitive edge.

Try BrowserStack Now

Useful Resources for CI/CD

Understanding CI/CD

Tools and Comparisons

Best Practices, Tips, and Tricks

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Understanding CI, CD, and CT in DevOps