🚀 DevOps in Action: How CI/CD Makes Life Easier

CI/CD pipelines are like having a robot assistant for your deployments. In this post, I break down how automating builds and deployments saves time, reduces errors, and keeps your team sane. Walk through the project with step-by-step instructions on completing it.

Continuous Integration and Continuous Deployment (CI/CD) pipelines streamline the software development process by automating the building, testing, and deployment of applications. In this blog, we’ll set up a CI/CD pipeline for a simple Flask application using Jenkins, Docker, and GitHub. We’ll also expose our local Jenkins instance to the Internet using ngrok to receive webhook triggers.

Table of Contents

Prerequisites
Creating the Flask Application
Writing the Dockerfile
Installing and Configuring Jenkins
Creating a Jenkins Pipeline
Setting Up GitHub Webhooks
Exposing Jenkins to the Internet Using ngrok
Configuring Firewall Rules
Testing the Pipeline
Conclusion

1. Prerequisites

Before starting, ensure you have the following installed on your system:

Ubuntu Linux (VM or local machine)
Python 3
Git
Docker
Jenkins
ngrok (for exposing Jenkins to the public)

2. Creating the Flask Application

Create a directory for your Flask app and the following files:

app.py


Copied!from flask import Flask

app = Flask(__name__)

@app.route('/')

def home():

    return "Hello, World! This is our CI/CD Pipeline demo."

if __name__ == "__main__":

    app.run(host='0.0.0.0', port=5000)
from flask import Flask

app = Flask(__name__)

@app.route('/')

def home():

    return "Hello, World! This is our CI/CD Pipeline demo."

if __name__ == "__main__":

    app.run(host='0.0.0.0', port=5000)

requirements.txt


Copied!flask
flask

3. Writing the Dockerfile

Create a Dockerfile to containerize the Flask application.

Dockerfile


Copied!FROM python:3.9

WORKDIR /app

COPY requirements.txt .

RUN pip install -r requirements.txt

COPY app.py .

EXPOSE 5000

CMD ["python", "app.py"]
FROM python:3.9

WORKDIR /app

COPY requirements.txt .

RUN pip install -r requirements.txt

COPY app.py .

EXPOSE 5000

CMD ["python", "app.py"]

4. Installing and Configuring Jenkins

Step 1: Install Jenkins

Add the Jenkins repository and install Jenkins:

bash


Copied!wget -q -O - https://pkg.jenkins.io/debian/jenkins.io.key | sudo apt-key add -

sudo sh -c 'echo deb http://pkg.jenkins.io/debian-stable binary/ > /etc/apt/sources.list.d/jenkins.list'

sudo apt update

sudo apt install jenkins -y
wget -q -O - https://pkg.jenkins.io/debian/jenkins.io.key | sudo apt-key add -

sudo sh -c 'echo deb http://pkg.jenkins.io/debian-stable binary/ > /etc/apt/sources.list.d/jenkins.list'

sudo apt update

sudo apt install jenkins -y

Start and enable Jenkins:


Copied!sudo systemctl start jenkins

sudo systemctl enable jenkins
sudo systemctl start jenkins

sudo systemctl enable jenkins

Access Jenkins:
Open http://localhost:8080 and follow the instructions to unlock Jenkins.

5. Creating a Jenkins Pipeline

Step 1: Create a Jenkinsfile

Create a Jenkinsfile in your project root directory:


Copied!pipeline {

    agent any

    environment {

        DOCKER_IMAGE = "my-flask-app"

        DOCKER_TAG = "${env.BUILD_NUMBER}"

    }

    stages {

        stage('Checkout Code') {

            steps {

                git branch: 'main', url: 'https://github.com/yourusername/my-flask-app.git'

            }

        }

        stage('Build Docker Image') {

            steps {

                sh "docker build -t ${DOCKER_IMAGE}:${DOCKER_TAG} ."

            }

        }

        stage('Remove Existing Container') {

            steps {

                sh '''

                docker ps -a | grep flask-app && docker stop flask-app && docker rm flask-app || true

                '''

            }

        }

        stage('Run New Container') {

            steps {

                sh "docker run -d -p 5000:5000 --name flask-app ${DOCKER_IMAGE}:${DOCKER_TAG}"

            }

        }

        stage('Clean Up Old Images') {

            steps {

                sh "docker image prune -f"

            }

        }

    }

    post {

        success {

            echo 'Deployment succeeded!'

        }

        failure {

            echo 'Deployment failed. Please check the logs.'

        }

    }

}
pipeline {

    agent any

    environment {

        DOCKER_IMAGE = "my-flask-app"

        DOCKER_TAG = "${env.BUILD_NUMBER}"

    }

    stages {

        stage('Checkout Code') {

            steps {

                git branch: 'main', url: 'https://github.com/yourusername/my-flask-app.git'

            }

        }

        stage('Build Docker Image') {

            steps {

                sh "docker build -t ${DOCKER_IMAGE}:${DOCKER_TAG} ."

            }

        }

        stage('Remove Existing Container') {

            steps {

                sh '''

                docker ps -a | grep flask-app && docker stop flask-app && docker rm flask-app || true

                '''

            }

        }

        stage('Run New Container') {

            steps {

                sh "docker run -d -p 5000:5000 --name flask-app ${DOCKER_IMAGE}:${DOCKER_TAG}"

            }

        }

        stage('Clean Up Old Images') {

            steps {

                sh "docker image prune -f"

            }

        }

    }

    post {

        success {

            echo 'Deployment succeeded!'

        }

        failure {

            echo 'Deployment failed. Please check the logs.'

        }

    }

}

Step 2: Create a Pipeline Job in Jenkins

Go to Jenkins Dashboard > New Item.
Enter a job name (e.g., my-flask-app-pipeline).
Select Pipeline and click OK.
In the Pipeline section, set the Definition to Pipeline script from SCM.
Add your Git repository URL and branch.
Click Save.

6. Setting Up GitHub Webhooks

Go to Your GitHub Repository > Settings > Webhooks.
Click Add webhook.
Payload URL:

vbnet


Copied!http://your-public-ngrok-url/github-webhook/
http://your-public-ngrok-url/github-webhook/

Content type: application/json
Select Just the push event.
Click Add webhook.

7. Exposing Jenkins to the Internet Using ngrok

Install ngrok:

bash


Copied!wget https://bin.equinox.io/c/bNyj1mQVY4c/ngrok-stable-linux-amd64.zip

unzip ngrok-stable-linux-amd64.zip

sudo mv ngrok /usr/local/bin
wget https://bin.equinox.io/c/bNyj1mQVY4c/ngrok-stable-linux-amd64.zip

unzip ngrok-stable-linux-amd64.zip

sudo mv ngrok /usr/local/bin

Authenticate ngrok:

bash


Copied!ngrok config add-authtoken <your_auth_token></your_auth_token>
ngrok config add-authtoken <YOUR_AUTH_TOKEN>

Start ngrok:

bash


Copied!ngrok http 8080
ngrok http 8080

Copy the Public URL provided by ngrok and use it for the GitHub webhook.

8. Configuring Firewall Rules

For Ubuntu (ufw)

Enable the firewall:

bash


Copied!sudo ufw enable
sudo ufw enable

Allow port 5000 (for Flask app):

bash


Copied!sudo ufw allow 5000
sudo ufw allow 5000

Allow port 8080 (for Jenkins):

bash


Copied!sudo ufw allow 8080
sudo ufw allow 8080

9. Testing the Pipeline

Make a Change in Your Flask App:

bash


Copied!git add app.py

git commit -m "Test CI/CD pipeline"

git push origin main
git add app.py

git commit -m "Test CI/CD pipeline"

git push origin main

Check Jenkins:
The pipeline should trigger automatically, build the Docker image, and deploy the Flask app.
Access the Flask App:
Open your browser and go to:

arduino


Copied!http://your-vm-ip:5000
http://your-vm-ip:5000

10. Conclusion

Congratulations! 🎉 You have successfully set up a CI/CD pipeline for your Flask app using Jenkins, Docker, and GitHub. This setup ensures that every time you push changes to your GitHub repository, Jenkins automatically builds a new Docker image and deploys it. Using ngrok allows you to expose your local Jenkins instance to the public Internet for webhook integration.

This CI/CD pipeline can be extended to include automated testing, linting, and more advanced deployment strategies.

🔗 Check my GitHub repo for up-to-date codes.

Happy coding! 🚀

🚀 DevOps in Action: How CI/CD Makes Life Easier

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