CD_pipeline_setup

• Requirements:

    Python 3 
    Flask : pip3 install Flask
    Docker : can be read at the link given below
    Jenkins
    JDK
    Ngrok
  

• To set up a CD pipeline, first we'll create a basic web app written in Python's Flask, for this execute the following commands:

  $ mkdir pythonWebApp
  $ cd pythonWebApp
  $ mkdir app
  $ touch app/app.py
  $ vi app/app.py
  

  In `app.py`, paste the following code:
   
  from flask import Flask
    
    app = Flask(__name__)
    
    
    @app.route('/hello')
    def hello_world():
        return "Hello World! How are you doing?"
    
    
    if __name__ == "__main__":
        app.run(host='0.0.0.0', port=8008, debug=True)
  
  

  Save the file and then create a Dockerfile in the pythonWebApp directory (not in the app sub-folder):

  FROM python:3
  
  #creates a new directory myApp/app in the container
  WORKDIR myApp/app
  RUN apt update
  RUN pip3 install flask
  
  COPY app .
  
  EXPOSE 8008
  
  CMD ["python", "app.py", "runserver", "0.0.0.0:8008"]
  
  

• Run, docker build -t myapp . in the parent folder (i.e. pythonWebApp)

• After successful completion of the build, run docker images to view the image myapp.

• Run a container using this image : docker run -p 8008:8008 myapp, use -p flag and specify port 8080, so that we can access the container on the 8080 port of our host.

• Open your browser, and enter the localhost url along with the port 8080, image below:

• 

• Congrats! your first containerized application is successful.

Setting up a CD pipeline using Jenkins:

• Install Java (preferably OpenJDK-17): sudo apt-get install openjdk-17-jdk, then test it using java -version.
• Later you may add Java to global environment variables so that other applications can access it.
• Install git
• Install Jenkins:

  $ wget -q -O - https://pkg.jenkins.io/debian-stable/jenkins.io.key |sudo gpg --dearmor -o /usr/share/keyrings/jenkins.gpg
  $ sudo sh -c 'echo deb [signed-by=/usr/share/keyrings/jenkins.gpg] http://pkg.jenkins.io/debian-stable binary/ > /etc/apt/sources.list.d/jenkins.list'
  $ sudo apt install jenkins
  $ #enable and start
  $ sudo systemctl enable jenkins
  $ sudo systemctl start jenkins
  $ sudo systemctl status jenkins
  

• Allow Jenkins default port 8080:

  $ sudo ufw allow 8080
  $ sudo ufw status
  $ sudo ufw enable
  $ sudo ufw status
  

• After this, login in into Jenkins by going to it’s default link: http://127.0.0.1:8008, here enter the initialAdminPassword.
• Create a new pipeline project, and configure it as a github project:
• After this, write a Jenkinsfile in your project's root, like this:

• pipeline {
    agent any
  
    stages {
        stage("Clone Code") {
            steps {
                echo "Cloning the code"
                git url: "https://github.com/lakshya-chopra/pythonWebApp.git", branch: "main"
            }
        }
  
        stage("Build") {
            steps {
                echo "Building the Docker image"
                sh "docker build -t myapp ."
            }
        }
  
  
        stage("Deploy") {
            steps {
                echo "Deploying the container"
                sh "docker run -p 80:80 myapp"
                
            }
        }
    }
  }
  

  • Also do this:

  • 

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GitHub Webhook setup:

• In your Jenkins dashboard, go to Manage Jenkins -> System Configuration and from there set up the Github server with your credentials:

• 

• In your github webhook, you'll need to have a public web url, where github can post data on, this can be done via ngrok or by using any public cloud provider.

  • Install ngrok via: sudo snap install ngrok
  • Create a new ngrok account, and then run ngrok http 80 which directs your the public url -> localhost:80
  • Simulatenously, deploy the app using docker run -it -p 80:80 myapp, and check whether it's accessible on ngrok's website or not.

• Navigate the settings of your github project, and create a webhook which will send a notification to your app whenever you do some changes to your github repo (you may disable SSL if your payload url is not https secure)

• 

• Finally, build the pipeline and do some changes to your github code and see whether you're receiving the notifications or not:

• like this:

• 

• You might face some errors while building, so ensure that git is properly configured (path correctly set in the Git plugin) & that your github credentials are correct and available. Also ensure that your Github branch is named as main, or you'll have to change the jenkins config.

• Check this for setting Git exe

• And this too

• Ensure that Jenkins isn't blocked by some firewall.

• You may, also tick this option to stop the old builds, whenever you build a new one, as this can lead to port conflicting in docker.

•