dependencies.txt

========================================================= JENKINS WITH CI/CD ============================================================

Here’s a step-wise guide to set up a Python application with tests using *pytest, integrate it with Jenkins, and connect it to GitHub webhooks using **ngrok*.

---

### Step-Wise Guide:

#### *1. Set Up Jenkins*
1. *Install Jenkins*:
   - Download and install Jenkins.
   - Ensure Jenkins is running locally, e.g., on port 8080.

2. *Install Plugins*:
   - Go to *Manage Jenkins > Manage Plugins > Available Tab*.
   - Install the following plugins:
     - *GitHub Integration Plugin*
     - *Pipeline Plugin*

3. *Create a Pipeline Job*:
   - Go to *Jenkins Dashboard > New Item > Pipeline*.
   - Name the job, e.g., GitHub_Webhook_Test_Pipeline.
   - Choose from Build triggers Github hook trigger for GITsce pooling
---

#### *2. Create Python Application and Tests*

1. *Set Up Project Structure*:
   plaintext
   my_python_app/
   ├── app/
   │   ├── __init__.py
   │   ├── main.py
   ├── tests/
   │   ├── __init__.py
   │   ├── test_main.py
   ├── requirements.txt
   ├── Jenkinsfile
   ├── pytest.ini
   ├── README.md
   

2. *Sample Python Code (Application)*: app/main.py
   python
   def add(a, b):
       """Adds two numbers."""
       return a + b

   def subtract(a, b):
       """Subtracts two numbers."""
       return a - b
   

3. *Sample Tests (Using pytest)*: tests/test_main.py
   python
   from app.main import add, subtract

   def test_add():
       assert add(3, 5) == 8
       assert add(-1, 1) == 0

   def test_subtract():
       assert subtract(10, 5) == 5
       assert subtract(0, 5) == -5
   

4. *Requirements File*: requirements.txt
   plaintext
   pytest
   

5. *pytest Configuration File*: pytest.ini
   plaintext
   [pytest]
   addopts = -v
   testpaths = tests
   

---

#### *3. Configure Jenkins Pipeline*

1. *Jenkinsfile*: Jenkinsfile
   
pipeline {
    agent any
    stages {
        stage('Clone Repository') {
            steps {
                git branch: 'main', url: 'https://github.com/username/my_python_app.git'
            }
        }
        stage('Install Dependencies') {
            steps {
                sh 'pip install -r requirements.txt'
            }
        }
        stage('Run Tests') {
            steps {
                sh 'pytest'
            }
        }
    }
}
   

2. *Commit and Push*:
   - Commit the Jenkinsfile and Python project to a GitHub repository.

---

#### *4. Configure Ngrok*
1. *Download ngrok*:
   - Download and install ngrok from [ngrok.com](https://ngrok.com/).

  - wget https://bin.equinox.io/c/bNyj1mQVY4c/ngrok-v3-stable-linux-amd64.tgz
  - sudo tar xvzf ./ngrok-v3-stable-linux-amd64.tgz -C /usr/local/bin

2. *Authenticate ngrok*:
   bash
   ngrok authtoken <your-authtoken>
   

3. *Run ngrok*:
   bash
   ngrok http 8080
   
   Copy the HTTPS URL (e.g., https://<random-subdomain>.ngrok.io).

---

#### *5. Configure GitHub Webhook*
1. Go to your repository’s *Settings > Webhooks*.
2. Click *Add Webhook*.
3. Set the *Payload URL*:
   
   https://<random-subdomain>.ngrok.io/github-webhook/
   
4. Set *Content Type* to application/json.
5. Select the event: *Just the push event*.
6. Save the webhook.

---

#### *6. Run the Pipeline*
1. Push any change to the repository.

echo "# New change" >> README.md
git add .
git commit -m "Testing webhook"
git push origin main

                       
2. GitHub will send a webhook to Jenkins via the ngrok URL.
3. Jenkins will:
   - Clone the repository.
   - Install dependencies.
   - Run the pytest tests.
4. View results in Jenkins.

---

### Example Output:
#### *Jenkins Console Output*

[Pipeline] Start of Pipeline
[Pipeline] stage (Clone Repository)
Cloning repository...
[Pipeline] stage (Install Dependencies)
Installing pytest...
[Pipeline] stage (Run Tests)
Running pytest...
tests/test_main.py::test_add PASSED
tests/test_main.py::test_subtract PASSED


Now your setup is complete with a Python app, pytest for testing, Jenkins for CI/CD, and GitHub webhooks for automation!

(LINUX COMMANDS)
hostname -I --> ip address
whoami ---> username

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------

#Q3 SSH REMOTE-LOCAL CONNECTION


ssh-keygen -t rsa -b 2048
ssh-copy-id username@ip
--create a test.sh in remote system
ssh username@ip 'bash ~/test.sh'

To transfer file from remote to local: (write this command in a script file--> script.sh)
scp "username@ip":"filename_remote" "filename_local"
Then run the script file ---> bash script.sh

To send file from local to remote: (write this command in a script file--> script.sh)
scp "filename_local" "username@ip":"filename_remote"
Then run the script file ---> bash script.sh

to install SSH(if not present):

sudo apt install openssh-server
sudo systemctl start ssh
sudo systemctl enable ssh
sudo apt install openjdk-17-jdk

-----------------------------------------------------------------------------------------------------------------------------------------------------------------

#Q4 DOCKER 


(!CHANGES!) THERE ARE TWO COMMANDS (sudo snap install docker and sudo apt install docker.io)
sudo snap install docker.io
docker build -t myapp .

###############################################################################################

If u see docker.sock error, cd ../.. (return to base directory)
cd /var
cd /run
sudo chmod 666 docker.sock
(!CHANGES!) (This can be modified to sudo chmod 666 /var/run/docker.sock)

Another way to solve permission error
sudo usermod -aG docker$USER
newgrp docker

################################################################################################

docker run -d -p 5000:5000 myapp

docker tag myapp/app deepsh0203/app:latest
docker push deepsh0203/app:latest
docker pull deepsh0203/app:latest

Incase if Docker push,pull mentioned in question
deepsh0203 is Dockerhub username, create one for u
myapp-repo name
app-image name



app.py :

from flask import Flask

app = Flask(__name__)

@app.route('/')
def hello():
    return "Hello from Flask!"

if __name__ == "__main__":
    app.run(host="0.0.0.0",port=5000)
(!CHANGES!) (You can add endpoints if u want)


CODE2 app.py (GET METHOD): 

from flask import Flask,jsonify

app = Flask(__name__)

students = [
    {"id":1,"name":"Dennis","age":20,"Major":"Computer Science"},
    {"id": 2, "name": "Harish", "age": 20, "major": "Mathematics"},
    {"id": 3, "name": "Badri", "age": 20, "major": "Machine Learning"}
]


@app.route("/")
def home():
    return "Hello World"

@app.route("/students",methods=["GET"])
def getStudents():
    return jsonify(students)

@app.route("/students/<int:studentId>",methods=["GET"])
def getStudent(studentId):
    student=None
    for i in students:
        if i["id"]==studentId:
            student=i
            break
    if student!=None:
        return jsonify(student)
    else:
        return jsonify({"error":"Student not found"}),404


if __name__=='__main__':
    app.run("0.0.0.0",5000)


Dockerfile:

# Use the official Python image
FROM python:3.9

# Set the working directory in the container
WORKDIR /app

# Copy the current directory contents into the container
COPY . /app

# Install any needed packages specified in requirements.txt
RUN pip install -r requirements.txt

# Make port 5000 available to the world outside this container
EXPOSE 5000

# Define environment variable
ENV NAME=FlaskApp

# Run app.py when the container launches
CMD ["python", "app.py"]


requirements.txt:

Flask==2.3.3
Werkzeug==2.3.3
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
#Q6 LOAD BALANCING
========================================================LOGIC 1============================================================================

app.py:

from flask import Flask, jsonify
import os

app = Flask(__name__)

@app.route('/')
def index():
    return jsonify({
        "message": "Hello from Flask instance",
        "instance": os.getenv('INSTANCE_NAME', 'Unknown')
    })

if __name__ == "__main__":
    app.run(host='0.0.0.0', port=5000)

docker-compose.yml:

version: '3.8'

services:
  flask1:
    image: flask-app
    environment:
      - INSTANCE_NAME=Flask_Instance_1
    ports:
      - "5001:5000"

  flask2:
    image: flask-app
    environment:
      - INSTANCE_NAME=Flask_Instance_2
    ports:
      - "5002:5000"

  flask3:
    image: flask-app
    environment:
      - INSTANCE_NAME=Flask_Instance_3
    ports:
      - "5003:5000"

Dockerfile:

# Use Python as the base image
FROM python:3.9-slim

# Set the working directory
WORKDIR /app

# Copy files to the container
COPY . .

# Install dependencies
RUN pip install flask

# Expose the Flask port
EXPOSE 5000

# Start the Flask app
CMD ["python", "app.py"]

Commands to run:

sudo apt-get install nginx
sudo apt-get install apache2-utils

docker build -t flask-app .
docker-compose up -d

nginx.conf:


#user  nobody;
worker_processes  1;


#pid        logs/nginx.pid;


events {}

http {
    log_format minimal '$remote_addr $upstream_addr';

    access_log <create a custom access.log file in your folder> (eg: /Users/akash/load/custom_access.log) ;
create a custom.log file in your folder
    upstream flask_backend {
        server localhost:5001;
        server localhost:5002;
        server localhost:5003;
    }

    server {
        listen 80;

        location / {
            proxy_pass http://flask_backend;
        }
    }
}


===============================================================LOGIC 2=====================================================================

sudo apt-get install nginx
sudo apt-get install apache2-utils

docker build -t flaskapp5 .
docker run -d -p 5001:5000 flaskapp5
docker run -d -p 5002:5000 flaskapp5
docker run -d -p 5003:5000 flaskapp5

ab -n 1000 -c 100 http://localhost:5001/ (takes more time)

code /etc/nginx/nginx.conf
sudo chmod o+w /etc/nginx/nginx.conf
sudo rm /etc/nginx/sites-enabled/default

sudo nginx -t
sudo systemctl restart nginx

curl http://localhost/
ab -n 1000 -c 100 http://localhost/ (takes lesser time)

docker logs containerID

When a text editor or vsc opens, type this:

http {
upstream flaskapp {
server localhost:5001;
server localhost:5002;
server localhost:5003;
}
server {
listen 80;
location / {
proxy_pass http://flaskapp;
}
}
}