Web-server X Load Balancers

Load balancers are crucial in mission-critical environments where multiple customers need to access data/resources across various regions.

I set up a CI/CD pipeline with GitHub Actions that deployed a containerized application on multiple servers. The load balancer using Caddy was set up to distribute the traffic between the servers.

Receiving this task, it seemed a little overwhelming but I was able to break it down into different sections using a method I learned -> DevSecOps. The idea is to have the project broken into manageable bits. I'll be using this method to walk you through my project!

Breaking down the task into bits helped me to focus on one section at a time and ensure that I covered all the ‘coverables’

Join me as we go into detail on this exciting project!

Devsecops

Before any process can be automated, there must be some assurance that things and services work as they should. I started by manually containerizing my application and ensuring it ran on the server.

My application is a Django app, so this part will differ depending on the peculiarities of you stack and application.

Dockerfile

FROM python:3.9
ENV PYTHONUNBUFFERED 1
RUN mkdir /code
WORKDIR /code
COPY requirements.txt /code/
RUN pip install -r requirements.txt
COPY . /code/
CMD ["python3.9", "manage.py", "runserver", "0.0.0.0:8000"]

Although the details of the Dockerfile are outside the scope of this article, you can refer to Docker's documentation. I also found this article quite useful: Docker Django Deployment

My Web application also has a DB service, so I used Docker Compose to manage both containers.

compose.yaml

services:
  db:
    image: nouchka/sqlite3:latest
    volumes:
      - ./data/db:/root/db
    environment:
      - SQLITE3_DB=db.sqlite3
  web:
    build: .
    command: python3.9 manage.py runserver 0.0.0.0:8000
    volumes:
      - .:/code
    ports:
      - "8000:8000"
    depends_on:
      - db

To learn more about Docker Compose, check the official documentation. You can also refer to this article. Again, this is not applicable to other types of applications. Link to Article

After testing the dockerization, the next thing to work on was the Load Balancer. There are a number of tools to choose from, but I chose to work with Caddy

Caddyfile

:80 {
  reverse_proxy [11.11.11.11:8000 22.22.22.22:8000] {  # Ip addresses go here :)
    lb_policy random
}
}

# File is stored at /etc/caddy/Caddyfile by default

random is the Load-balancing algorithm I decided to work with ;). Please refer to the documentation for more details. That concludes the Dev part of this project.

devSecops

Aside from the fact that my servers (EC2 instances) had Security Groups, I decided to add an extra layer of security by setting up a Firewall for the servers.

There wasn't really much to it, I just decided the ports I wanted open on the OS level.

devsecOps

The final part of this project was to include as much automation as possible to streamline deployment. The best/easiest choice was to use GitHub actions.

I set up the pipeline to be triggered when the codebase changed. The workflow rebuilt the application image, pushed to Docker Hub, pulled the image on my servers and started the containers.

After a lot of work on this part, I got something that worked for me.

.github/workflows/main.yaml

name: Build to servers

on:
  push:
    branches: [main]

jobs:
  build:
    runs-on: ubuntu-latest
    strategy:
      matrix:
        server: [11.11.11.11, 22.22.22.22]
    env:
      EC2_SSH_PRIVATE_KEY: ${{ secrets.EC2_SSH_PRIVATE_KEY }}
      EC2_USERNAME: ${{ secrets.EC2_USERNAME }}
      DOCKER_USERNAME: ${{ secrets.DOCKER_USERNAME }}
      DOCKER_PASSWORD: ${{ secrets.DOCKER_PASSWORD }}


    steps:
      - name: Checkout source
        uses: actions/checkout@v3

      - name: Login to Docker Hub
        run: docker login -u ${{ secrets.DOCKER_USERNAME }} -p ${{ secrets.DOCKER_PASSWORD }}

      - name: Build Docker Image
        run: |
          docker compose up --build -d
          docker compose down

      - name: Tag the docker image
        run: docker tag mockstack-overflow-web ${{ secrets.DOCKER_USERNAME }}/mockstack-overflow-web:latest

      - name: Publish image to docker hub
        run: docker push fifss/mockstack-overflow-web:latest

      - name: Login to servers
        uses: omarhosny206/setup-ssh-for-ec2@v1.0.0
        with:
            EC2_SSH_PRIVATE_KEY: $EC2_SSH_PRIVATE_KEY
            EC2_URL: ${{ matrix.server }}

      - name: Run docker commands on server 1 & 2
        run: |
          ssh -o StrictHostKeyChecking=no $EC2_USERNAME@${{ matrix.server }} << EOF
            docker login -u $DOCKER_USERNAME -p $DOCKER_PASSWORD
            docker pull $DOCKER_USERNAME/mockstack-overflow-web:latest
            docker stop mockstack-overflow-web || true
            docker rm mockstack-overflow-web || true
            docker run -d --name mockstack-overflow-web -p 8000:8000 $DOCKER_USERNAME/mockstack-overflow-web:latest
          EOF

Make sure you have your secrets stored on GitHub. To do this, in your GitHub repository, go to Settings -> Secrets & variables -> Actions -> New Repository secret

For me, my EC2_SSH_PRIVATE_KEY was the private key for my servers that I downloaded while setting up the server.

I hope you've been able to learn a thing or two 😊

Feel free to leave any questions you have for me in the comments.

My name is Fife, let's connect and work together 🤝🏾

Btw, this is my debut in this community 😅 not too shabby huh?

Reference: Cover Image