3-Tier Blog API System

A containerized 3-tier web application consisting of:

1. Backend API (Go) - serves REST responses with blog titles
2. Database (MySQL) - stores blog data
3. Proxy (Nginx) - exposes API over HTTPS

Architecture

Client → Nginx (HTTPS) → Backend API (Go) → MySQL Database

File structure

├── backend
│   ├── db-password.txt
│   ├── docker-compose.yaml
│   ├── Dockerfile
│   ├── go.mod
│   ├── go.sum
│   ├── main.go
│   └── README.md
├── docker-compose.yaml
├── git-push.sh
├── imgs
│   ├── 1.png
│   ├── 2.png
│   ├── 3.png
│   └── 4.png
├── k8s
│   ├── backend_deployment.yaml
│   ├── backend_service.yaml
│   ├── database_deployment.yaml
│   ├── db-data-pvc.yaml
│   ├── db-data-pv.yaml
│   ├── db-secret.yaml
│   ├── db-service.yaml
│   ├── nginx-configmap.yaml
│   ├── proxy_deployment.yaml
│   ├── proxy_nodeport.yaml
│   └── README.md
├── nginx
│   ├── Dockerfile
│   ├── generate-ssl.sh
│   ├── nginx.conf
│   └── README.md
├── project1.pdf
└── README.md

5 directories, 30 files

---

Test Docker Backend Image

read the README.md in the backend

---

Test Docker Compose

$ docker compose up -d

$ curl http://localhost:10000

["Blog post #0","Blog post #1","Blog post #2","Blog post #3","Blog post #4"]

---

Build and Push nginx image

• read the README.md in the nginx To build and push the image

docker compose up -d

---

Deploy To K8s Cluster

read the README.md in the k8s to deploy

I'm using minikube

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Task 2 (optional)

Create docker compose (docker-compose-networks.yaml) setup with 3 separate networks for each container and make them communicate with each other(They can see each other) with their names, without a shared network

run:

docker compose -f docker-compose-networks.yaml up
# OR
docker compose -f docker-compose-networks.yaml up -d 

clean:

docker compose -f docker-compose-networks.yaml down

How it works:

• Three Separate Networks

  • db-network: Only mysql-db container
  • backend-network: Only go-backend container
  • nginx-network: Only nginx container

• Each container is completely isolated in its own network. no direct container-to-container communication.

• Containers Communicate Through the Host Gateway

  •  extra_hosts:
     - "go-backend:172.17.0.1"  # Maps service name to Docker host IP
     - "db:172.17.0.1"
    

  • 172.17.0.1 is Docker's default bridge gateway IP on Linux
  • This allows containers to resolve service names to the host IP

Communication Flow

• nginx config: server go-backend:10000;
• DNS resolution: go-backend → 172.17.0.1 (via extra_hosts)
• Connection: nginx connects to 172.17.0.1:10000
• Host routing: Docker host routes :10000 → Test-GoApp:8000
• Response: Go app responds back through the same path

Network Architecture

┌─────────────────┐    ┌─────────────────┐    ┌─────────────────┐
│   nginx-proxy   │    │   Test-GoApp    │    │   mysql-db      │
│  (nginx-network)│    │(backend-network)│    │  (db-network)   │
└─────────────────┘    └─────────────────┘    └─────────────────┘
         │                       │                       │
         │                       │                       │
    ┌────▼────┐             ┌────▼────┐             ┌────▼─────┐
    │nginx-net│             │backend- │             │db-network│
    │172.30.x │             │net      │             │172.28.x  │
    │         │             │172.29.x │             │          │
    └─────────┘             └─────────┘             └──────────┘
         │                       │                       │
         └───────────────────────┼───────────────────────┘
                                 │
                        ┌────────▼─────────┐
                        │  Docker Host     │
                        │   172.17.0.1     │
                        │                  │
                        │ Port Mappings:   │
                        │ :80 → nginx:80   │
                        │ :443→ nginx:443  │
                        │ :10000→ go:8000  │
                        │ :3306→ mysql:3306│
                        └──────────────────┘