FastAPI to ECS the Smart Way: Load Balanced & Custom Branded

Deploying a containerized solution on AWS using Elastic Container Service (ECS) is a powerful approach for scalable backend applications. Combining FastAPI with ECS and Fargate ensures high performance while minimizing operational overhead. Here’s how to implement this setup effectively.

Key Components

1. FastAPI: A modern Python framework for building APIs with automatic Swagger/OpenAPI documentation.
2. Amazon ECS: Manages container orchestration without requiring Kubernetes expertise.
3. AWS Fargate: Serverless compute engine for containers, eliminating EC2 management.
4. Application Load Balancer (ALB): Distributes traffic across containers for high availability.

You Should Know:

1. FastAPI Containerization

Create a `Dockerfile` for FastAPI:

FROM python:3.9-slim 
WORKDIR /app 
COPY requirements.txt . 
RUN pip install --no-cache-dir -r requirements.txt 
COPY . . 
CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "80"] 

Build and test locally:

docker build -t fastapi-app . 
docker run -p 80:80 fastapi-app 

#### **2. AWS ECS Setup**

• Push the Docker image to Amazon ECR:

  aws ecr create-repository --repository-name fastapi-repo 
  docker tag fastapi-app:latest <ACCOUNT_ID>.dkr.ecr.<REGION>.amazonaws.com/fastapi-repo:latest 
  aws ecr get-login-password | docker login --username AWS --password-stdin <ACCOUNT_ID>.dkr.ecr.<REGION>.amazonaws.com 
  docker push <ACCOUNT_ID>.dkr.ecr.<REGION>.amazonaws.com/fastapi-repo:latest 
  

• Define an ECS Task Definition (JSON) specifying Fargate launch type, CPU/memory, and the ECR image.

#### **3. Configure ALB for ECS**

• Create a Target Group for ECS tasks.
• Set up ALB listeners (HTTP/HTTPS) routing to the Target Group.
• Ensure security groups allow traffic between ALB and ECS tasks.

#### **4. Deploy the Service**

• Create an ECS Service linked to the ALB, enabling auto-scaling policies.
• Monitor using CloudWatch Logs:

  aws logs tail /ecs/fastapi-service --follow 
  

### **What Undercode Say**

This architecture leverages AWS serverless containers for cost efficiency and scalability. Key Linux/Windows commands to enhance your workflow:

• Linux Networking:

  netstat -tuln | grep 80 # Check port usage 
  curl http://localhost/docs # Test FastAPI locally 
  

• AWS CLI:

  aws ecs describe-services --cluster my-cluster --services my-service 
  aws elbv2 describe-load-balancers --names my-alb 
  

• Windows (PowerShell):

  Test-NetConnection -ComputerName <ALB_DNS> -Port 80 
  Get-ECSTaskDefinition -TaskDefinition my-task 
  

For further reading, refer to the original guide: FastAPI to ECS the Smart Way.

### **Expected Output:**

A fully load-balanced FastAPI backend running on AWS ECS with zero server management.

References:

Reported By: Darryl Ruggles – Hackers Feeds
Extra Hub: Undercode MoN
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