FastAPI URL Service

Create a service deployed on AWS Lambda that provides access to private S3 bucket files through pre-signed urls tracking usage based on token authentication.

Stack

• Application core: Python + FastAPI
• Package manager: Poetry
• Testing: Pytest + Moto
• Infrastructure management: Terraform
• Cloud services: AWS Lambda + DynamoDB + S3

Requirements

Core

• Setup package manager
• Install FastAPI
• Create dummy endpoint
• Setup S3 integration
• Create endpoint to list files
• Create endpoint to retrieve pre-signed url for a specific file
• Setup linting
• Setup testing
• Improve testing to use factory boy
• Improve testing by using moto to mock AWS services
• Setup persistence layer (DynamoDB?)
• Create endpoint to add new user
• Setup token auth to API
• Create usage measurements based on token auth

Infra

• Setup base terraform for managing resources
• Setup S3 resource (make it fully private to avoid public access)
• Setup DynamoDB resource
• Setup FastAPI deploy to AWS Lambda
• Adjust role to include S3 and DynamoDB permissions
• Setup CI/CD pipeline
• Setup pre-commit hooks
• Integrate project with localstack for easy local testing

Architecture

• Improve code architecture by including service/repo layers

Improvements

• Avoid local env from using real resources
• Include .env variables for deployed env

Bugs

• Redirect loop happening on the deployed version of the app

Database

For this project, a single-table approach was chosen to be used on DynamoDB, for this, listing the use-cases is very important.

Use cases

• Check if user token exists (read)
• Register new user (write)
  • Email must be unique across all users
• Register usage for each new request (write)
• Fetch usage based on token (read)