PyRestApi CDK Project

This project deploys a serverless REST API on AWS using AWS CDK (Cloud Development Kit) in Python. The API leverages API Gateway, Lambda functions, and DynamoDB to provide a simple REST interface for managing employee records.

Architecture

Features

• API Gateway: Exposes a REST API with CORS enabled, allowing GET and POST methods.
• Lambda Function: Processes API requests to add new records or fetch existing records by ID.
• DynamoDB Table: Stores employee data, with an auto-generated unique ID for each record.

Project Structure

• app.py: Entry point for the CDK application.
• PyRestApiStack: Defines the AWS resources and connections between them.
• services/index.py: Lambda function handler and supporting functions.

Stack Components

• DynamoDB Table: Named EmplTablePy, with id as the partition key, and provisioned for on-demand billing.
• Lambda Function: Named EmplLambda, using Python 3.11 runtime. Configured with environment variables to access the DynamoDB table and uses index.handler as the entry point.
• API Gateway: Exposes the REST API with two endpoints:
  • POST /empl: Adds a new employee record.
  • GET /empl?id={id}: Fetches an employee record by id.

Usage

Base URL: https://51pl8svxec.execute-api.us-east-1.amazonaws.com/prod/

1. POST /empl
   Add a new employee record.

   • Endpoint: POST https://51pl8svxec.execute-api.us-east-1.amazonaws.com/prod/empl
   • Request Body (JSON):

     {
       "name": "John Doe",
       "position": "Software Engineer",
       "department": "Engineering"
     }

   • Response (JSON):

     {
       "id": "generated-unique-id"
     }

2. GET /empl?id={id}
   Fetch an employee record by ID.

   • Endpoint: GET https://51pl8svxec.execute-api.us-east-1.amazonaws.com/prod/empl?id={id}
   • Query Parameter: id (UUID of the employee record)
   • Response (JSON):

     {
       "id": "generated-unique-id",
       "name": "John Doe",
       "position": "Software Engineer",
       "department": "Engineering"
     }

   • Error Response:
     • Status Code: 404 Not Found
     • Response Body:

       {
         "error": "Not found"
       }

Lambda Code Overview

The Lambda handler function (index.handler) processes incoming HTTP requests based on the method:

• POST: Calls add_new_item() to insert a new record with a generated UUID.
• GET: Calls get_item_by_id() to retrieve a record by its unique ID.
• Helper Functions:
  • generate_response(): Standardizes API responses with CORS headers.
  • add_new_item() and get_item_by_id(): Interact with DynamoDB.

Deployment Instructions

1. Install AWS CDK

   npm install -g aws-cdk

2. create and activate a Virtual Environment (Optional but recommended)

   python3 -m venv .venv && source .venv/bin/activate
   

3. Install Python dependencies

   pip install -r requirements.txt
   

4. Deploy the stack

   cdk deploy
   

References

This project was inspired by the Udemy course:
Course Title:AWS CDK for professionals (Python and TypeScript)
by [Alex Dan]