AWS Serverless Architecture: API Gateway, Lambda, and DynamoDB
Introduction
Serverless architecture on AWS enables developers to build scalable applications without provisioning or managing servers. Instead of worrying about infrastructure, we focus purely on business logic while AWS handles scaling, availability, and execution behind the scenes.
In this hands-on practice, I implemented a complete serverless workflow using AWS Lambda, Amazon API Gateway, and Amazon DynamoDB to understand how these services integrate in real-world scenarios.
Why Serverless Architecture?
Serverless architecture is increasingly popular due to the following advantages:
No need to provision or manage servers
Pay only for execution time (no idle cost)
Automatic scaling and high availability
Faster development and deployment
Although the term serverless is used, servers still exist—they are fully managed by AWS and abstracted from the user.
AWS Services Used
Amazon API Gateway – Acts as an HTTP entry point to trigger backend services
AWS Lambda – Executes code in response to events
Amazon DynamoDB – Fully serverless NoSQL database
Amazon CloudWatch – Monitoring and logging for Lambda executions
Architecture Overview
Client / API Request
→ API Gateway (GET / POST)
→ Lambda Function
→ DynamoDB Table
This architecture follows a fully serverless and event-driven design.
Step 1: Understanding API Gateway
API Gateway is commonly used to expose backend services using HTTP methods such as GET, POST, PUT, and DELETE.
Key concepts used:
REST API – Used for request-response based applications
Resources – Logical paths (similar to subdomains)
Methods – HTTP operations like GET and POST
Stages – Environment separation such as dev, test, and prod
Step 2: Create a Sample Lambda Function
A simple Lambda function was created using Python to understand:
Lambda handler
Input event
Execution context
Response handling
This Lambda function serves as the backend logic invoked by API Gateway.
Step 3: Integrate API Gateway with Lambda (GET Method)
A REST API was created in API Gateway and integrated with the Lambda function using a GET method.
Steps performed:
Created a REST API (Regional)
Added a resource under
/Configured GET method
Integrated it with Lambda
Tested the invocation directly from API Gateway
Deployed the API to a stage
Concept used:
API Gateway acts as a trigger for Lambda, enabling external access via an invocation URL.
Step 4: Introduction to DynamoDB
DynamoDB is a fully managed, serverless NoSQL database provided by AWS.
Key characteristics:
Key-value based storage
Dynamic schema (schema-less)
High performance with partition keys
Supports ACID transactions
Integrates easily with Lambda
Step 5: Create DynamoDB Table and Insert Data
A DynamoDB table was created with:
Table name
Primary key (partition key)
Sample records were inserted directly using the console to understand how items are stored and queried.
Concept used:
Primary key plays a critical role in performance and data access patterns.
Step 6: Use Lambda to Read Data from DynamoDB
Lambda was updated to interact with DynamoDB using Boto3.
The function scans the table and returns records as a response.
Concepts used:
AWS SDK (Boto3)
Lambda execution role permissions
DynamoDB scan operation
Step 7: Insert Data into DynamoDB Using API Gateway (POST Method)
To simulate real-world data ingestion:
A POST method was created in API Gateway
Request body (JSON) was passed to Lambda
Lambda inserted the received data into DynamoDB
Concept used:
API request body is passed as the event object to Lambda
Lambda uses that event to perform database operations
During Manual Test:
Step 8: External API Testing Using Postman
Instead of using API Gateway’s built-in test option, the deployed API endpoint was tested using Postman.
Steps performed:
Selected POST method
Used invocation URL
Passed JSON data in request body
Validated record insertion in DynamoDB
Verified Lambda execution in CloudWatch logs
After External Test using POSTMAN:
Monitoring and Validation
All Lambda executions were monitored using Amazon CloudWatch Logs, which helped validate:
API Gateway invocation
Lambda execution flow
DynamoDB interactions
Conclusion
This hands-on practice helped me understand how AWS serverless services work together to build scalable, event-driven applications. By combining API Gateway, Lambda, and DynamoDB, it is possible to design robust backend systems without managing infrastructure.
Key takeaways:
Strong understanding of Lambda handler, event, and context
Practical API Gateway integration
Real-time data insertion and retrieval using DynamoDB
End-to-end serverless workflow validation
This exercise reinforced the power and simplicity of serverless architecture on AWS.
