Serverless CRUD Application using AWS Lambda, API Gateway & DynamoDB

This project demonstrates how to build a fully serverless, scalable, and pay-per-use CRUD REST API using AWS Lambda, Amazon API Gateway, and Amazon DynamoDB.
It supports Create, Read, Update, and Delete operations, all triggered through API endpoints.

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Tech Stack

• AWS Lambda – Serverless compute for executing backend logic.
• Amazon API Gateway – To expose RESTful API endpoints.
• Amazon DynamoDB – NoSQL database for storing data.
• AWS IAM – To manage secure permissions for Lambda.
• Amazon CloudWatch – For logging and monitoring.
• Amazon SNS – For alert notifications.

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Project Architecture Overview

High-Level Flow:

Client (Postman / Browser)
   ↓
API Gateway (REST Endpoints)
   ↓
AWS Lambda (CRUD Functions)
   ↓
DynamoDB (ItemsTable)
   ↓
CloudWatch (Logs & Metrics)

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Step-by-Step Workflow

Below is the exact workflow I followed to build this project from scratch:

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1️) Create the DynamoDB Table

• Go to AWS Console → DynamoDB → Create Table
• Table name: ItemsTable
• Partition key: id (String)
• Keep other settings as default (On-Demand capacity)
• Click Create Table

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Result:- DynamoDB table ready to store items.

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2️) Create IAM Role for Lambda

• Go to IAM → Roles → Create Role
• Trusted entity type: AWS Service
• Use case: Lambda
• Attach policies:
  • AmazonDynamoDBFullAccess
  • CloudWatchFullAccess
• Name the role: LambdaDynamoDBRole
• Click Create Role

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Result:- A secure role with DynamoDB & CloudWatch permissions created.

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3️) Create Lambda Functions

We created 4 Lambda functions, one for each CRUD operation.

Function Name	Purpose	Operation
CreateItemFunction	Adds a new item to DynamoDB	POST /items
GetItemsFunction	Retrieves all items	GET /items
UpdateItemFunction	Updates an existing item	PUT /items/{id}
DeleteItemFunction	Deletes an item by ID	DELETE /items/{id}

Each Lambda uses Python (boto3) to interact with DynamoDB.

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Result:- All Lambda functions tested successfully inside AWS Lambda Console.

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4️) Connect API Gateway to Lambda

• Go to API Gateway → Create API → REST API
• Create a new Resource named /items
• Under /items, create the following Methods:
  • POST → Integrate with CreateItemFunction
  • GET → Integrate with GetItemsFunction
• Create another resource /items/{id}
  • PUT → Integrate with UpdateItemFunction
  • DELETE → Integrate with DeleteItemFunction
• Enable Lambda Proxy Integration for all.

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Result: API Gateway connected with all Lambda functions.

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5️) Deploy the API

• Go to Actions → Deploy API

• Create a new stage named prod

• Copy the Invoke URL, e.g.:

  https://<api-id>.execute-api.<region>.amazonaws.com/prod
  

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Result: Public API endpoints are now live and callable from Postman.

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6️) Test Using Postman

Use the following endpoints:

Method	Endpoint	Description	Example Body
POST	/items	Create an item	{ "name": "Test Item", "description": "Created via Postman" }
GET	/items	Read all items	—
PUT	/items/{id}	Update an item	{ "name": "Updated Item", "description": "Modified" }
DELETE	/items/{id}	Delete an item	—

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Result: All CRUD operations returned correct responses and updated DynamoDB successfully.

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Step 7: Add Monitoring & Alerts using CloudWatch and SNS

Monitoring and alerting are crucial for production-grade systems. Below are the exact steps I followed to enable logging, monitoring, and alert notifications for my Lambda functions.

PART 1 — Enable and View CloudWatch Logs for Lambda

Every Lambda automatically sends logs to CloudWatch, but let’s confirm and check them.

Steps:

1. Go to AWS Console → Lambda → your function (e.g., CreateItemFunction)
2. Scroll down to Monitor → View logs in CloudWatch
3. You’ll see a log group like:

   /aws/lambda/CreateItemFunction
   

4. Inside this log group, you can open individual Log Streams to view:
   • Start and end time of Lambda invocation
   • Any print() or console.log() outputs
   • Error messages if Lambda failed

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Result:
Lambda is already logging to CloudWatch automatically.
Now let’s turn those logs into alerts.

PART 2 — Create a CloudWatch Alarm + SNS Email Alert

This will send me an email when Lambda fails (e.g., due to an exception or timeout).

Create an SNS Topic

1. Go to AWS Console → SNS → Topics → Create Topic
2. Choose Standard type
3. Name it something like:

   LambdaErrorAlerts
   

4. Click Create topic

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Subscribe to the Topic

1. After creating the topic → Click on it → Create Subscription
2. Protocol → Email
3. Endpoint → Enter your email address (the one you want alerts on)
4. Check your inbox and click Confirm subscription

Once confirmed, the status will show as Confirmed in the SNS dashboard.

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Create a CloudWatch Alarm for Lambda

1. Go to AWS Console → CloudWatch → Alarms → All Alarms → Create alarm
2. Choose Select metric
3. Choose:

   Lambda Metrics → By Function Name → <YourFunctionName> → Errors
   

4. Click Select metric
5. Under Conditions, set:
   • Threshold type → Static
   • Whenever Errors is ≥ 1 for 1 datapoint
6. Under Actions → Alarm state trigger → In Alarm, select:
   • Send a notification to → LambdaErrorAlerts
7. Give it a name:

   LambdaErrorAlarm-CreateItemFunction
   

8. Click Create Alarm

We can repeat this for your other functions too(Get, Update, Delete).

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Final Result:
The system now automatically sends email alerts whenever any Lambda function fails.

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Project Highlights

• 100% Serverless (no servers or EC2 required)
• Pay-per-use pricing
• Scalable CRUD API
• Clean IAM-based security
• Tested with Postman
• Observable with CloudWatch

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Learnings & Key Takeaways

• Gained hands-on experience with AWS Lambda and API Gateway integration
• Learned to manage IAM roles & permissions effectively
• Understood DynamoDB CRUD operations using boto3
• Practiced API testing with Postman
• Created a scalable, production-ready serverless system

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