lab02-dynamodb

Lab 02: Invoke Lambda function with DynamoDB access

This lab uses the Serverless Framework!

Goal

Create a simple API Gateway that invokes a Lambda function on an HTTP GET request that fetches data from DynamoDB.

Instructions

First, create a new Serverless Framework project. Replace $user with your name (e.g. andreas). The command will create a simple project with a Lambda function written in TypeScript.

serverless create --template aws-nodejs-typescript --path dynamodb-$user

Change into the newly created directory and install the necessary dependencies.

cd dynamodb-$user
npm i

In the serverless.yml file, set the region to the AWS region of your choice.

Add the DynamoDB table to serverless.yml

Remember that the Serverless Framework uses CloudFormation to deploy AWS resources. You can add CloudFormation resources to the resources section in serverless.yml.

Add a simple DynamoDB table to store items and pick a unique table name.

Deploy your changes.

Add permissions

By default, the Lambda function is not allowed to access the newly created DynamoDB table. Add permissions to allow the function to run dynamodb:Scan operations against the newly created table. You can define them in the provider section of the serverless.yml file.

Deploy your changes.

Pass table name to function

Pass the DynamoDB table name to the Lambda function using the environment variable TABLE_NAME. You can define environment variables in the provider section of the serverless.yml file.

Deploy your changes.

Scan DynamoDB on GET request

Add the aws-sdk as a dependency.

In handler.ts, instantiate a DynamoDB client with...

import { DynamoDB } from 'aws-sdk';
const dynamoDb = new DynamoDB.DocumentClient();

...and scan the newly created table.

Return the array of items.

Deploy your changes and test the API. An empty array should be returned.

Now add some items to the table using the AWS Management Console and invoke the API again.

Finally, remove the stack.

serverless remove

Help

• Serverless Framework config file reference for AWS
• Serverless Framework variables
• CloudFormation Resource AWS::DynamoDB::Table
• AWS SDK DynamoDB.DocumentClient