API Gateway -> Lambda -> Comprehend

This patterns shows CDK deployment on how to leverage Amazon API Gateway, AWS Lambda, and Amazon Comprehend to perform Sentiment Analysis in a serverless fashion.

Architecture

What resources will be created?

This CDK code will create the following:

• 1 API Gateway with HTTP Endpoint
• 1 Lambda (to invoke the Comprehend API)
• 1 IAM role (for the Lambda to invoke Comprehend)

Requirements

Development Environment

Cloud 9

This code for this pattern is executed in AWS Cloud9 environment. The EC2 instance used is m5.large (8 GiB RAM + 2 vCPU).

AWS setup

Region

If you have not yet run aws configure and set a default region, you must do so, or you can also run export AWS_DEFAULT_REGION=<your-region>. The region used in the demonstration is us-east-1 as Bedrock service is available only in limited regions.

Authorization

You must use a role that has sufficient permissions to create Iam roles, as well as cloudformation resources

Python >=3.8

Make sure you have python3 installed at a version >=3.8.x in the CDK environment. The demonstration has used python version 3.10.

AWS CDK

Make sure you have the AWS CDK installed in the Cloud9 environment.

Setup

Set up environment and gather packages

cd apigw-lambda-comprehend-cdk-python

Install the required dependencies (aws-cdk-lib and constructs) into your Python environment

pip install -r requirements.txt

Gather and deploy resources with the CDK

First synthesize, which executes the application, defines which resources will be created, and translates this into a cloudformation template

cdk synth

Now bootstrap, which provisions the resources you'll use when deploying the application

cdk bootstrap

and deploy with

cdk deploy

The deployment will create a Lex bot, a Lambda and a S3 bucket.

How it works

The API Gateway handles the incoming requests from user and it invokes the relevant route. The Lambda, triggered by API Gateway, invokes the Comprehend's DetectSentiment API and the analyzed response from Comprehend service is routed back to the requester.

Testing

Upon successful deployment of the stack, the Output section would provide the APIEndpoint in the CDK environment. Alternatively, the APIEndpoint can be found from the Outputs section of the CloudFormation stack.

Use the below format to the test the API (replace the API Endpoint with the one retrieved from the above step):

curl -d '{"input": "I love AWS Services."}' -H 'Content-Type: application/json' https://<abcdefg>.execute-api.<region>.amazonaws.com/DetectSentiment

A response as below would be seen on the terminal console:

{
    "Sentiment": "POSITIVE",
    "Confidence Score": {
        "Positive": 0.9994897842407227,
        "Negative": 0.0000562662971788086,
        "Neutral": 0.00038276115083135664,
        "Mixed": 0.00007121496309991926
    }
}

Cleanup

To clean up the resources created as part of this demonstration, run the command cdk destroy in the directory apigw-lambda-comprehend-cdk-python.