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README.md

Powertools for AWS Lambda (TypeScript) examples in CDK

This is a deployable CDK app that deploys AWS Lambda functions as part of a CloudFormation stack. These Lambda functions use the utilities made available as part of Powertools for AWS Lambda (TypeScript) to demonstrate their usage.

Warning

You will need to have a valid AWS Account in order to deploy these resources. Many of the services in the example are covered AWS Free Tier but you may incur charges if you exceed the free tier limits. If you don't have an AWS Account follow these instructions to create one.

The example functions, located in the functions folder, are frontend by a REST API that is deployed using AWS API Gateway.

The API has three endpoints:

  • POST / - Adds an item to the DynamoDB table
  • GET / - Retrieves all items from the DynamoDB table
  • GET /{id} - Retrieves a specific item from the DynamoDB table

Deploying the stack

Note

The examples/app directory where this example is located is part of a monorepo. If you are interested in deploying the example only, follow the instructions below. If instead you are working on the monorepo and want to deploy the example, follow the instructions in the CONTRIBUTING doc, then run npm run cdk deploy -w examples/app from the project's root.

If this is the first time you're using CDK in your AWS Account & AWS Region, you may need to run npm run cdk bootstrap aws://<YOU_AWS_ACCOUNT_ID>/<AWS_REGION> --profile <YOUR_AWS_PROFILE> to bootstrap your account for CDK.

Then, still from within the examples/app directory, run the following commands:

  • npm i --prefix ./ to install the dependencies
  • npm run cdk deploy and follow the prompts to deploy the stack

When the deployment is complete, you will see the output values that include the API Gateway Endpoint URL.

Execute the functions via API Gateway

Use the API Gateway Endpoint URL from the output values to execute the functions. First, let's add two items to the DynamoDB Table by running:

curl -XPOST --header 'Content-Type: application/json' --data '{"id":"myfirstitem","name":"Some Name for the first item"}' https://<api-id>.execute-api.eu-central-1.amazonaws.com/prod/
curl -XPOST --header 'Content-Type: application/json' --data '{"id":"myseconditem","name":"Some Name for the second item"}' https://<api-id>.execute-api.eu-central-1.amazonaws.com/prod/

Now, let's retrieve all items by running:

curl -XGET https://<api-id>.execute-api.eu-central-1.amazonaws.com/prod/

And finally, let's retrieve a specific item by running:

curl -XGET https://<api-id>.execute-api.eu-central-1.amazonaws.com/prod/myseconditem/

Observe the outputs in AWS CloudWatch & X-Ray

CloudWatch

If we check the logs in CloudWatch, we can see that the logs are structured like this

2022-04-26T17:00:23.808Z	e8a51294-6c6a-414c-9777-6b0f24d8739b	DEBUG	
{
    "level": "DEBUG",
    "message": "retrieved items: 0",
    "service": "getAllItems",
    "timestamp": "2022-04-26T17:00:23.808Z",
    "awsRequestId": "e8a51294-6c6a-414c-9777-6b0f24d8739b"
}

By having structured logs like this, we can easily search and analyse them in CloudWatch Logs Insight. Run the following query to get all messages for a specific awsRequestId:

filter awsRequestId="bcd50969-3a55-49b6-a997-91798b3f133a"
 | fields timestamp, message

AWS X-Ray

As we have enabled tracing for our Lambda-Funtions, you can visit AWS CloudWatch Console and see Traces and a Service Map for our application.

Cleanup

To delete the sample application that you created, run the command below while in the examples/cdk directory:

cdk destroy