13.11. How to Configure AWS Lambda: Testing Lambda Functions

The AWS Lambda function is a crucial part of the AWS ecosystem that allows developers to run code without having to manage servers. This code runs in response to events, such as changes to data in an Amazon S3 bucket or Amazon DynamoDB table, HTTP requests from Amazon API Gateway, etc. In this chapter, we will discuss how to configure AWS Lambda and how to test Lambda functions.

Setting up AWS Lambda

To configure AWS Lambda, you need to follow the steps below:

1. Go to the AWS console and click on 'Services'.
2. In the 'Compute' section, click on 'Lambda'.
3. Click 'Create role'.
4. Choose 'Author from Scratch' and give your role a name.
5. Select 'Python 3.8' as your runtime environment.
6. Under 'Lambda function', click 'Create new function'.
7. On the next screen, you need to provide details about the function such as function name, description, timeout, etc.
8. After filling in the details, click on 'Create role'.

Congratulations, you have successfully created a Lambda function. Now, let's discuss how to test Lambda functions.

Testing Lambda functions

After you create a Lambda function, it's important to test it to ensure it's working as expected. AWS provides an easy way to test Lambda functions. Here are the steps to test a Lambda function:

1. In the AWS Lambda console, choose the function you want to test.
2. Click 'Select an event test' in the 'Configured event test' drop-down menu.
3. Click 'Create new event test'.
4. In the dialog box, enter a name for the test event.
5. Enter a JSON event body that matches the input structure of your function's handler.
6. Click 'Create'.
7. To test the function, choose 'Test'.

After you click 'Test', AWS Lambda runs your function using the test event you specified. AWS Lambda displays test results, including logs and trace information.

An important thing to note is that if your function accesses other AWS resources or calls other Lambda functions, these actions will be performed during testing. Therefore, ensure that your role is configured correctly and that you have appropriate permissions to access other AWS resources.

Additionally, if you are using AWS API Gateway in conjunction with AWS Lambda, you can test your Lambda function directly from the API Gateway console. Simply select your API, choose the method your Lambda function is using, and click 'Test'. You can provide a request body and query parameters, and API Gateway will display the response from your Lambda function.

In summary, AWS Lambda is a powerful tool for developing and running code without the need to manage servers. With the ability to test Lambda functions directly from the AWS console, developers can ensure their functions are working correctly before putting them into production.