Writing the foundation of a Lambda function

We can start our task with writing a Lambda function, which responds to S3 events and will resize the image. At this stage, the code will not resize the image, but it will only log the request, so first, we can see that the function is really triggered by S3.

As usual, we can create our new module with the name lambda-imageresizer:

$ mkdir -p lambda-imageresize/src/main/java/com/
      serverlessbook/lambda/imageresize

Then, let's add this new module to our settings.gradle file:

$ echo "include 'lambda-imageresizer'" >> settings.gradle

We can now create our Handler class in the com.serverlessbook.lambda.imageresize package:

$ touch lambda-imageresizer/src/main/java/com/serverlessbook/lambda/
      imageresizer/Handler.java

In this Lambda function, we will consume standardized events prepared by S3. AWS provides a Java package that includes POJOs for this type of event, including S3. This package can be found in the Maven repository by the name com...