AWS SDK with Kotlin

Boy was I happy when I read the news about the general availability of the AWS SDK for Kotlin. Finally, time to use Kotlin for my infrastructure as code projects.

https://aws.amazon.com/about-aws/whats-new/2023/11/aws-sdk-kotlin/

In this tutorial I will follow Amazons tutorial on how to create an S3 bucket, create an object from a ByteStream in the S3 Bucket and then clean up everything again by using the AWS SDK in Kotlin. I had to make some changes to the existing tutorial to make it work in my development environment. All-in-all, it was all straight-forward.

Here is the general website on the AWS SDK for Kotlin: https://aws.amazon.com/sdk-for-kotlin/

Under this website, you can find the tutorial I am following in this blog post: https://docs.aws.amazon.com/sdk-for-kotlin/latest/developer-guide/get-started.html

First, we need to create a Gradle project. I just kept everything at the default settings.

% mkdir aws-cdk-kotlin
% cd aws-cdk-kotlin
% gradle init --type kotlin-application --dsl kotlin

Project name (default: aws-cdk-kotlin):

Source package (default: aws.cdk.kotlin):

Enter target version of Java (min. 7) (default: 21):

Generate build using new APIs and behavior (some features may change in the next minor release)? (default: no) [yes, no]

> Task :init
To learn more about Gradle by exploring our Samples at https://docs.gradle.org/8.5/samples/sample_building_kotlin_applications.html

BUILD SUCCESSFUL in 5s
2 actionable tasks: 2 executed
%

Then, we need to add the dependency for the AWS SDK.

in build.gradle.kts

...

dependencies {
	...
	implementation("aws.sdk.kotlin:s3:1.0.0")
}

Here is the code from the tutorial but slightly adapted to newer syntax

import aws.sdk.kotlin.services.s3.S3Client
import aws.sdk.kotlin.services.s3.model.*
import aws.smithy.kotlin.runtime.content.ByteStream
import kotlinx.coroutines.runBlocking
import java.util.*

val REGION = "eu-central-1"
val BUCKET = "bucket-${UUID.randomUUID()}"
val KEY = "my-s3-bucket-key"

fun main(): Unit = runBlocking {
	S3Client.fromEnvironment { region = REGION }.use { s3 ->
		setupTutorial(s3)

		println("Creating object $BUCKET/$KEY...")

		val putObjectRequest = PutObjectRequest {
			bucket = BUCKET
			key = KEY
			body = ByteStream.fromString("Testing with the Kotlin SDK")
		}
		s3.putObject(putObjectRequest)

		println("Object $BUCKET/$KEY created successfully!")
		cleanUp(s3)
	}
}

suspend fun setupTutorial(s3: S3Client) {
	println("Creating bucket $BUCKET...")
	val createBucketRequest = CreateBucketRequest {
		bucket = BUCKET
		createBucketConfiguration {
			locationConstraint = BucketLocationConstraint.fromValue(REGION)
		}
	}
	s3.createBucket(createBucketRequest)
	println("Bucket $BUCKET created successfully!")
}

suspend fun cleanUp(s3: S3Client) {
	println("Deleting object $BUCKET/$KEY...")
	val deleteObjectRequest = DeleteObjectRequest {
		bucket = BUCKET
		key = KEY
	}
    s3.deleteObject(deleteObjectRequest)

    println("Object $BUCKET/$KEY deleted successfully!")

    println("Deleting bucket $BUCKET...")
    val deleteBucketRequest = DeleteBucketRequest {
        bucket = BUCKET
    }
    s3.deleteBucket(deleteBucketRequest)
    println("Bucket $BUCKET deleted successfully!")
}

Let my friend ChatGPT explain you what the code does:

Imports: The code begins by importing necessary classes from the AWS SDK for Kotlin, which includes S3 client classes and models. It also imports ByteStream for handling data streams and runBlocking for coroutine support.
Constants:
- REGION: Specifies the AWS region (e.g., “eu-central-1”).
- BUCKET: A unique bucket name is generated using UUID.randomUUID().
- KEY: Defines the key name for the object to be stored in S3.
Main Function:
- Initializes an S3 client with the specified region.
- Calls setupTutorial to create a new S3 bucket.
- Creates a text object in the bucket with the specified key.
- Cleans up by deleting the created object and bucket.
setupTutorial Function:
- Creates an S3 bucket in the specified region.
- Uses CreateBucketRequest to configure and create the bucket.
cleanUp Function:
- Deletes the previously created object and bucket.
- Uses DeleteObjectRequest and DeleteBucketRequest for deletion tasks.
Coroutine Usage: The runBlocking coroutine builder is used to execute suspend functions (setupTutorial and cleanUp) in the main function. This is necessary as AWS SDK calls are suspending functions, requiring a coroutine context.

Thank you, ChatGPT.

Finally, we run the code and receive the output as expected.

Creating bucket bucket-bad30829-1f4f-432a-acf3-fccafac14ecf...
Bucket bucket-bad30829-1f4f-432a-acf3-fccafac14ecf created successfully!
Creating object bucket-bad30829-1f4f-432a-acf3-fccafac14ecf/my-s3-bucket-key...
Object bucket-bad30829-1f4f-432a-acf3-fccafac14ecf/my-s3-bucket-key created successfully!
Deleting object bucket-bad30829-1f4f-432a-acf3-fccafac14ecf/my-s3-bucket-key...
Object bucket-bad30829-1f4f-432a-acf3-fccafac14ecf/my-s3-bucket-key deleted successfully!
Deleting bucket bucket-bad30829-1f4f-432a-acf3-fccafac14ecf...
Bucket bucket-bad30829-1f4f-432a-acf3-fccafac14ecf deleted successfully!

That was easy!

If you have any further questions, need specific code examples, or require additional assistance, please don’t hesitate to leave a comment or send me a message.

Thank you for reading!