Get started with the SDK for Kotlin - AWS SDK for Kotlin
Step 1: Set up for this tutorialStep 2: Create the projectStep 3: Write the codeStep 4: Build and run the applicationNext steps

Get started with the SDK for Kotlin

The AWS SDK for Kotlin provides Kotlin APIs for each AWS service. Using the SDK, you can build Kotlin applications that work with Amazon S3, Amazon EC2, Amazon DynamoDB, and more.

This tutorial shows you how to use Gradle to define dependencies for the AWS SDK for Kotlin. Then, you create code that writes data to a DynamoDB table. Although you might want to use the features of an IDE, all you need for this tutorial is a terminal window and a text editor.

Follow these steps to complete this tutorial:

Step 1: Set up for this tutorial

Before you begin this tutorial, you need an IAM Identity Center permission set that can access DynamoDB and a Kotlin development environment configured with IAM Identity Center single sign-on settings to access to AWS.

Follow the instructions in the Basic set up of this guide to get the basics setup for this tutorial.

After you have configured your development environment with single sign-on access for the Kotlin SDK and you have an active AWS access portal session, continue with Step 2.

Step 2: Create the project

To create the project for this tutorial, first use Gradle to create a Kotlin project. Then, update the gradle.build.kts file with the required settings and dependencies for the AWS SDK for Kotlin.

To create a new project using Gradle

Note

Gradle version 8.1 offers the four prompts in step 3 below. If you use a different version of Gradle the prompts might differ.

  1. Create a new directory called getstarted in a location of your choice, such as your desktop or home folder.

  2. Open a terminal or command prompt window and navigate to the getstarted directory you created.

  3. Use the following command to create a new Gradle project configuration file (build.gradle.kts) and a basic Kotlin class.

    gradle init --type kotlin-application --dsl kotlin

    • When prompted with Project name, press Enter.

    • When prompted for Source package, enter example.aws.getstarted.

    • When prompted with Enter target version of Java (min. 7) (default: 11), press Enter.

    • When prompted with Generate build using new APIs and behavior, press the Enter key.

To configure your project with dependencies for the AWS SDK for Kotlin and Amazon S3

  • In the folder getstarted that you created in the previous procedure, navigiate to the app directory and open the build.gradle.kts file.

  • Replace its contents with the following Gradle code, and then save your changes.

    import org.jetbrains.kotlin.gradle.tasks.KotlinCompile

plugins {
    kotlin("jvm") version "1.9.10"
    application
}

group = "example.aws"
version = "1.0-SNAPSHOT"

repositories {
    mavenCentral()
}

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

tasks.withType<Test> {
    useJUnitPlatform()
}

tasks.withType<KotlinCompile>() {
    kotlinOptions.jvmTarget = "17"
}

application.mainClass.set("example.aws.getstarted.AppKt")

    The dependencies section contains an entry for the Amazon S3 module of the AWS SDK for Kotlin. The Gradle compiler is configured to use Java 17 in the tasks.withType<KotlinCompile>() section.

    Note

    For the latest version of the Amazon S3 module of the SDK for Kotlin, see the Maven central repository and use that value in the following code.

Step 3: Write the code

After the project has been created and configured, edit the project’s default class App to use the following example code.

  1. In your project folder app, navigate to the directory src/main/kotlin/example/aws/getstarted. Open the App.kt file.

  2. Replace its contents with the following code and save the file.

    package example.aws.getstarted

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

val REGION = "us-west-2"
val BUCKET = "bucket-${UUID.randomUUID()}"
val KEY = "key"

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

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

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

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

            cleanUp(s3)
        }
}

suspend fun setupTutorial(s3: S3Client) {
    println("Creating bucket $BUCKET...")
    s3.createBucket {
        bucket = BUCKET
        if (REGION != "us-east-1") { // Do not set location constraint for us-east-1.
            createBucketConfiguration {
                locationConstraint = BucketLocationConstraint.fromValue(REGION)
            }
        }
    }
    println("Bucket $BUCKET created successfully!")
}

suspend fun cleanUp(s3: S3Client) {
    println("Deleting object $BUCKET/$KEY...")
    s3.deleteObject {
        bucket = BUCKET
        key = KEY
    }
    println("Object $BUCKET/$KEY deleted successfully!")

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

Step 4: Build and run the application

After the project is created and contains the example class, build and run the application.

  1. Open a terminal or command prompt window and navigate to your project directory getstarted.

  2. Use the following command to build and run your application:

    gradle run

The application calls the createBucket API operation to create a new S3 bucket and then calls putObject to put a new object into the new S3 bucket.

In the cleanUp() function at the end, the application deletes the object and then deletes the S3 bucket.

To see the results in the Amazon S3 console

  1. In App.kt, comment out the line cleanUp(s3) in the runBlocking section and save the file.

  2. Rebuild the project and put a new object into a new S3 bucket by running gradle run.

  3. Sign in to the Amazon S3 console to view the new object in the new S3 bucket.

After you view the object, delete the S3 bucket.

Success

If your Gradle project built and ran without error, then congratulations. You have successfully built your first Kotlin application using the AWS SDK for Kotlin.

Cleanup

When you are done developing your new application, delete any AWS resources that you created during this tutorial to avoid incurring any charges. You might also want to delete or archive the project folder (get-started) that you created in Step 2.

Follow these steps to clean up resources:

  • If you commented out the call to the cleanUp() function, delete the S3 bucket by using the Amazon S3 console.

Next steps

Now that you have the basics down, you can learn about the following: