Lambda examples using SDK for Kotlin

suspend fun main(args: Array<String>) {
    val usage = """
        Usage:
            <functionName> <role> <handler> <bucketName> <updatedBucketName> <key> 

        Where:
            functionName - The name of the AWS Lambda function. 
            role - The AWS Identity and Access Management (IAM) service role that has AWS Lambda permissions. 
            handler - The fully qualified method name (for example, example.Handler::handleRequest). 
            bucketName - The Amazon Simple Storage Service (Amazon S3) bucket name that contains the ZIP or JAR used for the Lambda function's code.
            updatedBucketName - The Amazon S3 bucket name that contains the .zip or .jar used to update the Lambda function's code. 
            key - The Amazon S3 key name that represents the .zip or .jar file (for example, LambdaHello-1.0-SNAPSHOT.jar).
            """

    if (args.size != 6) {
        println(usage)
        exitProcess(1)
    }

    val functionName = args[0]
    val role = args[1]
    val handler = args[2]
    val bucketName = args[3]
    val updatedBucketName = args[4]
    val key = args[5]

    println("Creating a Lambda function named $functionName.")
    val funArn = createScFunction(functionName, bucketName, key, handler, role)
    println("The AWS Lambda ARN is $funArn")

    // Get a specific Lambda function.
    println("Getting the $functionName AWS Lambda function.")
    getFunction(functionName)

    // List the Lambda functions.
    println("Listing all AWS Lambda functions.")
    listFunctionsSc()

    // Invoke the Lambda function.
    println("*** Invoke the Lambda function.")
    invokeFunctionSc(functionName)

    // Update the AWS Lambda function code.
    println("*** Update the Lambda function code.")
    updateFunctionCode(functionName, updatedBucketName, key)

    // println("*** Invoke the function again after updating the code.")
    invokeFunctionSc(functionName)

    // Update the AWS Lambda function configuration.
    println("Update the run time of the function.")
    updateFunctionConfiguration(functionName, handler)

    // Delete the AWS Lambda function.
    println("Delete the AWS Lambda function.")
    delFunction(functionName)
}

suspend fun createScFunction(
    myFunctionName: String,
    s3BucketName: String,
    myS3Key: String,
    myHandler: String,
    myRole: String,
): String {
    val functionCode =
        FunctionCode {
            s3Bucket = s3BucketName
            s3Key = myS3Key
        }

    val request =
        CreateFunctionRequest {
            functionName = myFunctionName
            code = functionCode
            description = "Created by the Lambda Kotlin API"
            handler = myHandler
            role = myRole
            runtime = Runtime.Java8
        }

    // Create a Lambda function using a waiter
    LambdaClient { region = "us-west-2" }.use { awsLambda ->
        val functionResponse = awsLambda.createFunction(request)
        awsLambda.waitUntilFunctionActive {
            functionName = myFunctionName
        }
        return functionResponse.functionArn.toString()
    }
}

suspend fun getFunction(functionNameVal: String) {
    val functionRequest =
        GetFunctionRequest {
            functionName = functionNameVal
        }

    LambdaClient { region = "us-west-2" }.use { awsLambda ->
        val response = awsLambda.getFunction(functionRequest)
        println("The runtime of this Lambda function is ${response.configuration?.runtime}")
    }
}

suspend fun listFunctionsSc() {
    val request =
        ListFunctionsRequest {
            maxItems = 10
        }

    LambdaClient { region = "us-west-2" }.use { awsLambda ->
        val response = awsLambda.listFunctions(request)
        response.functions?.forEach { function ->
            println("The function name is ${function.functionName}")
        }
    }
}

suspend fun invokeFunctionSc(functionNameVal: String) {
    val json = """{"inputValue":"1000"}"""
    val byteArray = json.trimIndent().encodeToByteArray()
    val request =
        InvokeRequest {
            functionName = functionNameVal
            payload = byteArray
            logType = LogType.Tail
        }

    LambdaClient { region = "us-west-2" }.use { awsLambda ->
        val res = awsLambda.invoke(request)
        println("The function payload is ${res.payload?.toString(Charsets.UTF_8)}")
    }
}

suspend fun updateFunctionCode(
    functionNameVal: String?,
    bucketName: String?,
    key: String?,
) {
    val functionCodeRequest =
        UpdateFunctionCodeRequest {
            functionName = functionNameVal
            publish = true
            s3Bucket = bucketName
            s3Key = key
        }

    LambdaClient { region = "us-west-2" }.use { awsLambda ->
        val response = awsLambda.updateFunctionCode(functionCodeRequest)
        awsLambda.waitUntilFunctionUpdated {
            functionName = functionNameVal
        }
        println("The last modified value is " + response.lastModified)
    }
}

suspend fun updateFunctionConfiguration(
    functionNameVal: String?,
    handlerVal: String?,
) {
    val configurationRequest =
        UpdateFunctionConfigurationRequest {
            functionName = functionNameVal
            handler = handlerVal
            runtime = Runtime.Java11
        }

    LambdaClient { region = "us-west-2" }.use { awsLambda ->
        awsLambda.updateFunctionConfiguration(configurationRequest)
    }
}

suspend fun delFunction(myFunctionName: String) {
    val request =
        DeleteFunctionRequest {
            functionName = myFunctionName
        }

    LambdaClient { region = "us-west-2" }.use { awsLambda ->
        awsLambda.deleteFunction(request)
        println("$myFunctionName was deleted")
    }
}

suspend fun createNewFunction(
    myFunctionName: String,
    s3BucketName: String,
    myS3Key: String,
    myHandler: String,
    myRole: String,
): String? {
    val functionCode =
        FunctionCode {
            s3Bucket = s3BucketName
            s3Key = myS3Key
        }

    val request =
        CreateFunctionRequest {
            functionName = myFunctionName
            code = functionCode
            description = "Created by the Lambda Kotlin API"
            handler = myHandler
            role = myRole
            runtime = Runtime.Java8
        }

    LambdaClient { region = "us-west-2" }.use { awsLambda ->
        val functionResponse = awsLambda.createFunction(request)
        awsLambda.waitUntilFunctionActive {
            functionName = myFunctionName
        }
        return functionResponse.functionArn
    }
}

suspend fun delLambdaFunction(myFunctionName: String) {
    val request =
        DeleteFunctionRequest {
            functionName = myFunctionName
        }

    LambdaClient { region = "us-west-2" }.use { awsLambda ->
        awsLambda.deleteFunction(request)
        println("$myFunctionName was deleted")
    }
}

suspend fun invokeFunction(functionNameVal: String) {
    val json = """{"inputValue":"1000"}"""
    val byteArray = json.trimIndent().encodeToByteArray()
    val request =
        InvokeRequest {
            functionName = functionNameVal
            logType = LogType.Tail
            payload = byteArray
        }

    LambdaClient { region = "us-west-2" }.use { awsLambda ->
        val res = awsLambda.invoke(request)
        println("${res.payload?.toString(Charsets.UTF_8)}")
        println("The log result is ${res.logResult}")
    }
}

Shows how to develop a photo asset management application that detects labels in images using Amazon Rekognition and stores them for later retrieval.

For complete source code and instructions on how to set up and run, see the full example on GitHub.

For a deep dive into the origin of this example see the post on AWS Community.