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Invoke a Lambda function using an AWS SDK

The following code examples show how to invoke a Lambda function.

Note
The source code for these examples is in the AWS Code Examples GitHub repository. Have feedback on a code example? Create an Issue in the code examples repo.

[ Java ]

SDK for Java 2.x
To learn how to set up and run this example, see GitHub.

    public static void invokeFunction(LambdaClient awsLambda, String functionName) {

        InvokeResponse res = null ;
        try {
            // Need a SdkBytes instance for the payload.
            JSONObject jsonObj = new JSONObject();
            jsonObj.put("inputValue", "2000");
            String json = jsonObj.toString();
            SdkBytes payload = SdkBytes.fromUtf8String(json) ;

            // Setup an InvokeRequest.
            InvokeRequest request = InvokeRequest.builder()
                .functionName(functionName)
                .payload(payload)
                .build();

            res = awsLambda.invoke(request);
            String value = res.payload().asUtf8String() ;
            System.out.println(value);

        } catch(LambdaException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
    }
  • For API details, see Invoke in AWS SDK for Java 2.x API Reference.

[ Kotlin ]

SDK for Kotlin
This is prerelease documentation for a feature in preview release. It is subject to change. To learn how to set up and run this example, see GitHub.

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}")
    }
}
  • For API details, see Invoke in AWS SDK for Kotlin API reference.

[ Python ]

SDK for Python (Boto3)
To learn how to set up and run this example, see GitHub.

class LambdaWrapper:
    def __init__(self, lambda_client, iam_resource):
        self.lambda_client = lambda_client
        self.iam_resource = iam_resource

    def invoke_function(self, function_name, function_params, get_log=False):
        """
        Invokes a Lambda function.

        :param function_name: The name of the function to invoke.
        :param function_params: The parameters of the function as a dict. This dict
                                is serialized to JSON before it is sent to Lambda.
        :param get_log: When true, the last 4 KB of the execution log are included in
                        the response.
        :return: The response from the function invocation.
        """
        try:
            response = self.lambda_client.invoke(
                FunctionName=function_name,
                Payload=json.dumps(function_params),
                LogType='Tail' if get_log else 'None')
            logger.info("Invoked function %s.", function_name)
        except ClientError:
            logger.exception("Couldn't invoke function %s.", function_name)
            raise
        return response
  • For API details, see Invoke in AWS SDK for Python (Boto3) API Reference.

For a complete list of AWS SDK developer guides and code examples, see Using Lambda with an AWS SDK. This topic also includes information about getting started and details about previous SDK versions.