Determine the AWS lambda name on runtime in Java

Question

I really like the approach of calling AWS lambdas from Java described in this blog post.
However, if I have 3 environments (int/test/live), and on each of them the lambda has a slightly different name (created via cloudformation), I can't think of a way to have one interface, and call lambda with a different name depending on the environment.
I am using Spring, and so if I could do something like:

@Component
interface MyLambdas {
    @Value("${name}")
    String name;

    @LambdaFunction(name = name)
    String callMyLambda(String stuff);
}

//and then
service = LambdaInvokerFactory.build(MyLambdas.class, lambda);

But obviously I can't do this on an interface, this won't be a bean! Is there any way at all to do this? I feel like I hit a brick wall...

Right now I am calling lambda "the old way":

String readLambdaName = "My_Lambda";

ObjectMapper objectMapper = new ObjectMapper();
AWSLambdaClient lambda = new AWSLambdaClient();
lambda.configureRegion(Regions.EU_WEST_1);

String json = objectMapper.writeValueAsString(request);
InvokeRequest req = new InvokeRequest()
        .withFunctionName(readLambdaName)
        .withPayload(json);

InvokeResult res = lambda.invoke(req);
int result = objectMapper.readTree(res.getPayload().array()).asInt();

Obviously with some exception handling here and there. This is not as nice of a solution tho...

For anyone following this, I have submitted an issue and a solution on aws-sdk github. hopefully something similar to my solution will make it to the next release of the SDK...

meeza · Accepted Answer · 2017-11-13 08:14:04Z

I resolved it by overriding the function name using "lambdaFunctionNameResolver".

//my lambda interface
public interface MyLambdaService {
    @LambdaFunction
    ApiGatewayProxyResponse execute(ApiGatewayRequest bit);
}

this is how to create the lambda client:

MyLambdaService lambdaService = LambdaInvokerFactory.builder().lambdaClient(AWSLambdaClientBuilder.defaultClient())
                    .lambdaFunctionNameResolver((method, annotation, config) -> "ENV_SPECIFIC_FUNCTION_NAME").build(MyLambdaService.class);

or

My method call "generalConfigHelper.getString("function_name"))" figure outs the correct function name according to the env (dev/qa/prod).

MyLambdaService lambdaService = LambdaInvokerFactory.builder().lambdaClient(AWSLambdaClientBuilder.defaultClient())
                .lambdaFunctionNameResolver((method, annotation, config) -> generalConfigHelper.getString("function_name")).build(MyLambdaService.class);

Official aws issue: https://github.com/aws/aws-sdk-java/pull/603

Daniel Gruszczyk · Accepted Answer · 2016-02-11 10:04:11Z

6

Some people might find it useful, this functionality is now included in 1.10.51 with use of LambdaFunctionNameResolver

answered Feb 11, 2016 at 10:04

Daniel Gruszczyk

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