Invoke a lambda function from another lambda asynchronously for a string of input with different parameters using Java

Question

I need to call my lambda - A from lambda - B. I have done the required code but need few clarifications.

AWSLambda lambdaClient = AWSLambdaClientBuilder.standard().withRegion(region)
.withCredentials(new DefaultAWSCredentialsProviderChain()).build();

InvokeRequest request = new InvokeRequest().withClientContext(clientContext).withFunctionName(functionName)
          .withQualifier(alias).withPayload(payload).withInvocationType(InvocationType.Event);

InvokeResult response = lambdaClient.invoke(request);

I have a N number of table names which I need to pass from lambda B to lambda A one by one so that it can do the needful work on that DDB table.

The problem is withPayload takes a JSON payload which is passed to the lambda function.

I will pass the payload to lambda-B but then the code is calling lambdaClient.invoke(request) which will have all the table names and it will call our lambda-A. But handler function in the lambda-A expects a single table name.

I am not sure how to do this.

Also do i need to run this in a loop so that every time it takes new payload value and then calls lambdaClient.invoke(request) or does it happen automatically?

Shivang Agarwal · Answer 1 · 2019-06-06T09:05:41.723

-1

You should create pyload with a single table name. In this case, you will have many payloads so you can have array of them and process them in a loop.

For Example:

InvokeRequest request = null;
InvokeResult response = null;
for(String payload : payloads){
  request = new InvokeRequest().withClientContext(clientContext).withFunctionName(functionName)
          .withQualifier(alias).withPayload(payload).withInvocationType(InvocationType.Event);
  response = lambdaClient.invoke(request);
}

In which case you will get that payload? Lamda normally runs on some event and a lambda cannot run more than 15 minutes(For more than 15 minutes you have to contact the AWS Support Team).

edited Jun 06 '19 at 09:05

answered Jun 06 '19 at 08:31

Shivang Agarwal

1,825
1
14
19

lambda timeout has increased to 15 minutes. – testMyUnderstanding Jun 06 '19 at 08:41
@testMyUnderstanding updated the time but have you got your answer? – Shivang Agarwal Jun 06 '19 at 09:07
I think so.. I will have to try out. The problem is I am getting the payload from CF template. I need to check now how to pass array using template. – testMyUnderstanding Jun 06 '19 at 09:38
@testMyUnderstanding you can fetch the data from that payload and make your own payload. use JSON library for the same. – Shivang Agarwal Jun 06 '19 at 09:40
I am thinking to maintain a properties file which will have my tablenames in an array.. then I can pass that array to my CF template's environment variable and this way i can get it in my lambda function – testMyUnderstanding Jun 06 '19 at 09:46
@testMyUnderstanding Do these table names are static? Another point is how are you triggering your Lambda B? – Shivang Agarwal Jun 06 '19 at 11:29

Invoke a lambda function from another lambda asynchronously for a string of input with different parameters using Java

1 Answers1