How to invoke a Lambda from another Lambda correctly

Question

I try to invoke a “child” lambda from a “parent” lambda

The example of code is very simple as below (I am using Serverless framework).

child_lambda

const mainHandler = async (event, context) => {
    console.log('event: ', JSON.stringify(event));    
    return context.functionName;
  };
export const handler = mainHandler;

parent_lambda

import AWS from 'aws-sdk';
const lambda = new AWS.Lambda();

const invokeLambda = async () => {
  let sampleData = { number1: 1, number2: 2 };

  let params = {
    FunctionName: 'child_lambda',
    Payload: JSON.stringify(sampleData),
    Qualifier: '1'
  };

  try {
    await lambda.invoke(params).promise();
    return true;
  } catch (e) {
    console.log('invokeLambda :: Error: ' + e);
  }
};

const mainHandler = async (event, context) => {
  console.log('event: ', JSON.stringify(event));
  await invokeLambda();
  return context.functionName;
};

export const handler = mainHandler;

serverless.yml

parent_lambda:
    handler: handlers/lambda/parent_lambda.handler
    name: dev_parent_lambda
    iamRoleStatements:
      - Effect: "Allow"        
        Action:
          - lambda: InvokeFunction
          - lambda: InvokeAsync   
        Resource: "*"
    events:
      - http:
          path: test/invokeLambda
          method: GET

child_lambda:
    handler: handlers/lambda/child_lambda.handler
    name: dev_child_lambda

I run the parent from Postman and the result is

ResourceNotFoundException: Function not found: arn:aws:lambda:xxxx:xxxxx:function:dev_child_lambda

I tried to trigger the child_lambda from an S3 event, it worked fine, but never work with invoke as AWS SDK.

Any suggestion is appreciated

user_10186808 · Answer

From the comments, code given in the question is perfect except the Qualifier parameter

Qualifier is used to

Specify a version or alias to invoke a published version of the function.

In this case, lambda is not versioned. Hence we just need to remove qualifier .

const invokeLambda = async () => {
  let sampleData = { number1: 1, number 2: 2 };

  let params = {
    FunctionName: 'child_lambda',
    Payload: JSON.stringify(sampleData)
  };

  try {
    await lambda.invoke(params).promise();
    return true;
  } catch (e) {
    console.log('invokeLambda :: Error: ' + e);
  }
};

user_2246345 · Answer

Lambda Asynchronous invocation

Amazon Simple Storage Service (Amazon S3) invoke functions asynchronously to process events. When you invoke a function asynchronously, you don't wait for a response from the function code. You hand off the event to Lambda and Lambda handles the rest.

In that case, I would simply chain the lambdas using AWS lambda destinations. Supported destinations:

Amazon SQS – sqs:SendMessage
Amazon SNS – sns:Publish
Lambda – lambda:InvokeFunction
EventBridge – events:PutEvents

Configuring destinations for asynchronous invocation

Introducing AWS Lambda Destinations

How to invoke a Lambda from another Lambda correctly

2 Answers