Lambda calling lambda with trace id

index.js

// Lambda 1 - arv-foo
// Synchronous fn that will back API Gateway endpoint.

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

const getRandomInt = (max) => Math.floor(Math.random() * Math.floor(max));

exports.handler = async (event, context) => {
    console.log("event:", event)
    const traceId = (event.headers || {})["x-amzn-trace-id"] || getRandomInt(999999);
    
    const barPayload = {
        FunctionName: "arv-bar",
        Payload: JSON.stringify({ 
            caller: "Called from arv-foo",
            headers: {
               "x-amzn-trace-id": traceId, 
            },
        }),
        InvocationType: "Event",
    }
    
    const barResponse = await lambda.invoke(barPayload).promise();
    console.log('arv-bar response:', barResponse);

    const response = {
        statusCode: 200,
        body: JSON.stringify({ 
            message: 'Lambda arv-foo returning response',
            traceId,
        }),
    };
    return response;
};




// Lambda 2 - arv-bar
// Asynchronous worker fn that will do some hrd work.
exports.handler = async (event) => {
    console.log('arv-bar event:', event);
    await new Promise(r => setTimeout(r, 2000));
    const response = {
        statusCode: 200,
        body: JSON.stringify('Lambda arv-bar finished.'),
    };
    return response;
};



// Lambda 2 clouldwatch logs example:
2020-09-08T14:21:18.219Z	62b1bc63-2862-43a6-b0e6-44f1633b2e64	INFO	arv-bar event: {
  caller: 'Called from arv-foo',
  headers: { 'x-amzn-trace-id': 917093 }
}