hyprstack hyprstack - 5 months ago 36
Node.js Question

Nodejs - Invoke an AWS.Lambda function from within another lambda function

I have the following function which I use to invoke a lambda function from within my code.

However when I try to use it within a lambda function, I get the following error:

AWS lambda undefined 0.27s 3 retries] invoke({ FunctionName: 'my-function-name',
InvocationType: 'RequestResponse',
LogType: 'Tail',
Payload: <Buffer > })


How can I invoke a lambda function from within a lambda function?

My function:

'use strict';

var AWS = require("aws-sdk");

var lambda = new AWS.Lambda({
apiVersion: '2015-03-31',
endpoint: 'https://lambda.' + process.env.DYNAMODB_REGION + '.amazonaws.com',
logger: console
});

var lambdaHandler = {};

// @var payload - type:string
// @var functionName - type:string
lambdaHandler.invokeFunction = function (payload, functionName, callback) {

var params = {
FunctionName: functionName, /* required */
InvocationType: "RequestResponse",
LogType: "Tail",
Payload: new Buffer(payload, 'utf8')
};

var lambdaRequestObj = lambda.invoke(params);

lambdaRequestObj.on('success', function(response) {
console.log(response.data);
});

lambdaRequestObj.on('error', function(response) {
console.log(response.error.message);
});

lambdaRequestObj.on('complete', function(response) {
console.log('Complete');
});

lambdaRequestObj.send();

callback();
};

module.exports = lambdaHandler;

Answer

Invoking a Lambda Function from within another Lambda function is quite simple using the aws-sdk. We are doing this in our projects including DynamoDB lookups in the invoked function.

I suggest starting with something simple first.
This is the "Hello World" of intra-lambda invocation:

Lambda_A invokes Lambda_B with a Payload containing a single parameter name:'Alex'.
Lambda_B responds with Payload: "Hello Alex".

lambda invoke

First create Lambda_B which expects a name property on the event parameter
and responds to request with "Hello "+event.name:

Lambda_B

exports.handler = function(event, context) {
  console.log('Lambda B Received event:', JSON.stringify(event, null, 2));
  context.succeed('Hello ' + event.name);
};

Ensure that you give Lambda_B and Lambda_A the same role.
E.g: create a role called lambdaexecute which has both AWSLambdaExecute and AWSLambdaBasicExecutionRole (for some reason both were required):

lambda-role-for-intra-lambda-execution

Lambda_A

var AWS = require('aws-sdk');
AWS.config.region = 'eu-west-1';
var lambda = new AWS.Lambda();

exports.handler = function(event, context) {
  var params = {
    FunctionName: 'Lambda_B', // the lambda function we are going to invoke
    InvocationType: 'RequestResponse',
    LogType: 'Tail',
    Payload: '{ "name" : "Alex" }'
  };

  lambda.invoke(params, function(err, data) {
    if (err) {
      context.fail(err);
    } else {
      context.succeed('Lambda_B said '+ data.Payload);
    }
  })
};

Once you have saved both these Lambda functions, Test run Lambda_A:

lambda invoke-lambda_a-execution-result

Once you have the basic intra-lambdda invocation working you can easily extend it to invoke more elaborate Lambda functions.

The main thing you have to remember is to set the appropriate ARN Role for all functions.

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