aws-lambda-helper

aws-lambda-helper

Collection of helper methods for lambda

Installation

$ npm install aws-lambda-helper --save

Usage

  var AwsHelper = require('aws-lambda-helper');

  exports.handler = function(event, context) {
    ...
    //Initialise the helper by passing in the context
    AwsHelper.init(context);
    ...
  }

Invoke a Lamda function

  var AwsHelper = require('aws-lambda-helper');

  exports.handler = function(event, context){
    // assume : context.invokedFunctionArn = invokedFunctionArn: 'arn:aws:lambda:eu-west-1:123456789:function:mylambda:prod'

    //Initialise the helper by passing in the context
    AwsHelper.init(context);

    console.log(AwsHelper.env); //prints: prod
    console.log(AwsHelper.region); //prints: eu-west-1
    console.log(AwsHelper.account); //prints: 123456789

    var params = {
        FunctionName: 'MyAmazingLambda',
        Payload: { 'hello': 'world' },
        Qualifier: ''
      };
    AwsHelper.Lambda.invoke(params, function (err, data) {
      AwsHelper.failOnError(err, event, context);
      context.succeed(data);
    });
  }

fn: failOnError

This function will intercept the error if exists and then will call 'context.fail'. The purpose of this function is to avoid the need of checking for errors so that in callback you could just focus on the succesfull procedure.

It can be used as follows:

 AwsHelper.Lambda.invoke(params, function (err, data) {
      AwsHelper.failOnError(err, event, context);
      context.succeed(data);
  });
  

Logging JSON messages

var AwsHelper = require('aws-lambda-helper');

exports.handler = function(event, context){
  // assume : context.invokedFunctionArn = invokedFunctionArn: 'arn:aws:lambda:eu-west-1:123456789:function:mylambda:prod'

  //Initialise the helper by passing in the context
  AwsHelper.init(context, event);

  var log = AwsHelper.Logger('example');

  log.info();     // Returns a boolean: is the "info" level enabled?
  // This is equivalent to `log.isInfoEnabled()` or
  // `log.isEnabledFor(INFO)` in log4j.

  log.info('hi');                     // Log a simple string message (or number).
  log.info('hi %s', bob, anotherVar); // Uses `util.format` for msg formatting.

  log.info({foo: 'bar'}, 'hi');
  // The first field can optionally be a "fields" object, which
  // is merged into the log record.

  log.info(err);  // Special case to log an `Error` instance to the record.
  // This adds an "err" field with exception details
  // (including the stack) and sets "msg" to the exception
  // message.
  log.info(err, 'more on this: %s', more);
  // ... or you can specify the "msg".

  log.info({foo: 'bar', err: err}, 'some msg about this error');
  // To pass in an Error *and* other fields, use the `err`
  // field name for the Error instance.
}