The AWS Greengrass Core SDK for JavaScript allows developers to write JavaScript Lambda functions which will run within Greengrass.
This document provides instructions for preparing your Greengrass Core environment to run Lambda functions written in JavaScript. It also includes examples on how to develop a Lambda function in JavaScript as well as packaging and running an example Hello World file in JavaScript for your Greengrass core.
The environment where Greengrass is running on needs to be able to run NodeJS 8.10 applications.
- Install NodeJS 8.10 for your platform. You can download the newest NodeJS from https://nodejs.org/en/download/.
- When you untar the package downloaded from NodeJS website, you will find
node
file underbin
directory. - Copy the file to /usr/bin or /usr/local/bin folder.
- Rename the file to nodejs8.10
- Make sure the file is not a symlink.
- Copy
samples/HelloWorld
folder to your workspace. - Create a folder
node_modules
underHelloWorld
folder. - Unzip aws-greengrass-core-sdk-js.zip into the folder. It should create a folder HelloWorld/node_modules/aws-greengrass-core-sdk
- Zip up the content of HelloWorld folder so that the index.js is on the top of the zip file structure.
- Go to AWS Lambda Console.
- Create a new function.
- Choose the Runtime as
Node.js 8.10
- Upload the zip file in Lambda function code section.
- Handler is index.handler
- Choose any role as the role is not used within Greengrass.
- After creating the function, publish the Lambda.
- Create an Alias and point to the Published version (not $LATEST).
- Go to your Greengrass Group and add the Lambda under Lambdas section.
- Click on the Lambda and change the Lambda lifecycle to Make this function long-lived and keep it running indefinitely.
- Add a Subscription with the following configuration:
- Source: Lambda which you just created and added to the group
- Target: IoT Cloud
- Topic: hello/world
- Deploy. A message from your Lambda should be published to the topic hello/world in the cloud every 5 seconds. You can check this by going to AWS IoT's Test page and subscribing to topic hello/world.
Unzip the SDK into your node_modules folder of your function. This should create a aws-greengrass-core-sdk folder which includes the SDK.
Your console.log operation will be logged as INFO. A console.error operation will be logged as ERROR. Currently, our NodeJS SDK only allows you to log at INFO or ERROR level only.
From GGC version 1.5, you can send both JSON and binary data as a payload when you invoking other Lambdas or publishing a message using IotData service. In order to make your lambda be able to handle binary payload, you need to configure the lambda in Greengrass console to mark it using binary input payload so that GGC can know how to deal with the data.
In Greengrass, you can send a context object in a JSON format to be passed to another Lambda that is being invoked. The context format looks like this: { custom: { customData: 'customData', }, }
Compatibility¶
As new features are added to AWS Greengrass, previous versions of the Greengrass SDK will be incompatible with newer versions of the AWS Greengrass core. The following table lists the compatible SDKs for all GGC releases.
GGC Version | Compatible SDK Versions |
---|---|
1.0.x-1.6.x | 1.0.x-1.2.x |
1.7.x-1.8.x | 1.0.x-1.3.x |
1.9.x | 1.0.x-1.4.x |
1.4.0 Updates¶
Added support for Node.js 8.10 Lambda runtime. Lambda functions that use Node.js 8.10 runtime can now run on an AWS IoT Greengrass core. (Existing Lambda functions that use Node.js 6.10 runtime can still run on Greengrass core, but they can’t be updated after 5/30/2019. Please refer to AWS Lambda Runtimes Support Policy.)
1.3.1 Updates¶
Improved log level granularity.
1.3.0 Updates¶
SDK supports SecretsManager client.
1.2.0 Updates¶
SDK and GGC compatibility check takes place in the background.
1.1.0 Updates¶
Lambda only accepted payload in JSON format. With this update, Invoking or publishing binary payload to a lambda is supported.
1.0.1 Updates¶
SShadow operations were not receiving responses from the local shadow properly. This has been fixed.
Lambda Invoke function's InvocationType's default value was Event. This has been changed to RequestResponse.
Apache 2.0