Create and package the Lambda function

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Create and package the Lambda function - AWS IoT Greengrass

AWS IoT Greengrass Version 1 entered the extended life phase on June 30, 2023. For more information, see the AWS IoT Greengrass V1 maintenance policy. After this date, AWS IoT Greengrass V1 won't release updates that provide features, enhancements, bug fixes, or security patches. Devices that run on AWS IoT Greengrass V1 won't be disrupted and will continue to operate and to connect to the cloud. We strongly recommend that you migrate to AWS IoT Greengrass Version 2, which adds significant new features and support for additional platforms.

In this step, you:

Create a Lambda function deployment package that contains the function code and dependencies.
Use the Lambda console to create a Lambda function and upload the deployment package.
Publish a version of the Lambda function and create an alias that points to the version.

On your computer, go to the AWS IoT Greengrass Core SDK for Python that you downloaded and extracted in Create and package a Lambda function in Module 3-1.

The Lambda function in this module uses:
- The greengrassHelloWorldCounter.py file in examples\HelloWorldCounter. This is your Lambda function code.
- The greengrasssdk folder. This is the SDK.
Create a Lambda function deployment package:
1. Copy the greengrasssdk folder into the HelloWorldCounter folder that contains greengrassHelloWorldCounter.py.
2. Save greengrassHelloWorldCounter.py and the greengrasssdk folder to a zip file named hello_world_counter_python_lambda.zip. The py file and greengrasssdk folder must be in the root of the directory.
  
  On UNIX-like systems (including the Mac terminal) that have zip installed, you can use the following command to package the file and folder:
```
zip -r hello_world_counter_python_lambda.zip greengrasssdk greengrassHelloWorldCounter.py
```
Now you're ready to create your Lambda function and upload the deployment package.
Open the Lambda console and choose Create function.
Choose Author from scratch.
Name your function Greengrass_HelloWorld_Counter, and set the remaining fields as follows:
- For Runtime, choose Python 3.7.
- For Permissions, keep the default setting. This creates an execution role that grants basic Lambda permissions. This role isn't used by AWS IoT Greengrass. Or, you can reuse the role that you created in Module 3-1.
Choose Create function.
Upload your Lambda function deployment package.
1. On the Code tab, under Code source, choose Upload from. From the dropdown, choose .zip file.
2. Choose Upload, and then choose your hello_world_counter_python_lambda.zip deployment package. Then, choose Save.
3. On the Code tab for the function, under Runtime settings, choose Edit, and then enter the following values.
  - For Runtime, choose Python 3.7.
  - For Handler, enter greengrassHelloWorldCounter.function_handler
4. Choose Save.
  
  Note
  The Test button on the AWS Lambda console doesn't work with this function. The AWS IoT Greengrass Core SDK doesn't contain modules that are required to run your Greengrass Lambda functions independently in the AWS Lambda console. These modules (for example, greengrass_common) are supplied to the functions after they are deployed to your Greengrass core.
Publish the first version of the function.
1. From the Actions menu at the top of the page, choose Publish new version. For Version description, enter First version.
2. Choose Publish.
Create an alias for the function version.
1. From the Actions menu at the top of the page, choose Create alias.
2. For Name, enter GG_HW_Counter.
3. For Version, choose 1.
4. Choose Save.
Aliases create a single entity for your Lambda function that Greengrass devices can subscribe to. This way, you don't have to update subscriptions with new Lambda function version numbers every time the function is modified.