add existing things to a Greengrass group

Figured it out.
This shows a scenario of 100 sensors to Greengrass.

https://gambitcomm.blogspot.com/2019/10/dynamic-real-time-predictable-testing.html

Hi uwegambitcomm,

I am glad you figured it out.

For others that may be running into this issue, Greengrass APIs use versioned resources so it will take several API calls.

You would need to use the following APIs:

GetGroup: https://docs.aws.amazon.com/greengrass/latest/apireference/getgroup-get.html to get the latest version

GetGroupVersion: https://docs.aws.amazon.com/greengrass/latest/apireference/getgroupversion-get.html to get the versioned resources in that group. You will use this to get the device definition version id.

https://docs.aws.amazon.com/greengrass/latest/apireference/getdevicedefinitionversion-get.html - you get the list of devices from the device definition.

https://docs.aws.amazon.com/greengrass/latest/apireference/createdevicedefinitionversion-post.html - you will create a new list of devices using this API and it will return a new device definition id

https://docs.aws.amazon.com/greengrass/latest/apireference/creategroupversion-post.html - you will create a new group version with the new device definition id.

Then you would need to create a deployment using the CreateDeployment api:
https://docs.aws.amazon.com/greengrass/latest/apireference/createdeployment-post.html
This takes the group version id