How to invoke a lambda function from a real time gamelift server

You should be able to use the AWS SDK from your script to interact with other AWS services. For this you'd need to additionally set up an IAM role with appropriate permissions to interact with Lambda (or other AWS services) and assign this role to your fleet. Any game server running on this fleet can then assume the role and interact with required services.

For more information, please refer: https://docs.aws.amazon.com/gamelift/latest/developerguide/gamelift-sdk-server-resources.html

Thanks!