If you would like to programatically find the current image of a specific distribution in AWS for your region, with the use of the aws cli, use the following (in this example looking for Ubuntu 16.04).
SHELL
x
aws ec2 describe-images \ --owners 099720109477 \ --filters "Name=name,Values=ubuntu/images/hvm-ssd/ubuntu-xenial-16.04-amd64-server-????????" "Name=state,Values=available" \ --query "reverse(sort_by(Images, &CreationDate))[:1].ImageId" \ --output textOr for 18.04
SHELL
aws ec2 describe-images \ --owners 099720109477 \ --filters "Name=name,Values=ubuntu/images/hvm-ssd/ubuntu-bionic-18.04-amd64-server-????????" "Name=state,Values=available" \ --query "reverse(sort_by(Images, &CreationDate))[:1].ImageId" \ --output textThis is from the examples in the documentation here: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/finding-an-ami.html