This will create one public subnet and three private subnet. proxy server and a management instance for sshing to the instance in private subnet will be created in the public subnet.
Add the key value pair in the terraform.tfvars as below
key_pair_name = "<your_key_pair_name_here>"
ssh into the management instance and then ssh into the instance in the private subnet. curl https://www.google.com
You can tail the logs in the proxy server tail -F -n0 /var/log/squid/access.log