In status quo, I have running aws ec2with ubuntu version 14.04
I’m going to update version to 16.04 and I recognize that sudo do-release-upgrade will help me to do that.
The reason for the ubuntu update, is to upgrade php5 to php7 and to lessen deprecated gems
However, my worries are that, 14.04 to 16.04 brings some significant changes, for example upstart to systemd, and since I have set many configurations related to nginx I want to know some possible changes, or failures following such update.
Also I want to know whether php7.0 perfectly substitute php5 legacies.
Currently php is only used for wrapping c coded 3rd parties, and using limitedly with php5-cli, php5-mcrypt. Are these replacable by version 7?
I cannot give you any specifics, but would recommend to use the beauty of the cloud: create an AMI snapshot of your instance and start in beside your original. Update ubuntu on the copy and see what you get.