Building RESTful Web Services with PHP 7

Logs should be centralized

You need to collect logs in some central place. If you have logs in one centralized place, then it is much easier to look into them instead of checking every server instance for its logs.

It is also important because you should have logs in an external place other than your instances as logs' backup. The reason is that if you replace an instance, then you probably want to keep a copy of your logs to utilize while debugging. This can be any place either Amazon S3, your DB, or a disk, but you want it to be durable and available. If you are on AWS, then you can also use their monitoring service named CloudWatch at https://aws.amazon.com/cloudwatch/.