Efficiently using multiple docker containers in a single host

Question

I have a physical server running Nginx, MySQL and serving my PHP website. The server has Multi-Core processor with 16 GB of RAM. This server can handle certain amount of web traffic.

Now instead of this single server, if I run multiple docker containers running individual instances of Nginx (App Server) and MySQL (DB Server) in it and load balance between the application and database containers, will it be able to handle the same amount of traffic as a single server handled it or would it be lesser (Performance wise)?

How will the performance be if I use a virtual server like EC2 or Digital Ocean Leaflet with the same hardware configuration instead of a physical server?

Answer 1

Since all process run on the native host (you can run ps aux on host outside container and see them). There should be very little overhead. The network bridging and IP Tables entries to forward packets to virtual host will add some CPU overhead but I can't imagine that being too onerous.

Answer 2

If the question is several nginx + 1 mysql versus several containers with each nginx + mysql, probably performance wise would be better not using containers, mainly because mysql and how much memory can have if is a single instance vs having multiple separate instances. You can anyway have the nginx in separate containers but using one central mysql for all sites, in a container or not.