I am trying to stuff as many lamp stack containers inside docker as possible that are running wordpress. According to many sources it is possible to stuff over 500 containers on a docker server, for example:
However, they most likely discuss empty docker containers and not LAMP stack ones (apache+mysql).
I have managed to stuff 120 containers running wordpress and don't see a siginifcant issue with RAM or CPU. I should be able to fit more but performance goes downhill in response times after that point.
A colleague has mentioned that mysql performs significant I/O operations which could cause issues with file descriptors / open file limits / and fs.io.max.nr .
Could this be the case? Could it be that the number of open files of each containers limits the total number of containers?