I’m using Docker for Mac as my development platform and have php and apache containers managed by docker-compose (and so in their own private network) and then an nginx-proxy (jwilder’s one) for routing requests.
This all works fine when I first start everything but the php makes numerous requests to an external mariadb server and, over the space of a couple of hours as I develop and reload pages in the browser to test my code, the mariadb connections get slower and slower until almost 100% of them start timing out and I get an SQL timeout error. Restarting container groups makes no difference and the only fix is to quit docker for Mac and restart it.
As I’m sure you can understand, this is highly irritating 
I made a number of environment changes when switching to Docker for Mac 1.12 and also switched over to using v2 of the docker-compose config format with the container-group private networks so I’m afraid I can’t pin down which of a few changes caused the problem but my gut feeling is that it is related to the docker-compose private network groups.
Anyone else experienced this or know of a fix?