sample lamp setup using Docker compose
includes php web server + app (phpmyadmin), mysql server and nginx server
http://localhost:81/and login with: myuser / mypass
docker exec dockercomposelamp_mysql_1 ping -c2 nginxOR
docker-compose exec mysql ping -c2 nginx
pings nginx container from mysql, which you can see is not "linked" in docker-compose file.
You can see in the docker-compose.yml file, only port exposed to host is nginx, which uses 81 to avoid collisions with existing http. Feel free to change config options and see how they work for you.
Nginx link is simply:
phpmyadmin used here "off-the-shelf" as an example app since it's a self-contained, well-known php app that you can also use to interact with the db. You would generally replace this with your own custom php app image based off
php:5.6-apache (or similar).
NOTE: This is a simplified example designed for learning, not production. Use at your own peril.