Spring service in docker container cannot connect to mysql in docker container
change this url: jdbc:mysql://localhost:3306/MyDB to:
url: jdbc:mysql://db:3306/MyDBlocalhost refer here to your app container , compose will handel that to you by using service names
you need also to make sure that the DB is up and running before the APP container is , you can use somehting like wait-for-it.sh see this