Certificate volume

Nginx-LE stores certificates on a persistent volume which by convention is called certificates.
The certificates folder is mounted into the container at /etc/letsencrypt/.
It is critical that this is a persistent volume otherwise Nginx-LE will need to acquire a new certificate every time it starts.
nginx-le config will automatically create the volume but if you are using docker-compose or creating your own docker container you must create a persistent volume called certificates.
Lets Encrypt have hard limits (5 per day) on the no. of certificates you can acquire so if you don't have a persistent volume you will very quickly breach this limit.