Hi @rg305, thanks for the prompt reply.
Sorry but I couldn't understand the ports issue. From what I understood, the cert files are being written in an external/shared folder, therefore ports are not in use. Seems that nginx makes a copy of those cert files when the container is started, and just ignores whenever those files are updated.
Indeed, the initial idea was to have a single container with nginx and certbot together, but I faced some troubles trying to achieve this. While attempting this, I realized that having separeted containers would allow me to always apply latest certbot image while being fixed to a specific nginx image (required at our project for safety purposes).