There are a variety of docker containers available which integrate letsencrypt and nginx. Personally I use the linuxserver.io letsencrypt container to proxy my personal projects. You specify the domain names you need a certificate for at container startup via an environment variable and it takes care of getting the certificate issued and renewing as needed. Restarting with additional names added or names removed will result in the previous certificate being revoked and a new one issued as appropriate. This replaced my use of caddy for my personal projects about 3 weeks ago. A decision I debated before making and am now glad I made.