This so far has been working for me to have DroneCI behind an NGiNX reverse proxy working with Gitea

NGiNX Code

nano /etc/nginx/sites-available/

ln -s /etc/nginx/sites-available/ /etc/nginx/sites-enabled

upstream droneci {
server {

        listen 443 ssl http2;
        ssl_certificate            /etc/certs/;
        ssl_certificate_key        /etc/certs/;
        ssl_session_cache  builtin:1000  shared:SSL:10m;
        ssl_protocols TLSv1.2 TLSv1.3;

        location / {
                proxy_set_header X-Forwarded-For $remote_addr;
                proxy_set_header X-Forwarded-Proto $scheme;
                proxy_set_header Host;
                proxy_pass http://droneci;
                proxy_redirect off;
                proxy_http_version 1.1;
                proxy_buffering off;
                chunked_transfer_encoding off;

Here is the code for the docker container

docker run \
--volume=/var/lib/drone:/data \
--env=DRONE_SERVER_PROTO="https" \
--publish=8080:80 \
--restart=always \
--detach=true \
--name="" \