Если я вас правильно понял, то вот ваш конфиг.

server {
listen 443;
ssl on;
server_name example.com;
ssl_certificate /etc/tunnel/your.pem;
ssl_certificate_key /etc/tunnel/your.key;
ssl_session_timeout 10m;
ssl_ciphers RC4:HIGH:!aNULL:!MD5;
ssl_prefer_server_ciphers on;
ssl_session_cache builtin;

location / {
proxy_pass http://localhost:8090;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";

}