map $http_x_forwarded_proto $proxy_x_forwarded_proto {
  default $http_x_forwarded_proto;
  ''      $scheme;
}

server {
    listen 80;

    location / {
        gzip off;

        client_max_body_size 50M;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        proxy_set_header Host $http_host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $proxy_x_forwarded_proto;
        proxy_set_header X-Frame-Options SAMEORIGIN;
        proxy_pass http://app:APP_PORT;
    }
}