Nginx转发到Flask应用scheme获取不到https

server {
    listen 80;
    server_name _;
    access_log  /var/log/nginx/access.log;
    error_log  /var/log/nginx/error.log;
    location / {
        proxy_pass         http://127.0.0.1:8000/;
        proxy_redirect     off;
        proxy_set_header   Host                 $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    $scheme;
    }
}

from werkzeug.middleware.proxy_fix import ProxyFix
app.wsgi_app = ProxyFix(app.wsgi_app, x_proto=1, x_host=1)