proxy host header in nginx code example

Example: nginx proxy pass

location /path/to/service/ {
  proxy_pass http://127.0.0.1:8081/;
  proxy_http_version 1.1;
  proxy_set_header Upgrade $http_upgrade;
  proxy_set_header Connection 'upgrade';
  proxy_set_header Host $host;
  proxy_cache_bypass $http_upgrade;
}