nginxでメンテナンスページを表示させる。改良版 ref: https://qiita.com/kooohei/items/095eb1304f9fa67ed1a1

maintenance

error_page 500 @maintenance;

# Set Env
set $maintenance "on";

# Allow Paths
if ($uri ~ "^/exclude/") {
  set $maintenance "off";
}

# Allow IPs
if ($remote_addr ~ "xxx.xxx.xxx.xxx") {
  set $maintenance "off";
}
if ($http_x_forwarded_for ~ "xxx.xxx.xxx.xxx") {
  set $maintenance "off";
}

# maintenance
if ($maintenance = "on") {
  return 500;
}
location @maintenance {
  rewrite ^(.*)$ /maintenance.html break;
}

nginx.conf(追記)

# include /etc/nginx/conf.d/maintenance;
rewrite ^/maintenance.html(.*)$ https://$host/ permanent