Страница-заглушка (maintenance)

Сниппет конфигурации подготовлен Володей.

Вставляем в location / {}:

        if (-f /tmp/ramdisk/postcards2020-graylog.preprod.appworks.ru.maintenance) { return 403; }
        error_page 403 /sf-access-denied.html;
        location = /sf-access-denied.html {
            add_header 'Cache-Control' 'no-store, no-cache, must-revalidate, proxy-revalidate, max-age=0'; expires off;
            root /srv/sites/sf_error_pages;
        }

Вариант, который я использовал для appindex.ru.

vim /etc/nginx/conf.d/include_appindex/maintenance.cfg

# appindex.ru - maintenance

if (-f /tmp/maintenance_flags/appindex.maintenance) { return 523; }

error_page 523 /maintenance.html;

location = /maintenance.html {
    add_header 'Cache-Control' 'no-store, no-cache, '
               'must-revalidate, proxy-revalidate, max-age=0';
    expires off;
    root   /srv/sites/appindex.ru/public_html;
}

vim /etc/nginx/conf.d/appindex.ru.conf

    location / {
        include /etc/nginx/conf.d/generic/proxy-pass-params.cfg;

        # This include can enable maintenance mode using flag file
        include /etc/nginx/conf.d/include_appindex/maintenance.cfg;

        proxy_pass http://appindex-cluster$request_uri;
    }