prerender-nginx.conf

location @prerender {
    proxy_set_header X-Prerender-Token {token};

    set $prerender 0;
    if ($http_user_agent ~* "googlebot|bingbot|yandex|baiduspider|twitterbot|facebookexternalhit|rogerbot|linkedinbot|embedly|quora link preview|showyoubot|outbrain|pinterest\/0\.|pinterestbot|slackbot|vkShare|W3C_Validator|whatsapp") {
        set $prerender 1;
    }
    if ($args ~ "_escaped_fragment_") {
        set $prerender 1;
    }
    if ($http_user_agent ~ "Prerender") {
        set $prerender 0;
    }
    if ($uri ~* "\.(js|css|xml|less|png|jpg|jpeg|gif|pdf|doc|txt|ico|rss|zip|mp3|rar|exe|wmv|doc|avi|ppt|mpg|mpeg|tif|wav|mov|psd|ai|xls|mp4|m4a|swf|dat|dmg|iso|flv|m4v|torrent|ttf|woff|svg|eot)") {
        set $prerender 0;
    }

    #resolve using Google's DNS server to force DNS resolution and prevent caching of IPs
    resolver 8.8.8.8;

    if ($prerender = 1) {

        #setting prerender as a variable forces DNS resolution since nginx caches IPs and doesnt play well with load balancing
        set $prerender "service.prerender.io";
        rewrite .* /$scheme://$host$request_uri? break;
        proxy_pass http://$prerender;
    }
    if ($prerender = 0) {
        rewrite .* /index.html break;
    }
}