web.conf

upstream http_backend {
  server web:3000;
  keepalive 32;
}

upstream prerender_backend {
  server prerender:3000;
  keepalive 32;
}

proxy_cache_path /var/lib/nginx/cache levels=1:2 keys_zone=cache:30m max_size=1G;

server {
  listen *:80;

  location /static/ {
    proxy_cache cache;
    proxy_cache_valid 30m;
    proxy_pass  http://http_backend;
  }

  location / {
    set $prerender 0;
    if ($http_user_agent ~* "baiduspider|twitterbot|facebookexternalhit|rogerbot|linkedinbot|embedly|quora link preview|showyoubot|outbrain|pinterest|slackbot") {
      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)") {
      set $prerender 0;
    }

    if ($prerender = 1) {
      rewrite .* /http://web:3000$request_uri? break;
      proxy_pass http://prerender_backend ;
    }

    if ($prerender = 0) {
      proxy_pass  http://http_backend;
    }

    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header Host $http_host;
  }
}