nginx.conf

server {
    listen 80 default_server;
    listen [::]:80 default_server ipv6only=on;

    server_name _;

    root /home/app/build;
    passenger_enabled on;
    passenger_user app;

    index  index.html;

    gzip on;
    gzip_disable "MSIE [1-6]\.(?!.*SV1)";

    gzip_vary on;
    gzip_proxied any;
    gzip_comp_level 6;
    gzip_buffers 16 8k;
    gzip_http_version 1.1;
    gzip_types text/plain text/html text/css application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript application/javascript text/x-js;

    # Expire rules for static content

    # https://rtcamp.com/wordpress-nginx/tutorials/plugins/yoast-seo-sitemap/
    location ~ ([^/]*)sitemap(.*)\.x(m|s)l$ {
        proxy_pass ${API_BASE_URL};
        access_log off;
    }

    location ~ ([^/]*)rss(.*)\.x(m|s)l$ {
        proxy_pass ${API_BASE_URL};
        access_log off;
    }

    # cache.appcache, your document html and data
    location ~* \.(?:manifest|appcache|html?|xml|json)$ {
      expires -1;
      # access_log logs/static.log; # I don't usually include a static log
    }

    # Media: images, icons, video, audio, HTC
    location ~* \.(?:jpg|jpeg|gif|png|ico|cur|gz|svg|svgz|mp4|ogg|ogv|webm|htc)$ {
      expires 1M;
      access_log off;
      add_header Pragma public;
      add_header Cache-Control "public, must-revalidate, proxy-revalidate";
    }

    # CSS and Javascript
    location ~* \.(?:css|js)$ {
      expires 1y;
      access_log off;
      add_header Cache-Control "public";
    }

    location / {
        try_files $uri @prerender;
    }

    location @prerender {
        proxy_set_header X-Prerender-Token ${PRERENDER_TOKEN:-000000000};

        set $prerender 0;
        if ($http_user_agent ~* "baiduspider|facebot|twitterbot|facebookexternalhit|rogerbot|linkedinbot|embedly|quora link preview|showyoubot|outbrain|pinterest|slackbot|vkShare|W3C_Validator") {
            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|svg|flv|m4v|torrent|ttf|woff)") {
            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;
        }
    }

    location = /static/favicon.ico {
        access_log off;
        log_not_found off;
    }

}