prerender.io service nginx configuration

nginx.conf

# -*- mode: nginx; mode: flyspell-prog; mode: autopair; ispell-local-dictionary: "american" -*-

http {
    include mime.types;
    default_type application/octet-stream;

    #log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
    #                  '$status $body_bytes_sent "$http_referer" '
    #                  '"$http_user_agent" "$http_x_forwarded_for"';

    #access_log  logs/access.log  main;

    sendfile on;
    #tcp_nopush     on;

    #keepalive_timeout  0;
    keepalive_timeout 10;

    #gzip  on;

    map $http_user_agent $prerender_ua {
        default 0;
        ~*baiduspider 1;
        ~*twitterbot 1;
        ~*facebookexternalhit 1;
        ~*rogerbot 1;
        ~*linkedinbot 1;
        ~*embedly 1;
        '~*quora link preview' 1;
        ~*showyoubot 1;
        ~*outbrain 1;
        ~*pinterest 1;
        ~*slackbot 1;
    }

    map $uri $prerender {
        default  $prerender_ua;
        ~*_escaped_fragment_ 1;
    }

    map $prerender $route {
        0 @default;
        1 @prerender;
    }

    upstream prerender {
        server 127.0.0.1:3000;
        server [::1]:3000;
        keepalive 2;
    }

    upstream default_host {
        server example.com:443;
        keepalive 2;
    }

    server {
        listen 9999;
        server_name localhost;

        location @default {
            resolver 8.8.8.8;
            proxy_pass https://default_host;
            proxy_set_header Connection '';
            proxy_http_version 1.1;
            add_header X-Route default;
        }

        location @prerender {
            add_header X-Route prerender;
            rewrite ^ /https://example.com$request_uri break;
            proxy_set_header Connection '';
            proxy_http_version 1.1;
            # Proxy uri to running prerender.io instance.
            proxy_pass http://prerender;
        }

        location / {
            content_by_lua '
            ngx.exec(ngx.var.route)
            ';
        }
    }
}