Nginx S3/Unicorn Proxy with backend keep alive

nginx.conf

# The Nginx configuration based on https://coderwall.com/p/rlguog

http {

  ssl_certificate            server.crt;
  ssl_certificate_key        server.key;
  ssl_session_timeout        15m;
  ssl_protocols              SSLv3 TLSv1 TLSv1.1 TLSv1.2;
  ssl_prefer_server_ciphers  on;
  ssl_session_cache          shared:SSL:10m;
  ssl_stapling               on;

  resolver                   172.16.0.23 valid=300s;
  resolver_timeout           10s;
  proxy_cache_path           /tmp/cache levels=1:2 keys_zone=S3_CACHE:10m inactive=48h max_size=1000m;
  proxy_temp_path            /tmp/cache/temp;


  upstream unicorn {
    server                   unix:/tmp/unicorn.sock fail_timeout=0;
    keepalive                20;
  }


  upstream s3 {
    server                   'bucket.s3-eu-west-1.amazonaws.com:80';
    keepalive                10;
  }


  server {
    ...

    location @unicorn {
      proxy_set_header       X-Forwarded-For $proxy_add_x_forwarded_for;
      proxy_set_header       X-Forwarded-Proto $scheme;
      proxy_set_header       Host $http_host;
      proxy_redirect         off;

      proxy_http_version     1.1;
      proxy_set_header       Connection "";
      proxy_pass             http://unicorn;
    }


    location ~* ^/s3/(.*) {
      proxy_set_header       Host 'bucket.s3-eu-west-1.amazonaws.com';
      proxy_set_header       Authorization '';
      proxy_hide_header      x-amz-id-2;
      proxy_hide_header      x-amz-request-id;
      proxy_hide_header      Set-Cookie;
      proxy_ignore_headers   "Set-Cookie";
      proxy_intercept_errors on;

      proxy_cache            S3_CACHE;
      proxy_cache_valid      200 24h;
      proxy_cache_valid      403 15m;
      proxy_cache_bypass     $http_cache_purge;
      add_header             X-Cached $upstream_cache_status;

      proxy_http_version     1.1;
      proxy_set_header       Connection "";
      proxy_pass             http://s3/$1;
    }
  }

}