Question

Nginx 1.1.4+ can serve upstream connection with HTTP1.1 keepalive directive, see the official documentation (it’s not the same as keepalived clients’ connections). So the Unicorn configuration can look like as below:

upstream unicorn {
  server             unix:/tmp/unicorn.todo.sock fail_timeout=0;
  keepalive          4;
}

server {
  try_files          $uri/index.html $uri @unicorn;
  keepalive_timeout  70;

  location @unicorn {
    proxy_set_header   X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header   Host $http_host;
    proxy_redirect     off;
    proxy_pass         http://unicorn;

    proxy_http_version 1.1;
    proxy_set_header   Connection "";
  }
}

These headers are required for HTTP connection: proxy_http_version and proxy_set_header.

So the question is the configuration valid or socket-connection is permanent by itself?

Answer 1

Yes, it’s valid. There’s no difference between UNIX-socket and TCP/IP-socket in terms of HTTP Keepalive.