Things I've learn this week

  • May 12, 2015

More than often I find myself trying to remember how did i solve that very one problem I thought I would have to solve only once, so I decided to start writing their solution here:

* How to reload PHP-fpm without restarting it
* How to send the unchanged Host header to proxied server with Nginx

How to send the unchanged Host header to proxied server with Nginx

Imagine you have a first nginx acting as a load balancer with this configuration

upstream blue  {
    ...
}

upstream green  {
    ...
}

server {
    include /etc/nginx/backend.conf;

    location / {
        proxy_pass  http://blue;
        proxy_connect_timeout   5;
    }
}

if you do like that, with blue and green hosting your app, your application code will see “blue” or “green” as the http Host header, which may cause problem when creating absolue URL

you can override this, and force nginx to send the Host given by the client to the proxied server unchanged by adding one line like this:

    location / {
        proxy_pass  http://$activeBackend;
        proxy_set_header Host   $http_host; # <= this line
        proxy_connect_timeout   5;
    }

How to reload PHP-fpm without restarting it

In production you may want to reload php-fpm without restarting it in order to avoid downtime.

You can do this by sending the unix signal SIGUSR2 to the PID of php-fpm

It may provde useful when

  • updating the php.ini
  • if you to clear the opcache
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