httpd serving php

[Teno Deuter]

Dear support team,

in a OpenBSD 6.3 installation with php packges added, I have the
following httpd configuartion:

server "domain" {
        listen on * tls port 443
        listen on :: tls port 443
        tls {
                certificate "/etc/ssl/private/server.pem"
                key "/etc/ssl/server.key"
        }

        directory index index.php

        location "/pub/*" {
                directory auto index
        }

                root "/htdocs/domain"

        location "*.php" {
        fastcgi socket "/run/php-fpm.sock"
        }
}

the above generates a 500 error!

Also, no '/run/php-fpm.sock' exists!

Thank you for your help