Hello Maxim.

> nginx does not care if the upstream socket is reacheable or not
> when it parses configuration, it is only important when processing
> a particular request. That is, nginx can (and will) start just
> fine if the socket doesn't exist (or, similarly, upstream server's
> IP address isn't reachable). And that's what "nginx -t"
> checks for: if nginx itself will be able to start.
>
> […]
>
> If your use case is simple enough and you want both nginx and
> corresponding PHP-FPM processes to be running at the same time,
> and, for example, don't want to start nginx if PHP-FPM isn't
> running - this is something to check by means external to nginx.

Perfect answer - thank you very much for your clarification.

With gratitude and best wishes,

Pete