option to wait for pid file to appear

[h.reindl@xxxxxxxxxxxxx (Reindl Harald)]

Am 17.05.2018 um 11:25 schrieb Igor Bukanov:
> I have a service unit for nginx that uses Type=forking and PIDFile.
> That works, but occasionally I see in the log a message like
> 
> nginx.service: PID file /run/nginx/nginx.pid not readable (yet?) after
> start: No such file or directory
> 
> After investigating this father I see the reason for this is that
> nginx creates the pid file in a child process, not in the parent (at
> least this is how I interpret their code). As the parent may exit and
> systemd may respond to it before the child writes the pid, that leads
> to the above message.
> 
> I can workaround that via replacing ExecStart=/usr/sbin/nginx with
> something like:
> 
> ExecStart=/bin/sh -c "set -e; /usr/sbin/nginx; while ! test -s
> /run/nginx/nginx.pid; do sleep 0.1; done'
> 
> but that busy waits. Is there any option to replace this hack via a
> native systemd solution, like explicitly waiting for the pid file to
> appear before considering the unit ready?

this is a bug in nginx

however, after many years with systemd on Fedora one needs yet to show
me a service where you can't simply remove the PIDFile line and you are done