[CentOS] CentOS 7 and systemd: SysV initscript: how detect boot vs. interactive use?

[whitivery]

Jonathan Billings <billings at negate.org>
wrote:

>On Sun, Dec 18, 2016 at 08:50:54PM -0800, whitivery wrote:
>> It is a system with several servers (various platforms/distros).
>> 
>> One piece of software runs on all of the servers.  For it to operate
>> correctly, the instance on one server (prime) must start before the others
>> (auxiliary).
>> 
>> So a boot delay is added (via a script sourced from initscript, which
>> first waits for network to come up) to set the boot delay values for each
>> server - prime at 0, others at some other value of 15 to 110 seconds
>> depending on platform.
>> 
>> But when it is necessary to manipulate the service interactively via the
>> "service" command, the boot delay needs to be bypassed.
>
>Well, the first thing I'd do is make the service wait for the network
>to be online.  In the [Unit] section add Wants=network-online.target.
>
>Secondly, I'd try to find a way for the auxiliary services to ping the
>prime service to ensure its up, and make that script a ExecStartPre
>entry in the [Service] section.  You'll want to adjust the
>TimeoutStartSec in case it might exceed the DefaultTimeoutStartSec in
>/etc/systemd/system.conf, which is 90 seconds.

Thank you for the idea, but as mentioned, the same service runs on a mix
of server platforms and distros, and the older ones do not use systemd, so
I'd prefer to stick with SysV type initscripts that work on all of them.