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

Wed Dec 28 20:46:50 UTC 2016
whitivery <co55-sy1t at dea.spamcon.org>

whitivery <co55-sy1t at dea.spamcon.org> wrote:

>Jonathan Billings <billings at negate.org>
>>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.

Follow-up: with no other solution, I solved the problem externally.

I made an alias (actually, a shell function) for "service".  If the
interactive user is trying to start or restart the affected service, a
flag (sourced environment variable in a file under /etc/default) is set,
the real service binary is called, the initscript sees the flag and skips
the boot delay, then the "service" function restores the flag.

Less than ideal but it works.