[CentOS] systemd

Wed Jan 9 17:04:29 UTC 2019
Steve Clark <steve.clark at netwolves.com>

On 01/09/2019 11:36 AM, Jonathan Billings wrote:
> On Wed, Jan 09, 2019 at 10:43:38AM -0500, Steve Clark wrote:
>> I am trying to understand what After= means in a unit file. Does it
>> mean after the specified target is up and operational or only that
>> the target has been started? 
>> I have something that needs postgres but postgres needs to be
>> operational not just started. Sometimes it can take a bit for
>> postgres to become operational. 
> I believe that the postgresql service has Type=notify in it's service
> definition, which means that it will notify systemd when it is
> operational.  This means that if you have a service that has
> After=postgresql.service, systemd should wait until after the
> postgresql service notifies systemd that it is operational before your
> service will be started.
> If your service is starting and unable to connect to postgresql, then
> I would say that's a bug in postgresql -- it shouldn't be notifying
> systemd that it is operational until it actually is.
I don't see that in the postgresql.service file - this is CentOS Linux release 7.5.1804 (Core)

from /usr/lib/systemd/system/postgresql.service