[CentOS] What besides Postfix should not start until system time set?

Thu Apr 20 22:58:43 UTC 2017
Robert Moskowitz <rgm at htt-consult.com>

On 04/20/2017 06:17 PM, Warren Young wrote:
> On Apr 20, 2017, at 3:39 PM, Robert Moskowitz <rgm at htt-consult.com> wrote:
>> On 04/20/2017 05:16 PM, Warren Young wrote:
>>> On Apr 20, 2017, at 3:00 PM, Robert Moskowitz <rgm at htt-consult.com> wrote:
>>>> So I have learned that Postfix should delay until Chronyd has moved the system time from 0 to current.
>>> I think it’s more the case that CentOS is written with the assumption that you’re running it on a host with a battery-backed RTC
>> It is the Centos7 for arm SOCs.  RPi is one of the worst (in my opinion) of these.
> So you picked an alternative that cites “server stability” when explaining why they’re redirecting you to a Kim Dotcom service to get info about the product?  No, no, no.  No thank you.  No.
> http://dl.cubieboard.org/model/CubieBoard5/CB5%20Resource%20changed%20download%20%20server.txt
> That looks like a “Don’t stick your hand in this hole.” sign to me.

I got mine from a US supplier:


Fedora-arm and Centos-arm developers use the Cubietruck.  FWW.

>>>> Apache?
>>> Just speculating here, but my sense is that Apache doesn’t care about dates and times until it gets an HTTP request, in order to handle Expires headers and such correctly. And, HTTP being stateless, even if an HTTP request comes in so early that it gives the wrong answer, it should get back on track once the system clock is fixed.
>> On the Apache list, I was just told
>> "There are some parts of the HTTP conversation which could be affected by having the wrong time, but HTTPD itself doesn't care.
>> For example, if you are using cookies, caching, those could be affected by the time change (even more specifically, for PHP sessions, when the clock changes, the PHP session cleanup handler might think a session is very old and remove it).”
> That pretty much just backs up and amplifies my speculation: strange things will happen in the window where the clock is wrong, but operations will get on track quickly without restarting the web server once the clock changes out from under it.
> It is possible that some particular web apps won’t cope nicely, such as because they keep server time info on the client and then make later stateful comparisons, but that isn’t about Apache or PHP.

To delay httpd is no biggie.  To delay bind is a no-no.  To delay 
Postfix, apparently, is important.

There seems to be a way with the chronyd -s option to use the timestamp 
on the driftfile.  I need to look more into that.