[PING^2] RFC [PATCH] BZ#1077902: New API gettimezone

[Paul Eggert]

On 05/01/2014 12:05 AM, Carlos O'Donell wrote:
> getenv ("TZ"); right now on an OpenShift gear returns "", and if I 
> pass my cartridge to someone running in Mumbai, and they use it the 
> chroot'd process prints the wrong time. 

If getenv ("TZ") returns the empty string both here and in Mumbai, glibc 
localtime will use UTC in both places, so you should be OK.

> How do I get the TZ out of the running system?

getenv ("TZ").

> Sure, but what do I set TZ to?

Whatever you want.  If you're trying to recreate your local environment 
on a remote host, set TZ to the same value as the local host, or leave 
it unset if it's unset on the local host.  So long as your tz files are 
the same in both places, this should work.

> It seems way more sensible to just provide the missing symmetric 
> portion of the API than to say "You just have to get all other distros 
> or frameworks you use to set TZ."

You don't need to get all other distros or frameworks.  Just ensure that 
your tz files are the same in both places.  Which is something you need 
to do *anyway*, if you want TZ settings to work the same in both places.

> On top of all this copying in /etc/localtime for say Docker containers 
> forces a COW for the changed file

That's a minor optimization issue, one that comes up with any sort of 
configuration file, not just time zones.  So you can address it the same 
way you address it for the rest of your configuration.  If it were me, 
I'd simply remove /etc/localtime from all the hosts in question, as 
that's easier to administer and is faster at runtime. But if someone 
wants all their servers to report Mumbai localtime, then whatever floats 
their boat....