Re: [PATCH] pg_isready (was: [WIP] pg_ping utility)

On Sat, Jan 26, 2013 at 12:39 PM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
> 2013/1/26 Phil Sorber <phil(at)omniti(dot)com>:
>> On Sat, Jan 26, 2013 at 11:53 AM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
>>> 2013/1/26 Phil Sorber <phil(at)omniti(dot)com>:
>>>> On Sat, Jan 26, 2013 at 4:02 AM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
>>>>> Hello
>>>>>
>>>>> We now haw to solve small puppet issue, because our puppets try to
>>>>> start server too early, when old instance live still.
>>>>>
>>>>> Maybe some new parameter - is_done can be useful.
>>>>>
>>>>
>>>> What about something like:
>>>> pg_isready; while [ $? -ne 2 ]; do sleep 1; pg_isready; done
>>>
>>> it is not enough - server is done in a moment, where can be started
>>> again - or when we can do safe copy of database data directory.
>>>
>>
>> I guess i am not completely understanding the case you are trying to
>> solve. Can you explain a bit further?
>
> We use puppets and due some simplification we cannot to use reload
> when configuration is changed. Our puppets has not enough intelligence
> to understand when is reload enough and when is restart necessary. So
> any change to configuration require restarting postgres. I don't know
> why "service restart" are not used. I believe so our puppet guru know
> it. It just do sequence STOP:START Now puppets are "smart" and able
> to wait for time, when server is ready. But there are missing simple
> test if server is really done and I see a error messages related to
> too early try to start. So some important feature can be verification
> so server is really done.
>
> We can do it with test on pid file now - and probably we will use it.
> But I see so this is similar use case (in opposite direction)
>

I guess I am still not clear why you can't do:

stop_pg_via_puppet
pg_isready
while [ $? -ne 2 ]
do
sleep 1
pg_isready
done
do_post_stop_things
start_pg_via_puppet

> Regards
>
> Pavel
>
>>
>>> Regards
>>>
>>> Pavel
>>>
>>>
>>>
>>>>
>>>> Perhaps with a counter to break out of the loop after some number of attempts.
>>>>
>>>>> Regards
>>>>>
>>>>> Pavel
>>>>>