[pgpool-hackers: 3991] Re: Proposal: using environment variables instead of script arguments

[Tatsuo Ishii]

Hi Anirudh,

Ok.
I am going to push this after minor releases are out (supoosed to be
out today).

> Hello Tatsuo
> 
> This looks great.
> 
> Thanks!
> 
> Anirudh
> On 4 Aug 2021, 8:11 AM +0530, Tatsuo Ishii <ishii at sraoss.co.jp>, wrote:
>> Hi Anirudh,
>>
>> I created a patch against master branch to add new parameter
>> "primary_host" to recovery_1st_stage_command (and
>> recovery_2ndt_stage_command. This is not necessary in practice but I
>> want to keep consistency).
>>
>> Suppose backend_hostname0 is the current primary node. Then
>> primary_host is replaced with backend_hostname0.
>>
>> Please let me what you think.
>>
>> > Hi Anirudh,
>> >
>> > > Hello Tatsuo
>> > >
>> > > Actually, there might be another way to use environment variables instead of script arguments for all commands.
>> > >
>> > > When the pgpool executes recovery_1st_stage (or recovery_2nd_stage) script on the primary, can it (automatically, in the background) run an additional script before that? Maybe that script can put all these variables in the primary node host「s environment?
>> > >
>> > > I know this is an additional step to add but it will invoke consistency in how these parameters are passed by pgpool, across scripts.
>> >
>> > > Does this make any sense?
>> >
>> > Well, that can be technically possible but it pollutes PostgreSQL
>> > process with environment variables. Also it is more complicated than
>> > just adding a new parameter to the function. It seems it is not worth
>> > the trouble.
>> >
>> > > Cheers!
>> > >
>> > > Anirudh
>> > > On 15 Jul 2021, 12:24 PM +0530, Tatsuo Ishii <ishii at sraoss.co.jp>, wrote:
>> > > > > Hello Tatsuo
>> > > > > > Unfortunately recovery commands are executed on the PostgreSQL primary
>> > > > > > node by calling pgpool_recovery extension. There's no way to pass
>> > > > > > environment variables from pgpool side. So my proposal is not applied
>> > > > > > to below commands.
>> > > > >
>> > > > > Fair point. Then as per our other discussion, to pass PRIMARY_NODE_HOST to the recovery_1st_stage script, can we do it by passing it as an argument to the command?
>> > > >
>> > > > Yeah, it seems it's the only way.
>> > > >
>> > > > Best regards,
>> > > > --
>> > > > Tatsuo Ishii
>> > > > SRA OSS, Inc. Japan
>> > > > English: http://www.sraoss.co.jp/index_en.php
>> > > > Japanese:http://www.sraoss.co.jp
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