[pgpool-hackers: 3988] Re: Proposal: using environment variables instead of script arguments

[anirudh.goel at cern.ch]

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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