Horton

Re: Possibility to disable `ALTER SYSTEM`

Peter Eisentraut <peter@eisentraut.org>

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From: Peter Eisentraut <peter@eisentraut.org>
To: Gabriele Bartolini <gabriele.bartolini@enterprisedb.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, "David G. Johnston" <david.g.johnston@gmail.com>, Magnus Hagander <magnus@hagander.net>, Robert Haas <robertmhaas@gmail.com>, Martín Marqués <martin.marques@gmail.com>, Isaac Morland <isaac.morland@gmail.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2024-02-06T14:10:27Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Add allow_alter_system GUC.

  2. Rename COMPAT_OPTIONS_CLIENT to COMPAT_OPTIONS_OTHER.

  3. Remove support for version-0 calling conventions.

On 31.01.24 11:16, Gabriele Bartolini wrote:
> I very much like the idea of a file in the data directory that also 
> controls the copy operations.
> 
> Just wanted to highlight though that in our operator we have already 
> applied the read-only postgresql.auto.conf trick to disable the system 
> (see 
> https://cloudnative-pg.io/documentation/current/postgresql_conf/#enabling-alter-system <https://cloudnative-pg.io/documentation/current/postgresql_conf/#enabling-alter-system>). However, having that file read-only triggered an issue when using pg_rewind to resync a former primary, as pg_rewind immediately bails out when a read-only file is encountered in the PGDATA (see https://github.com/cloudnative-pg/cloudnative-pg/issues/3698 <https://github.com/cloudnative-pg/cloudnative-pg/issues/3698>).
> 
> We might keep this in mind if we go down the path of the separate file.

How about ALTER SYSTEM is disabled if the file 
postgresql.auto.conf.disabled exists? This is somewhat similar to making 
the file read-only, but doesn't risk other tools breaking when they 
encounter such a file.  And it's more obvious and self-explaining.