There are a number of places where a shell command is constructed with
percent-placeholders (like %x). It's cumbersome to have to open-code
this several times. This factors out this logic into a separate
function. This also allows us to ensure consistency for and document
some subtle behaviors, such as what to do with unrecognized
placeholders.
The unified handling is now that incorrect and unknown placeholders
are an error, where previously in most cases they were skipped or
ignored. This affects the following settings:
- archive_cleanup_command
- archive_command
- recovery_end_command
- restore_command
- ssl_passphrase_command
The following settings are part of this refactoring but already had
stricter error handling and should be unchanged in their behavior:
- basebackup_to_shell.command
Reviewed-by: Nathan Bossart <nathandbossart@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/5238bbed-0b01-83a6-d4b2-7eb0562a054e%40enterprisedb.com
As a demonstration of the sort of thing that can be done by adding a
custom backup target, this defines a 'shell' target which executes a
command defined by the system administrator. The command is executed
once for each tar archive generate by the backup and once for the
backup manifest, if any. Each time the command is executed, it
receives the contents of th file for which it is executed via standard
input.
The configured command can use %f to refer to the name of the archive
(e.g. base.tar, $TABLESPACE_OID.tar, backup_manifest) and %d to refer
to the target detail (pg_basebackup --target shell:DETAIL). A target
detail is required if %d appears in the configured command and
forbidden if it does not.
Patch by me, reviewed by Abhijit Menon-Sen.
Discussion: http://postgr.es/m/CA+TgmoaqvdT-u3nt+_kkZ7bgDAyqDB0i-+XOMmr5JN2Rd37hxw@mail.gmail.com
Bruce Momjian
Robert Haas
Peter Eisentraut
Andres Freund
Tom Lane
Michael Paquier
Joe Conway