Command to validate a postgresql configuration file?

Question

I am generating postgresql configuration files via ansible, and putting them in /etc/postgresql/XX/main/conf.d/whatever.conf. I accidentally made a syntax error and broke my postgresql, requiring manual fixing.

Is there any postgresql command to validate that a file is a valid postgresql.conf file?

sudoers files can be validates with /usr/sbin/visudo -cf path/to/file. Is there anything for postgresql?

I'm currently running Ubuntu 18.04 & 20.04, with PostgreSQL 10, 12 etc (yes several different versions).

Answer 1

Yes.

At least as of version 10 there is a mechanism to check the config file from within postgres.

This is the result of adding a fubar to my config file, didn't reload it.

postgres=# select sourcefile, name, sourceline, error from 
           pg_file_settings where error is not null;
               sourcefile                | name | sourceline |    error
-----------------------------------------+------+------------+--------------
 /etc/postgresql/12/main/postgresql.conf |      |         33 | syntax error
(1 row)

Docs will be: https://www.postgresql.org/docs/10/view-pg-file-settings.html, also, you might be interested in https://www.postgresql.org/docs/10/view-pg-hba-file-rules.html

Answer 2

The only program that I know is postgres, the database server.

I have two approaches to deal with that problem:

• After you edit postgresql.conf and reload, examine the PostgreSQL log file. If there was a problem, you will see that in the log, an the server will keep running with the previous configuration (no outage). Fix the file and try again until it the reload is successful.

• Use ALTER SYSTEM rather than postgresql.conf to change configuration parameters. That works just as well, and ALTER SYSTEM will catch most of the possible syntax errors. Of course, you should still look at the PostgreSQL log after reloading.

As an alternative to checking the log file, you may use the pg_file_settings view as described in the other answer.

Answer 3

With the command postgres (see man postgres for details) you can query a config parameter and if something in one of the config files is invalid, it shows an error.

Example Postgresql version 12 on Debian as user postgres:

$ /usr/lib/postgresql/12/bin/postgres --config-file=/etc/postgresql/12/main/postgresql.conf -C data_directory
/var/lib/postgresql/13/main
$ echo $?
0

now with an error in the config:

$ /usr/lib/postgresql/12/bin/postgres --config-file=/etc/postgresql/12/main/postgresql.conf -C data_directory
2023-03-31 11:15:22.550 [5041] LOG:  unrecognized configuration parameter "unknown" in file "/etc/postgresql/12/main/conf.d/example_error.conf" line 2
2023-03-31 11:15:22.550 [5041] FATAL:  configuration file "/etc/postgresql/12/main/conf.d/example_error.conf" contains errors
$ echo $?
1