Add SSL verification example for PostgreSQL

Before You Submit

• I have checked for existing issues and pull requests related to my suggestion.
• I have posted on the Nextcloud Community Help Forum if my suggestion is a troubleshooting scenario or I'm unsure about the solution.

Type of Suggestion

Suggesting an improvement

Relevant Documentation Links

https://docs.nextcloud.com/server/stable/admin_manual/configuration_database/linux_database_configuration.html

Summary

Add SSL verification example for PostgreSQL

Details

The manual presently only has SSL verification instructions for MySQL

'dbdriveroptions' => [
  \PDO::MYSQL_ATTR_SSL_KEY => '/../ssl-key.pem',
  \PDO::MYSQL_ATTR_SSL_CERT => '/../ssl-cert.pem',
  \PDO::MYSQL_ATTR_SSL_CA => '/../ca-cert.pem',
  \PDO::MYSQL_ATTR_SSL_VERIFY_SERVER_CERT => true,
],

It would be very useful (and make a lot of sense) if an equivalent instruction was provided for PostgreSQL users.

Additional Notes

Edit to add

Might be related https://github.com/nextcloud/server/pull/55256 needs to be documented ?

But I'm not at all familiar with the Nextcloud codebase, so someone else will need to verify and write the docs ? Maybe @Altahrim who submitted the merged patch could document it too ?

Edit to add more...

This desperately needs documenting by someone in the know !!!!!

A standalone PHP test:

<?php
$db = pg_connect("host=foo.example.com port=1234 dbname=example user=example password=secretsquirrel sslmode=verify-ca sslrootcert=test.pem");
echo pg_dbname();

Works fine. Connects instantly.

But neither this

 'dbname' => 'example',
  'dbhost' => 'foo.example.com',
  'dbport' => '1234',
  'dbtableprefix' => 'oc_',
  'dbuser' => 'example',
  'dbpassword' => 'example',
  'pgsql_ssl' => [
    'mode' => 'verify-ca',
    'cert' => '',
    'key' => '',
    'crl' => '',
    'rootcert' => 'test.pem',
  ],

It doesn't matter if I use the full patch to rootcert in the config.php. Nextcloud just hangs.

Removing pgsql_ssl, nextcloud connects fine.

I've no idea what's going on. 🤷

Start with the linked PostgreSQL SSL documentation request, the existing Linux database configuration page, and pull request #55256. Compare the standalone pg_connect example with the shown config.php pgsql_ssl settings and verify the correct behavior before documenting a working PostgreSQL SSL verification example.