Postgresql connection over SSL certificates

in your config/database.php file, edit the postgres config

'pgsql' => [
    ...
    'sslmode' => 'verify-ca',
    'options' => [
        // put here additional ssl options, like certs, etc.
    ],
    ...
],

have a read trhough pgsql docs for the options: https://www.postgresql.org/docs/9.6/libpq-ssl.html