dnsdist: --config-check returns returncode 0 for non-existing config file

[christofchen]

• Program: dnsdist
• Issue type: Bug report

Short description

dnsdist returns 0 as result for a config check of an non-existing file.

I understand that an empty or nonexistent config file is syntactically valid for DNSDIST, but this is still a little bit surprising.
My expectation was that explicitly checking a file which cannot be read would result in a non-zero return code.

• Operating system: CentOS
• Software version: dnsdist 1.3.3
• Software source: PowerDNS repository

Steps to reproduce

dnsdist --check --config nonexistentfile; echo $?

Expected behaviour

Expectation: non-zero return code (because of "unable to read configuration from 'nonexistentfile').

Actual behaviour

$ dnsdist --check --config nonexistentfile; echo $?
Unable to read configuration from 'nonexistentfile'
Configuration 'nonexistentfile' OK!
0

Note the ZERO returncode.

[rgacogne]

Thank you for reporting this!
This is easy enough to fix (preliminary work in https://github.com/rgacogne/pdns/tree/dnsdist-check-config) but since we use --check-config in our systemd unit file, among other places, I wonder if that might break some setups where the default configuration file does not exist.