Update options flag for nginx-prometheus-exporter to new double dash format

[lbdemv]

Pull Request (PR) description

The nginx exporter logs the following deprecation warning after startup.

nginx-prometheus-exporter: the flag format is deprecated and will be removed in a future release, please use the new format: --nginx.scrape-uri

This PR intends to fix the deprecated flag format and use the current flag format with double dashes.

This Pull Request (PR) fixes the following issues

No issue opened so far.

[TheMeier]

@lbdemv do you know since when the "--" versions are supported?
https://github.com/nginxinc/nginx-prometheus-exporter/releases/tag/v1.0.0 ?

[lbdemv]

Sorry, I didn't actually check that. I just saw it and went on to fix the current warning...

Maybe I can dwell into that later today, if it is important.

[lbdemv]

As i see that, the deprecation change is made in nginx/nginx-prometheus-exporter#460
It was a fix for nginx/nginx-prometheus-exporter#447

The initial issue seem to be the change to kigpin in nginx/nginx-prometheus-exporter#420 which was flagged as a breaking change in the mentioned v1.0.0 changelog

[TheMeier]

I see. The default version in this module is currently 0.11.0 (https://github.com/voxpupuli/puppet-prometheus/blob/master/manifests/nginx_prometheus_exporter.pp#L66) so we need a version comparision here. Also there is a pending MR (#783) to update the version but that needs some work :(

[tuxmea]

We still need the version comparison.

[lbdemv]

@tuxmea I'm not sure if you are waiting for me to add anything? Or was this comment more like a memo for yourself?

[tuxmea]

memo

[TheMeier]

@lbdemv we need something like this:

if versioncmp($version, '1.0.0') >= 0 {
  $options = "--nginx.scrape-uri '${scrape_uri}' ${extra_options}"
} else {
  $options = "-nginx.scrape-uri '${scrape_uri}' ${extra_options}"
}

The tests need to be changed to check both cases. If you don't mind I could update your PR accordingly.

[lbdemv]

I don't mind at all. Go right ahead 😄