HAProxy Module improvements

[ruflin]

• Run make collect to make sure all files are up-to-date Update HAProxy module #2486
• Add tests to generate data.json files HAProxy module cleanup part one #2720
• Check that config files are according to standard (experimental disabled by default) Update HAProxy module #2486
  • See also https://github.com/elastic/beats/pull/2384/files#r76591317
• Review all haproxy fields for the naming convention
• Add CHANGELOG update Update HAProxy module #2486
• Improve source in docs: https://github.com/elastic/beats/pull/2486/files#r77964060 HAProxy docs updated #2929
• (The addresses specified in the configuration should be validated when the MetricSet is constructed. This allows -configtest to catch invalid URLs.)
• There are numerous errors being logged by the info MetricSet. Each individual value from the CSV is a string. Some of the strings are empty. When running the schema.Apply() an error happens because it's trying to convert an empty string to a int. If the haproxy.Stat fields were typed properly I think this would address the problem. HAProxy Module improvements #2485
• Document the supported version. HAProxy docs updated #2929
• Add a sample dashboard.

[andrewkroh]

(content moved to comment above)

[ruflin]

@andrewkroh I took your TODO's and also put them on the top so we have all in one place.

[hartfordfive]

@andrewkroh Regarding most of the errors regarding the HAProxy fields, I believe it's because some of the fields aren't present in each stat entry. How do you guys deal with fields that may not always have a value like in this case? That way I can keep that in mind for the next time I create a module.

[ruflin]

@hartfordfive For the fields that are optional, you can use the Optional flag. See for example here in apache status metricset: https://github.com/elastic/beats/blob/master/metricbeat/module/apache/status/data.go#L23

[ruflin]

@hartfordfive I did a first step of the cleanup here including making some fields optional: #2720

[andrewkroh]

The titles are duplicated:

And the description for the stat metricset says: "This is the info metricset of the module haproxy."

[Chadwiki]

^ I noticed this on the bottom nav.

[ruflin]

@andrewkroh @Chadwiki I addressed this in #2929

[hartfordfive]

@ruflin Thanks for making those changes. I haven't had much time to work on the haproxy or php-fpm module since my last commit. Hopefully I'll be able to continue working on the php-fpm module soon.

[ruflin]

@hartfordfive No worries. Looking forward to your future contributions.

[ruflin]

I think we are now mostly done with the cleanup. Only open point is creating dashboards and I kind of assuming during creating dashboards we will find some issues in the fields. @monicasarbu Interested to do the dashboards? ;-)

[ruflin]

Closing this even though we don't have the dashboards yet.