Add @Selector support to the configprops actuator endpoint

[philwebb]

It would be nice if you could limit the output of /actuator/configprops to a specific value in the same way that you can with the environment endpoint.

[onobc]

@philwebb I picked this up and wanted to run my thoughts on filtering by you before getting too much further. My plan is to:

Filter by prefix: /actuator/configprops?prefix=<config-props-prefix-goes-here>
Filter by config props simple classname: /actuator/configprops/<config-props-simple-classname-goes-here>

Examples:

• /actuator/configprops?prefix=spring.kafka
• /actuator/configprops/ServerProperties

[snicoll]

I think it's worth discussing how to filter the data. I don't know what Phil had in mind but if we want to do something similar to /env, I think the selector should be the id of the entity in the result. Unfortunately, this id isn't super easy to remember. I don't think we should be using SeverProperties, in particular, as you may have two cases with the same name.

Given that the prefix is easier to remember (and something that's easier to resonate than a class name), my vote would be the first option in your examples.

[onobc]

Unfortunately, this id isn't super easy to remember.

Yeh that is exactly what I ran into when I started w/ that as the filter.

in particular, as you may have two cases with the same name.

Yes that is true. In that case they would both show up as well w/ what prefix they are mapped to. I added this filter by asking myself what would I want to filter by. Prefix for sure. The properties class is the next thing I think of - KafkaProperties is one I end up looking at multiple times a day for example. Because I seem to find my way into those configprops classes in my editor I am familiar w/ the class name so it seemed like a good candidate. For me, they are both valuable.

Also, I have some screenshots to show the filtered results if that helps at all.

[philwebb]

Thanks for looking at this @Bono007. I added the issue as a note to myself so it's a bit light on details.

I think most users will probably want to filter on the property prefix, since that's the most user-facing value. I would suggest trying /actuator/configprops/<prefix> and then filtering the results so that only configuration properties starting with the given prefix are shown.

[onobc]

@snicoll @philwebb I will get the updates in w/in the next 24-48 hrs

[onobc]

@snicoll @philwebb I pivoted the merge request to filter only by prefix and also added the docs.

[philwebb]

Thanks @Bono007!

[wilkinsona]

Closing in favour of #24718.