Support filter_path parameter for Kibana APIs just like the Elasticsearch APIs do

[bczifra]

Describe the feature:
Elasticsearch supports a filter_path parameter that can be used to reduce the response returned by Elasticsearch. It would be helpful if Kibana also supported such a property.

Describe a specific use case for the feature:
Retrieving only a subset of the fields returned by a given API. For example, the Get agent policies returns quite a bit of data. If the user only wanted to return the id and the name, then using the filter_path option they could specify: GET /agent_policies?filter_path=items.*.id,items.*.name.

Related: #144640

[elasticmachine]

Pinging @elastic/kibana-security (Team:Security)

[elasticmachine]

Pinging @elastic/kibana-core (Team:Core)

[elasticmachine]

Pinging @elastic/fleet (Team:Fleet)

[pgayvallet]

This is not something that can be done globally at core's level for all API. I'll tentatively assign to fleet given they own the endpoint in the description here.

[DBchmnn]

Are there any news regarding this topic? Will this functionality be implemented in a future version?
And is there any other current possibility to limit the response of Kibana API?

[kpollich]

Unfortunately this isn't something we're actively considering supporting in the Fleet API, and without an ability to implement at the global level I don't think it's likely to become a priority for other APIs in Kibana either. Our recommendation today would be to handle filtering unneeded fields as part of your data fetching logic however you're consuming Kibana's APIs. If payload size is a concern, please ensure server.compression.enabled is set to true in your kibana.yml configuration.