[8.0] Kibana GET /api/stats breaking changes

[afharo]

Describe the enhancement:
Kibana is planning to remove the process info structure from its metrics (elastic/kibana#104124). This will likely affect Metricbeat's Kibana stats and status modules.

Describe a specific use case for the enhancement or feature:
The reasoning for removing that piece of info from the responses is detailed in the issue: elastic/kibana#104124.

TL;DR: For 8.0, we are planning on adding support to Kibana running multiple sub-processes in the same host. This means that process is unlikely to be meaningful anymore.

Related PRs:

• [core.metrics] Add support for multiple processes in ops metrics & stats API; deprecate process field kibana#109820
• [core.metrics] remove process field kibana#115200

[elasticmachine]

Pinging @elastic/stack-monitoring (Stack monitoring)

[matschaffer]

@sayden here's the json I was looking at testing for changes to https://github.com/elastic/beats/blob/master/metricbeat/module/kibana/stats/stats.go

7-15-1.json.zip
multi-process.json.zip

My thinking is that beats 8 could "upgrade" kibana <=7 from process: {} to processes: [{},...] and store that way.

Then in elastic/kibana#113149 I'll see if I can do the same thing via runtime fields so that the UI can plot old data in the new format and switch current graphs to be multi-line.

Given the title of this issue maybe we should check for /api/status changes as well. I haven't yet. Or maybe @mshustov or @Bamieh can confirm if anything on that API is changing as well.

[matschaffer]

Looks like all beats reads from /api/status is version.number anyway which doesn't appear to have changed between 7.15.1 and master. I'll update the title of this ticket. Feel free to change back if someone finds otherwise.