Replace usage of /elasticsearch/_msearch endpoint in tutorials

[joshdover]

In order to unblock removing legacy plugin support (#71927) we need to remove all usages of the /elasticsearch/_msearch endpoint. This can be replaced with a specific endpoint in the home plugin that provides only the needed functionality for the frontend.

kibana/src/plugins/home/public/application/components/tutorial/tutorial.js

Line 206 in 4eb455d

const response = await fetch(this.props.addBasePath('/elasticsearch/_msearch'), {

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)

[elasticmachine]

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

[ryankeairns]

@joshdover Can you provide any further detail on what exactly needs to happen? That will allows us to better determine when we could possibly fit this in.

Michael and Catherine are both working on high priority items for 7.10 (new header + search; home + landing pages), so I'm not sure if/when they'd be available.

[joshdover]

The backend endpoint /elasticsearch/_msearch is currently provided by the legacy elasticsearch plugin, which we need to remove in order to disable legacy plugins.

What needs to happen is that the code I linked to above needs to be calling a backend route that exists in the same plugin (home) and only exposes the minimum needed feature set to support whatever the UI does with that endpoint.

If we get to the point where this is the last blocker, the Platform team can help with this. Any investigation that could be done prior to Platform picking this up would be helpful. In particular, I think we just need to know what exactly this endpoint is being used for so we can provide an API that is narrower in scope rather than providing the entire ES search API.

[ryankeairns]

Thanks, that helps. I'll bring it up at our sync tomorrow.

[myasonik]

Did some digging into what _msearch does. What I found out:

On tutorial pages (such as at home#/tutorial/apm) there are various "check status" type buttons. Each tutorial sets their own config of what indexes to query and what the query config is.

The response is then used to to notify the user of the status (error, no data, has data). The exact data, how much of it, etc isn't ever used.

There seems to only be 8 uses of this. You can see all the configs here: https://github.com/elastic/kibana/search?l=TypeScript&q=esHitsCheck%3A+%7B