Add Elasticsearch Health API

[Tim-Brooks]

Description

We intend to implement a new health reporting API which will return actionable health information about a Elasticsearch cluster. At a high level we intend the API to split Elasticsearch health into 8-10 components (coordination, backups, data, etc) with lower level indicators describing the current health of the components. Each indicator will have a health status (green/yellow/red). Each health indicator will be documented with actionable steps to fix indicators that are in a bad state.

Phase 1

We have identified the following 3 components will be introduced in the first phase.

• Cluster Coordination
• Data
• Snapshots

If possible, we will limit the first phase to extracting information from the cluster state. But future phases will require some type of coordination to ensure non-cluster state health data is in a single place to be gathered.

The specific development tasks are still being planned.

• [x] Add new API endpoint (#83119)
• [x] Add high level documentation for API (#83119)
• [ ] Add param functionality to support return just red, just red/yellow, all red/yellow/green indicators
• [x] Allow drilling down to a single component or indicator

[elasticmachine]

Pinging @elastic/es-distributed (Team:Distributed)

[elasticsearchmachine]

Pinging @elastic/es-data-management (Team:Data Management)