[META] Change Inventory to consume new services exposed by EEM

[cauemarcondes]

Inventory changes:

• Get entity types API (GET /internal/inventory/entities/types)

Description: This API fetches all entity types available
Return type: string[]
Replace it by: GET /internal/entities/v2/definitions/types #201470
Where it's/could be used:

• It's used to fill up the Entity types filter input in the unified search bar.
• It could be used to render the group by page.

Notes:

• Kuery filters is under discussion: https://github.com/elastic/elastic-entity-model/issues/206
• The API currently doesn't return the total number of entities. https://github.com/elastic/elastic-entity-model/issues/208

---

• Group by API (GET /internal/inventory/entities/group_by/{field})

_Description: Group entities by the provided field (currently only by entity.type is supported).
Action: This API can be deleted.
Where it's/could be used:

• It's used to create the group by page.

---

• Get all entities (GET /internal/inventory/entities)

_Description: Fetches all entities by a given entity type.
Return type: InventoryEntity
Replace it by:

POST kbn:/internal/entities/v2/_search
{
    "type": "service",
    "limit": 500,
    "metadata_fields": ["data_stream.type"]
}

Notes:

• The new API fetches last 5m of data, we can change it by adding a start and end properties. (Should we add a date picker on the ui?)
• The API should return the same object as the current api.
• The current API sorts entities by entity.last_seen_timestamp field, this should still be the same.
• The user can change the sorting field or direction, we must pass it to the new API. https://github.com/elastic/elastic-entity-model/issues/205
• Pagination should still be handled in the client side, 500 entities will be returned displaying 20 entities per page.
• Alerts count will still be fetched on our side using the data returned by the new API request.
• Links to solutions(apm/infra...)/dashboard will still be handled in the UI.
• Kuery filters is under discussion: https://github.com/elastic/elastic-entity-model/issues/206
• Use the entity.display_name field or fallback to entity.id field it the first is not available: https://github.com/elastic/elastic-entity-model/issues/207

---

• Adhoc data view

We need to provide a dataview to the KQL bar and to the "Open in discover" button. We can create it ourselves by calling this API GET kibana_entity_definitions/_search and get the field index_patterns. Or EEM could provide it for us. @simianhacker / @elastic/obs-entities

---

APM changes:

• APM fetches the datastream_type from a given service name on the entities latest index. We'll need to update it to call the new API instead:
  API: GET /internal/apm/entities/services/{serviceName}/summary

POST kbn:/internal/entities/v2/_search
{
    "type": "service",
    "limit": 1,
    "metadata_fields": ["data_stream.type"],
    "filters": ["service.name == \"service-9\"", "service.environment == \"Synthtrace: other_bucket_group development\""]
}

• Delete GET /internal/apm/entities/services.
• /link-to/entity/{serviceName} route:
  This link is used to link service names shown on logs explorer and discover, It also uses the summary API GET /internal/apm/entities/services/{serviceName}/summary, and needs to be tested.

---

Hosts changes:

• Like APM, the Hosts page also has a summary API to fetch the datastream_type from a given entity type (host or container) and id.
  API: /api/infra/entities/{entityType}/{entityId}/summary

POST kbn:/internal/entities/v2/_search
{
    "type": "host",
    "limit": 1,
    "metadata_fields": ["data_stream.type"],
    "filters": ["host.name == \"k8s-standalone-549ccd-c9nrv\""]
}

POST kbn:/internal/entities/v2/_search
{
    "type": "container",
    "limit": 1,
    "metadata_fields": ["data_stream.type"],
    "filters": ["container.id == \"d8e5efb1823f6dade09f6f2e57fd4e8cd67e76b782ecd18b6398d80445454ee3\""]
}

[elasticmachine]

Pinging @elastic/obs-ux-infra_services-team (Team:obs-ux-infra_services)

[cauemarcondes]

Broke this down on small issues:
#202295
#202296
#202298
#202300
#202299