## Summary
This PR adds a technical control to prevent incompatible mappings
changes. These include:
1. Removing mapped fields. For the foreseeable future we require that
teams only introduce new fields - in short: this avoids the "reindex"
step in our migrations.
2. Changing the type of a field. We leverage ES to determine whether a
given set of mappings can be applied "on top" of another. Similarly,
this avoids the "reindex" step in migrations.
The above checks depend on a snapshot of the mappings from `main`, these
are the "current" mappings and are extracted from plugin code. This PR
will bootstrap `main` with an initial set of mappings extracted from
plugins (bulk of new lines added).
## The new CLI
See the added `README.md` for details on how the CLI works.
## How will it work?
Any new PR that introduces compatible mappings changes will result in a
new snapshot being captured, then merged to main for other PRs to merge
and run the same checks against (currently committing new snapshots
happens in the CI check so there is no manual step of maintaining the
snapshot).
## Additional
We should consider combining this CI check with the existing check in
`src/core/server/integration_tests/saved_objects/migrations/check_registered_types.test.ts`.
Hopefully we can automate the check such that no manual review is needed
from Core, not sure how we might cover the hash of the non-mappings
related fields. We could consider narrowing the Jest test to exclude
mappings.
### Checklist
- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios
---------
Co-authored-by: kibanamachine <42973632+kibanamachine@users.noreply.github.com>
Co-authored-by: spalger <spencer@elastic.co>
