This PR adds deprecation warnings when accessing System Indices via the REST layer. At this time, these warnings are only enabled for Snapshot builds by default, to allow projects external to Elasticsearch additional time to adjust their access patterns.
Deprecation warnings will be triggered by all REST requests which access registered System Indices, except for purpose-specific APIs which access System Indices as an implementation detail a few specific APIs which will continue to allow access to system indices by default:
- `GET _cluster/health`
- `GET {index}/_recovery`
- `GET _cluster/allocation/explain`
- `GET _cluster/state`
- `POST _cluster/reroute`
- `GET {index}/_stats`
- `GET {index}/_segments`
- `GET {index}/_shard_stores`
- `GET _cat/[indices,aliases,health,recovery,shards,segments]`
Deprecation warnings for accessing system indices take the form:
```
this request accesses system indices: [.some_system_index], but in a future major version, direct access to system indices will be prevented by default
```
For 1/2 the plugins in x-pack, the integTest
task is now a no-op and all of the tests are now executed via a test,
yamlRestTest, javaRestTest, or internalClusterTest.
This includes the following projects:
security, spatial, stack, transform, vecotrs, voting-only-node, and watcher.
A few of the more specialized qa projects within these plugins
have not been changed with this PR due to additional complexity which should
be addressed separately.
related: #60630
related: #56841
related: #59939
related: #55896