Currently changing resources (like dictionaries, synonym files etc...) of search
time analyzers is only possible by closing an index, changing the underlying
resource (e.g. synonym files) and then re-opening the index for the change to
take effect.
This PR adds a new API endpoint that allows triggering reloading of certain
analysis resources (currently token filters) that will then pick up changes in
underlying file resources. To achieve this we introduce a new type of custom
analyzer (ReloadableCustomAnalyzer) that uses a ReuseStrategy that allows
swapping out analysis components. Custom analyzers that contain filters that are
markes as "updateable" will automatically choose this implementation. This PR
also adds this capability to `synonym` token filters for use in search time
analyzers.
Relates to #29051
This commit adds a rest endpoint for freezing and unfreezing an index.
Among other cleanups mainly fixing an issue accessing package private APIs
from a plugin that got caught by integration tests this change also adds
documentation for frozen indices.
Note: frozen indices are marked as `beta` and available as a basic feature.
Relates to #34352
This commit is our first introduction to cross-cluster replication
docs. In this commit, we introduce the cross-cluster replication API
docs. We also add skelton docs for additional content that will be added
in a series of follow-up commits.