Needs to be backported?

Backport status

* SOLR-16273: Improve the performance of the Prometheus Metric Exporter scraping metrics (Matthew Biscocho via David Smiley & Christine Poerschke)

* SOLR-16445: Leader message should only be sent when there is more than one (NRT+Tlog) replica (Hitesh Khamesra, noble via Ishan Chattopadhyaya)

* SOLR-14853: Security: Converted enableRemoteStreaming and enableStreamBody solrconfig options into system properties and env vars. Attempts to set them the old way are no-op and log a warning. (David Smiley, janhoy, Ishan Chattopadhyaya)

* SOLR-16855: Solr now provides a MigrateReplicas API at `POST /api/cluster/replicas/migrate` (v2), to move replicas off of a given set of nodes. This extends the functionality of the existing ReplaceNode API. (Houston Putman)

* SOLR-16806: Solr now provides a BalanceReplicas API at `POST /api/cluster/replicas/balance` (v2), to spread replicas across a given set of nodes. No v1 API is available. (Houston Putman, Tomás Fernández Löbbe, Jason Gerlowski, Radu Gheorghe)

* SOLR-14749: Provide a clean API for cluster-level event processing. Improve support for arbitrary container-level plugins. Add ClusterSingleton support for plugins that require only one active instance in the cluster. (ab, noble)

* SOLR-16392: A number of v2 "replica" endpoints have been updated to be more REST-ful, and hopefully, intuitive. ADDREPLICAPROP is now `PUT /api/collections/$coll/shards/$shard/replicas/$rep/properties/$prop {"value": $val}` DELETEREPLICAPROP is now `DELETE /api/collections/$coll/shards/$shard/replicas/$rep/properties/$prop`

* SOLR-15478: A v2 equivalent of CLUSTERSTATUS command is now available at `GET /api/cluster`. Collection listing, previously at this path, can still be accessed at `GET /api/collections`. (Joshua Ouma via Jason Gerlowski)

* SOLR-15479: A v2 equivalent of the RENAME command is now available at `POST /api/collections/collName/rename`. (Anakhe Ajayi via Jason Gerlowski)

* SOLR-11028: A v2 equivalent of the `/admin/collections?action= REPLACE` command is now available at `POST /api/cluster/nodes/nodeName/replace`. (Joshua Ouma via Jason Gerlowski)

* SOLR-11029: A v2 equivalent of the `/admin/collections?action=DELETENODE` command is now available at `POST /api/cluster/nodes/nodeName/clear`. (Bence Szabo via Jason Gerlowski)

* SOLR-16462: v2 equivalents of the "Core Admin" `LISTSNAPSHOT`, `CREATESNAPSHOT`, and `DELETESNAPSHOT` commands are now available at `GET /api/cores/coreName/snapshots`, `POST /api/cores/coreName/snapshots/snapshotName`, and `DELETE /api/cores/coreName/snapshots/snapshotName`, respectively (John Durham via Jason Gerlowski)

* SOLR-16488: The paths of the v2 "ZooKeeper read" APIs have been tweaked slightly to be more intuitive. "get node data" is now available at `GET /api/cluster/zookeeper/data/<path>`, and "list node children" is now available at `GET /api/cluster/zookeeper/children/<path>` (Jason Gerlowski, Joshua Ouma)

* SOLR-16393: The path of the v2 "list alias" API has been tweaked slightly to be more intuitive, and is now available at `GET /api/aliases`. It is also now possible to request information about a specific alias at `GET /api/aliases/<aliasName>`. (Alex Deparvu via Jason Gerlowski)

* SOLR-16393: The path of the v2 "delete alias" API has been tweaked slightly to be more intuitive, and is now available at `DELETE /api/aliases/aliasName`. (Jason Gerlowski)

* SOLR-16393: Solr's v2 "aliasprop" CRUD APIs have been tweaked slightly to be more intuitive. Alias property modification is now available at `PUT /api/aliases/aliasName/properties` (for bulk modification) and `PUT /api/aliases/aliasName/properties/propName` (for single property updates). Additionally new APIs have been added for listing properties (`GET /api/aliases/aliasName/properties`), fetching single property values (`GET /api/aliases/aliasName/properties/propName`), and property deletion (`DELETE /api/aliases/aliasName/properties/propName`). (Alex Deparvu via Jason Gerlowski)

* SOLR-16391: The path of the v2 "collprop" API has been tweaked slightly to be more intuitive. Endpoints are now available under the `PUT` and `DELETE` verbs at `/api/collections/collName/properties/propName` depending on whether the property is being upserted or deleted. (Jason Gerlowski)

* SOLR-16394: The path of the v2 "collection backup" API has been tweaked slightly to be more intuitive, and is now available at `POST /api/collections/backups/backupName/versions`. (Jason Gerlowski)

* SOLR-16458: Solr's v2 "logging" APIs have been tweaked slightly to be more intuitive. The single v2 endpoint that existing previously (GET /api/node/logging) has been split into several different APIs. Logger levels can be fetched or modified at `GET /api/node/logging/levels` and `PUT /api/node/logging/levels`, respectively. Log messages can be returned from a "listener" at `GET /api/node/logging/messages`. And the threshold for the log "listener" can be modified with `PUT /api/node/logging/messages/threshold`. (Jason Gerlowski, Calvince Otieno)

* SOLR-15737: Solr's collection-level "snapshot" APIs now have v2 equivalents. Snapshots can be created at `POST /api/collections/collName/snapshots/snapshotName`, listed at `GET /api/collections/collName/snapshots`, and deleted at `DELETE /api/collections/collName/snapshots/snapshotName`. (John Durham via Jason Gerlowski)

* SOLR-16391: Solr's v2 "create collection" API has been tweaked slightly to be more intuitive. It remains available under `POST /api/collections`, but the top level "create" command-name key has been removed. (Jason Gerlowski)

* SOLR-16393: The v2 "create alias" API has been tweaked to be more intuitive. The format of the request body has changed slightly: the "create-alias" command specifier has been removed, the "name" field for individual routers has been renamed to "type", and the routers themselves are now always grouped into a list. Additionally the v2 API has moved to the new path `POST /api/aliases`. (Jason Gerlowski)

* SOLR-16394: The v2 "restore" API has been tweaked to be more intuitive. The top-level "restore-collection" command specifier has been removed, and the API now lives at the new path `POST /api/backups/backupName/restore`. (Jason Gerlowski)

* SOLR-16392: The v2 deletereplica API has been tweaked to be more intuitive: single replicas deletion now uses `DELETE /api/collections/cName/shards/sName/replicas/rName`, deletion of multiple relicas in a single shard uses `DELETE /api/collections/cName/shards/sName/replicas?count=123`, and deletion of multiple replicas from all shards now uses `PUT /api/collections/cName/scale {"count": 123"}` (Jason Gerlowski)

* SOLR-16394: The v2 list and delete (collection) backup APIs have been tweaked to be more intuitive: backup listing now uses `GET /api/backups/bName/versions`, backup deletion by ID now uses `DELETE /api/backups/bName/versions/1`, backup deletion by recency now uses `DELETE /api/backups/bName/versions?retainLatest=3`, and index-file "garbage collection" now uses `PUT /api/backups/backupName/purgeUnused` (Jason Gerlowski)

* SOLR-16470: `/coreName/replication?commit=indexversion` now has a v2 equivalent, available at `GET /api/cores/coreName/replication/indexversion` (Matthew Biscocho via Jason Gerlowski)

* SOLR-16392: The v2 "create shard" API has been tweaked to be more intuitive, by removing the top-level "create" command specifier. The rest of the API remains unchanged. (Jason Gerlowski)

* SOLR-16392: The v2 "add-replica" API has been tweaked to be more intuitive, by removing the top-level command specifier and changing the path. The v2 functionality can now be accessed at: `POST /api/collections/cName/shards/sName/replicas {...}` (Jason Gerlowski)

* SOLR-16398: Several v2 "command" APIs have been tweaked to be more intuitive. "FORCELEADER" is now available at `POST /api/collections/cName/shards/sName/force-leader`, "RELOAD" is now available at `POST /api/collections/cName/reload`, "SYNCSHARD" is now available at `POST /api/collections/cName/shards/sName/sync-shard`, and "RENAME" is now available at `POST /api/collections/cName/rename`. (Jason Gerlowski)

* SOLR-16398: The v2 "balance-shard-unique" API has been tweaked to be more intuitive, by removing the top-level command specifier from the request body, and changing the path. The v2 functionality can now be accessed at: `POST /api/collections/cName/balance-shard-unique {...}` (Jason Gerlowski)

* SOLR-16470: `/coreName/replication?command=filelist` now has a v2 equivalent, available at `GET /api/cores/coreName/replication/files?generation=123` (Matthew Biscocho via Jason Gerlowski)

* SOLR-16397: Reload core v2 endpoints have been updated to be more REST-ful. RELOAD is now available at `POST /api/cores/coreName/reload` (Sanjay Dutt via Jason Gerlowski)

* SOLR-16490: `/admin/cores?action=backupcore` now has a v2 equivalent, available at `GET /api/cores/coreName/backups` (Sanjay Dutt via Jason Gerlowski)

* SOLR-16490: The semi-internal `/admin/cores?action=restorecore` API now has a v2 equivalent, available at `POST /api/cores/coreName/restore {...}` (Sayanti Dey via Jason Gerlowski)

* SOLR-16825: Solr now offers `SolrRequest` implementations for a subset of its v2 APIs. These implementations are experimental and should be used with caution, but may be preferable to their v1 counterparts in some circumstances as they are generated and more likely to remain up-to-date with future API changes. (Jason Gerlowski, David Smiley, Houston Putman)

* SOLR-16461: `/solr/coreName/replication?command=backup` now has a v2 equivalent, available at `/api/cores/coreName/replication/backups` (Sanjay Dutt, Jason Gerlowski, Alex Deparvu)

* SOLR-15276: V2 API call to look up async request status restful style of "/cluster/command-status/1000" instead of "/cluster/command-status?requestid=1000". (Eric Pugh)

* SOLR-13396: Add property to control the deletion of unknown cores. The default setting is to not delete unknown cores. This is a change to behaviour introduced in Solr 7.3.1 by SOLR-12066. To continue using the previous behaviour, Solr can be started with the system property `solr.deleteUnknownCores` set to `true`. (Colvin Cowie, janhoy)

* SOLR-14789: Migrate docker image creation from docker-solr repo to solr/docker. (Houston Putman, Martijn Koster, Tim Potter, David Smiley, janhoy, Mike Drob)

* SOLR-15949: Docker: the official image now uses Java 17 provided by Eclipse Temurin. Formerly it was Java 11 from OpenJDK. (janhoy, David Smiley)

* SOLR-14001: Docker: Removed /var/solr initialization from the Dockerfile; depend on init_var_solr.sh instead. This leads to more consistent behavior no matter how /var/solr is mounted. * init_var_solr.sh is now invoked by docker-entrypoint.sh; not in a bunch of other places. * as before, you can set NO_INIT_VAR_SOLR=1 to short-circuit this. * init_var_solr.sh no longer echo's anything. For verbosity, set VERBOSE=yes. (David Smiley)

Deprecation Removals

Deprecation Removals

* SOLR-14272: Remove autoReplicaFailoverBadNodeExpiration and autoReplicaFailoverWorkLoopDelay for 9.0 as it was deprecated in 7.1 (Anshum Gupta)

Deprecation Removals

Deprecation Removals

Deprecation Removals

Deprecation Removals

* SOLR-14035: Remove deprecated preferLocalShards=true support in favour of the shards.preference=replica.location:local alternative. (Alex Bulygin via Christine Poerschke)

Deprecation Removals

Deprecation Removals

Deprecation Removals

* SOLR-13893: Remove support to read BlobRepository's max jar size from deprecated `runtme.lib.size` system property (Erick Erickson, Kesharee Nandan Vishwakarma, Munendra S N)

Deprecation Removals

Deprecation Removals

* SOLR-12823: Remove /clusterstate.json support, including support for collections created with stateFormat=1, as well as support for Collection API MIGRATESTATEFORMAT action and support for the legacyCloud flag (Ilan Ginzburg).

Deprecation Removals

Deprecation Removals

Deprecation Removals

Deprecation Removals

Deprecation Removals

* SOLR-15341: Remove indexHeapUsageBytes info from /admin/segments and /admin/luke because it's no longer available in Lucene -- LUCENE-9387. (janhoy, David Smiley)

Deprecation Removals

Deprecation Removals

Deprecation Removals

Deprecation Removals

* SOLR-12336: Remove Filter, SolrFilter and SolrConstantScoreQuery. Filter no longer has a need to exist due to multiple JIRA issues, implemented by a number of issues. With Filter going away, there is no longer need for SolrConstantScoreQuery. (Collins Abanda, Mike Drob, Tim Potter, David Smiley, Michael Gibney)

Deprecation Removals

Dependency Upgrades

Dependency Upgrades

SOLR-16432, SOLR-16508

Dependency Upgrades

Dependency Upgrades

Dependency Upgrades