Unified Storage: Update index when indexqueueprocessor exists (#109351)

* Update readme

* When queue processor already exists, update the index on it in case it has been closed.

* Adds regression test.

pkg/storage/unified/README.md

@@ -296,6 +296,11 @@ docker in case you don't have one:
 docker run -d --name db -e "MYSQL_DATABASE=grafana" -e "MYSQL_USER=grafana" -e "MYSQL_PASSWORD=grafana" -e "MYSQL_ROOT_PASSWORD=root" -p 3306:3306 docker.io/bitnami/mysql:8.0.31
 ```
 
+or use our mysql docker block:
+```sh
+make devenv sources=mysql
+```
+
 ### 2. Create dedicated ini files for every service
 
 Example distributor ini file:
@@ -304,7 +309,7 @@ Example distributor ini file:
 * Bind and join `memberlist` on `127.0.0.1:7946` (default memberlist port)
 
 ```ini
-target = distributor
+target = search-server-distributor
 
 [server]
 http_port = 3000
@@ -404,6 +409,7 @@ path = grafana1.db
 [grafana-apiserver]
 address = 127.0.0.1:10000
 storage_type = unified-grpc
+search_server_address = 127.0.0.1:10000
 
 [server]
 protocol = http
@@ -443,9 +449,9 @@ Repeat for the other services.
 ./bin/grafana server target --config conf/storage-api-2.ini
 ./bin/grafana server target --config conf/storage-api-3.ini
 
-./bin/grafana server target --config conf/grafana1.ini
-./bin/grafana server target --config conf/grafana2.ini
-./bin/grafana server target --config conf/grafana3.ini
+./bin/grafana server --config conf/grafana1.ini
+./bin/grafana server --config conf/grafana2.ini
+./bin/grafana server --config conf/grafana3.ini
 ```
 
 etc

pkg/storage/unified/resource/search.go

@@ -943,6 +943,8 @@ func (s *searchSupport) getOrCreateIndexQueueProcessor(index ResourceIndex, nsr
 
 	key := fmt.Sprintf("%s/%s/%s", nsr.Namespace, nsr.Group, nsr.Resource)
 	if indexQueueProcessor, ok := s.indexQueueProcessors[key]; ok {
+		// index stored on existing processor may have been closed and rebuilt, so we need to update it
+		indexQueueProcessor.index = index
 		return indexQueueProcessor, nil
 	}
 

pkg/storage/unified/resource/search_test.go

@@ -2,6 +2,8 @@ package resource
 
 import (
 	"context"
+	"fmt"
+	"log/slog"
 	"sync"
 	"testing"
 	"time"
@@ -387,6 +389,49 @@ func TestSearchGetOrCreateIndexWithCancellation(t *testing.T) {
 	require.NoError(t, err)
 }
 
+func TestSearchWillUpdateIndexOnQueueProcessor(t *testing.T) {
+	// Regression test: Indexes were being closed when being rebuilt, but not updated on the queue processor. This was causing new events to
+	// be added to a closed index, resulting in an error and missing docs in the index.
+
+	// Create mock components
+	mockIndex1 := &MockResourceIndex{}
+	mockIndex2 := &MockResourceIndex{} // Different index to test replacement
+	mockBuilder := &MockDocumentBuilder{}
+
+	// Create searchSupport instance
+	s := &searchSupport{
+		log:                       slog.Default(),
+		indexQueueProcessors:      make(map[string]*indexQueueProcessor),
+		indexQueueProcessorsMutex: sync.Mutex{},
+		indexEventsChan:           make(chan *IndexEvent, 10),
+	}
+
+	nsr := NamespacedResource{
+		Namespace: "test-namespace",
+		Group:     "test-group",
+		Resource:  "test-resource",
+	}
+
+	// Pre-populate the processor to avoid the builders.get() call
+	key := fmt.Sprintf("%s/%s/%s", nsr.Namespace, nsr.Group, nsr.Resource)
+	processor1 := newIndexQueueProcessor(mockIndex1, nsr, 10, mockBuilder, s.indexEventsChan)
+	s.indexQueueProcessors[key] = processor1
+
+	// Verify initial state
+	require.Same(t, mockIndex1, processor1.index)
+
+	// Call getOrCreateIndexQueueProcessor with a different index
+	// This should return the existing processor but update its index
+	processor2, err := s.getOrCreateIndexQueueProcessor(mockIndex2, nsr)
+	require.NoError(t, err)
+	require.NotNil(t, processor2)
+
+	// Same processor instance, but index was replaced
+	require.Same(t, processor1, processor2, "Should return the same processor instance")
+	require.Same(t, mockIndex2, processor2.index, "Index should be replaced with mockIndex2")
+	require.Same(t, mockIndex2, processor1.index, "Original processor should have updated index")
+}
+
 type slowSearchBackendWithCache struct {
 	mockSearchBackend
 	wg sync.WaitGroup