Fix nil pointer exception in GenerateTokens (#6768)

* Fix nil pointer exception in GenerateTokens

Signed-off-by: Justin Jung <[email protected]>

* Changelog

Signed-off-by: Justin Jung <[email protected]>

---------

Signed-off-by: Justin Jung <[email protected]>

Author: justinjung04

CHANGELOG.md

@@ -45,6 +45,7 @@
 * [BUGFIX] Ingester: Avoid resharding for query when restart readonly ingesters. #6642
 * [BUGFIX] Query Frontend: Fix query frontend per `user` metrics clean up. #6698
 * [BUGFIX] Add `__markers__` tenant ID validation. #6761
+* [BUGFIX] Ring: Fix nil pointer exception when token is shared. #6768
 
 ## 1.19.0 2025-02-27
 

pkg/ring/token_generator.go

@@ -136,7 +136,11 @@ func (g *MinimizeSpreadTokenGenerator) GenerateTokens(ring *Desc, id, zone strin
 	for i := 1; i <= len(zonalTokens); i++ {
 		index := i % len(zonalTokens)
 		if tokenInstanceId, ok := usedTokens[zonalTokens[index]]; ok && tokenInstanceId != id {
-			instanceDistance := tokensPerInstanceWithDistance[tokenInstanceId]
+			instanceDistance, ok := tokensPerInstanceWithDistance[tokenInstanceId]
+			if !ok {
+				continue // Same token is shared to an ingester in different zone, skip
+			}
+
 			instanceDistance.tokens = append(instanceDistance.tokens, &tokenDistanceEntry{
 				token:    zonalTokens[index],
 				prev:     zonalTokens[i-1],