[v9.0.x] Alerting: Read group details before saving (#53808)

Co-authored-by: Gilles De Mey <gilles.de.mey@gmail.com>

public/app/features/alerting/unified/hooks/useCombinedRuleNamespaces.ts

@@ -115,7 +115,7 @@ export function sortRulesByName(rules: CombinedRule[]) {
   return rules.sort((a, b) => a.name.localeCompare(b.name));
 }
 
-function addRulerGroupsToCombinedNamespace(namespace: CombinedRuleNamespace, groups: RulerRuleGroupDTO[]): void {
+function addRulerGroupsToCombinedNamespace(namespace: CombinedRuleNamespace, groups: RulerRuleGroupDTO[] = []): void {
   namespace.groups = groups.map((group) => {
     const combinedGroup: CombinedRuleGroup = {
       name: group.name,

public/app/features/alerting/unified/utils/rulerClient.ts

@@ -157,16 +157,22 @@ export function getRulerClient(rulerConfig: RulerDataSourceConfig): RulerClient
       return addRuleToNamespaceAndGroup(namespace, groupSpec, newRule);
     }
 
-    const sameNamespace = existingRule.namespace === namespace;
-    const sameGroup = existingRule.group.name === values.group;
+    // we'll fetch the existing group again, someone might have updated it while we were editing a rule
+    const freshExisting = await findEditableRule(ruleId.fromRuleWithLocation(existingRule));
+    if (!freshExisting) {
+      throw new Error('Rule not found.');
+    }
+
+    const sameNamespace = freshExisting.namespace === namespace;
+    const sameGroup = freshExisting.group.name === values.group;
     const sameLocation = sameNamespace && sameGroup;
 
     if (sameLocation) {
       // we're update a rule in the same namespace and group
-      return updateGrafanaRule(existingRule, newRule, evaluateEvery);
+      return updateGrafanaRule(freshExisting, newRule, evaluateEvery);
     } else {
       // we're moving a rule to either a different group or namespace
-      return moveGrafanaRule(namespace, groupSpec, existingRule, newRule);
+      return moveGrafanaRule(namespace, groupSpec, freshExisting, newRule);
     }
   };