Override master promotion: apply post-unsuccessful processes

go/logic/topology_recovery.go

@@ -815,27 +815,36 @@ func checkAndRecoverDeadMaster(analysisEntry inst.ReplicationAnalysis, candidate
 	promotedReplica, lostReplicas, err := recoverDeadMaster(topologyRecovery, candidateInstanceKey, skipProcesses)
 	topologyRecovery.LostReplicas.AddInstances(lostReplicas)
 
-	// And this is the end; whether successful or not, we're done.
-	resolveRecovery(topologyRecovery, promotedReplica)
-	if promotedReplica != nil {
-		if config.Config.FailMasterPromotionIfSQLThreadNotUpToDate && !promotedReplica.SQLThreadUpToDate() {
-			message := fmt.Sprintf("RecoverDeadMaster: failed promotion. FailMasterPromotionIfSQLThreadNotUpToDate is set and promoted replica %+v 's sql thread is not up to date (relay logs still unapplied). Aborting promotion", promotedReplica.Key)
-			AuditTopologyRecovery(topologyRecovery, message)
-			return false, nil, log.Error(message)
+	overrideMasterPromotion := func() (*inst.Instance, error) {
+		if promotedReplica == nil {
+			// No promotion; nothing to override.
+			return promotedReplica, err
 		}
+		// Scenarios where we might cancel the promotion.
 		if satisfied, reason := MasterFailoverGeographicConstraintSatisfied(&analysisEntry, promotedReplica); !satisfied {
-			message := fmt.Sprintf("RecoverDeadMaster: failed %+v promotion; %s", promotedReplica.Key, reason)
-			AuditTopologyRecovery(topologyRecovery, message)
-			return false, nil, log.Error(message)
+			return nil, fmt.Errorf("RecoverDeadMaster: failed %+v promotion; %s", promotedReplica.Key, reason)
 		}
-		if config.Config.DelayMasterPromotionIfSQLThreadNotUpToDate {
-			AuditTopologyRecovery(topologyRecovery, fmt.Sprintf("Waiting to ensure the SQL thread catches up on %+v", promotedReplica.Key))
-			if _, err = inst.WaitForSQLThreadUpToDate(&promotedReplica.Key, 0, 0); err != nil {
-				return false, nil, err
+		if config.Config.FailMasterPromotionIfSQLThreadNotUpToDate && !promotedReplica.SQLThreadUpToDate() {
+			return nil, fmt.Errorf("RecoverDeadMaster: failed promotion. FailMasterPromotionIfSQLThreadNotUpToDate is set and promoted replica %+v 's sql thread is not up to date (relay logs still unapplied). Aborting promotion", promotedReplica.Key)
+		}
+		if config.Config.DelayMasterPromotionIfSQLThreadNotUpToDate && !promotedReplica.SQLThreadUpToDate() {
+			AuditTopologyRecovery(topologyRecovery, fmt.Sprintf("DelayMasterPromotionIfSQLThreadNotUpToDate: waiting for SQL thread on %+v", promotedReplica.Key))
+			if _, err := inst.WaitForSQLThreadUpToDate(&promotedReplica.Key, 0, 0); err != nil {
+				return nil, fmt.Errorf("DelayMasterPromotionIfSQLThreadNotUpToDate error: %+v", err)
 			}
-			AuditTopologyRecovery(topologyRecovery, fmt.Sprintf("SQL thread caught up on %+v", promotedReplica.Key))
+			AuditTopologyRecovery(topologyRecovery, fmt.Sprintf("DelayMasterPromotionIfSQLThreadNotUpToDate: SQL thread caught up on %+v", promotedReplica.Key))
 		}
-
+		// All seems well. No override done.
+		return promotedReplica, err
+	}
+	promotedReplica, err = overrideMasterPromotion()
+	if err != nil {
+		AuditTopologyRecovery(topologyRecovery, err.Error())
+	}
+	// And this is the end; whether successful or not, we're done.
+	resolveRecovery(topologyRecovery, promotedReplica)
+	// Now, see whether we are successful or not. From this point there's no going back.
+	if promotedReplica != nil {
 		// Success!
 		recoverDeadMasterSuccessCounter.Inc(1)
 		AuditTopologyRecovery(topologyRecovery, fmt.Sprintf("RecoverDeadMaster: successfully promoted %+v", promotedReplica.Key))