graceful-takeover-auto switchover failed. when i set true for PreventCrossDataCenterMasterFailover.

[baijiu1]

I don't know if this is a bug. When I use one master and two slave architecture and set true for PreventCrossDataCenterMasterFailover, the instance selected for automatic switching is always the instance of another machine room, resulting in the failure of the whole switching

from orchestrator base version: 3.2.4

my architecture:

db.045.stg
+db.046.stg
+db.047.stg

When I use PreventCrossDataCenterMasterFailover set true, and DetectDataCenterQuery is :

select dc_vaild from meta.cluster where id = 1

Main configuration:

PreventCrossDataCenterMasterFailover: true
DataCenterPattern: ""

I issue this command:

orchestrator-client -c graceful-master-takeover-auto -alias test

return error:

PreventCrossRegionMasterFailover: will not promote server in Y when failed server in N

Status after switching:

db.045.stg
  +db.046.stg
    +db.047.stg

I Debug code, find this code and i fell this logic unreasonable:
function calls:

getGracefulMasterTakeoverDesignatedInstance->GetCandidateReplica->chooseCandidateReplica.

This result is caused by the error of the promotion instance returned here:

func chooseCandidateReplica(...) {
...golang
for _, replica := range replicas {
		replica := replica
		if isGenerallyValidAsCandidateReplica(replica) &&
			!IsBannedFromBeingCandidateReplica(replica) &&
			!IsSmallerMajorVersion(priorityMajorVersion, replica.MajorVersionString()) &&
			!IsSmallerBinlogFormat(priorityBinlogFormat, replica.Binlog_format) {
                        #######################################################
                        // Here should be added to the judgment of the data center
			// this is the one
			candidateReplica = replica
			break
		}
	}
...
}

And I have added judgment on the data center, so that I can switch in the test environment.

I think the automatic selection of instances should follow the configuration of the configuration file, otherwise the configuration will be meaningless.

Thanks!