We have a mongodb replica set with 3 nodes (db01-03) running as replica set "rs0".
When getting hosts info via MongoClient::getHosts(), the primary server SOMETIMES is being reported twice, once as part of the rs0, once standalone (so it seems?):
{
"db01.example.com:27017;rs0;...": {
"host": "db01.example.com",
"port": 27017,
"health": 1,
"state": 2,
"ping": 0,
"lastPing": 1475144757
},
"db02.example.com:27017;rs0;........": {
"host": "db02.example.com",
"port": 27017,
"health": 1,
"state": 1,
"ping": 0,
"lastPing": 1475144757
},
"db03.example.com:27017;rs0;.......": {
"host": "db03.example.com",
"port": 27017,
"health": 1,
"state": 2,
"ping": 0,
"lastPing": 1475144757
},
"db02.example.com:27017;-;.......": {
"host": "db02.example.com",
"port": 27017,
"health": 1,
"state": 1,
"ping": 0,
"lastPing": 1475143739
}
}
Why does this happen, is this intentional/accidental or something we should be concerned about?
Problem is, that our monitoring regularily compares "reported hosts" vs "expected hosts" and we receive alerts since 4 !== 3.
PS:Of course we could fix the alerts by comparing $actual<$expected; that is not the question, but:
Why is the primary sometimes shown twice?
