We've discovered that our secondary is not authenticating properly after having the primary fail over to it. We have 2 MongoDB servers (v3.4) both properly setup in a replicaset:
mongo1:27017
mongo2:27017
And our connection string (for Node.js's MongoDB driver v2.2.19), is like this:
mongodb://username:password@mongo1,mongo2/db?replicaSet=rs0
Now, our primary failed and the secondary, mongo2 was elected primary. However, DB calls failed with 'not authorized' errors. So I took another look at the MongoDB docs:
mongodb://[username:password@]host1[:port1][,host2[:port2],...[,hostN[:portN]]][/[database][?options]]
It looks ambiguous, could the username:password be needed for each host? But that's weird because they are all replicated so the users should be the same, right?
I even tried it, using this connection string in the application:
mongodb://username:password@mongo1,username:password@mongo2/db?replicaSet=rs0
But that fails with: Error: Username with password containing an unescaped colon
The username and passwords are alphanumeric, so there seems to be a parsing problem with that style URI. But with the original, it's not authenticated properly. So these problems seem at odds with each other. I have verified in standalone mode that the user exists on both servers, and has the proper permissions. So I'm not sure where the problem lies. I found another very similar question with a different driver, but no answers :(
Well, I could never figure this out but updating the Node.js driver (v2.2.19 -> v2.2.33) seems to have fixed it. I didn't see anything relevant in the changelog and I'm not interested enough to compare diffs. C'est la vie de programming.