base64 and SASLprep: failed prohibited character check

I was trying something out on a minikube cluster the other day, and my python application could not connect to a mongo database that was deployed with helm. I had authentication enabled, the secret deployed in minikube and was greeted by the following error message:

SASLprep: failed prohibited character check

WTF? The password was definitely ascii printable characters. Could there be prohibited characters among the alphabet? I browsed through RFCs 4013 and 3454 but there was nothing I could immediately pinpoint there. However, this tweet by jpmens was circling my mind, and:

$ echo qwerty1234 | base64

$ printf qwerty1234 | base64

$ echo -n qwerty1234 | base64

Yes, the kubernetes secret had a \n attached to it. Because two things are hard in CS:
– naming things
– cache invalidation
– off by one errors