prometheus
Consider mentioning potential auth problems in logs if no requests succeed
We get a fair few user support requests in that turn out to be auth problems. Giving a pointer in that direction in the log message mightn't be the worst idea.
fyi, I just found that setting security_level to AuthNoPriv instead of AuthPriv manifests itself as the "OID not increasing" error.
Running into this issue https://github.com/prometheus/snmp_exporter/pull/222 I faced a similar issue with community mismatch, just found it by patching snmp_exporter myself to show the community on Error. Not optimal.
Ran into a similar issue with nothing being returned by the exporter but it would scrape successfully. I had to open the device's SNMP server logs to figure out that I had a typo in a 64 char. SNMPv3 auth key... [two years later !!]
