mysql_exporter_last_scrape_error 0 when mysql_up is 0

[guidoiaquinti]

mysql_exporter_last_scrape_error is reporting 0 (success) also when mysql_up is 0 (down).

This is a bit confusing if we rely on mysql_exporter_last_scrape_error to check for failures.

Steps to reproduce:

• start mysqld_exporter
• saturate the connection pool of the MySQL user used
• mysqld_exporter will report:

Jul 03 06:21:41 bash[14316]: time="2017-07-03T06:21:41-07:00" level=error msg="Error pinging mysqld: Error 1226: User 'monitoring_a' has exceeded the 'max_user_connections' resource (current value: 3)" source="mysqld_exporter.go:269"

while returning

mysql_exporter_last_scrape_error 0
mysql_up 0
mysql_exporter_scrapes_total 6716

[SuperQ]

Ahh, good catch. Looking at the code, I'm not sure this mysql_exporter_last_scrape_error does anything at all. 😬 I can't find any point in the exporter where we use it.

[siavashs]

I can look into this.
Should we set this metric to 1 even if one of the collectors fail? Or is it for general failures like connection issues with MySQL?

[SuperQ]

Any collector error should set this metric to 1.

[s4wet]

in my.cnf add line
bind-address = 127.0.0.1