I've set up Prometheus' Alertmanager to, well, manage alerts from Prometheus. I've got the alerts coming in from Prometheus to Alertmanager, but there the story ends. The alerts never get sent on by Alertmanager to my email endpoint.
In order to figure out where exactly inside Alertmanager that the alerts end their journey I want to turn the log level from info to debug, but have been unable to figure out how. Even finding the log seems like a tough ask right now, its not in
journalctl -u alertmanager contains so little that it may be that there is another log somewhere.
The manual page for configuring Alertmanager does not mention debug level. I've looked through the source code for mentions of log and found that the setting should be named
log.level. Adding the following snippet to the configuration YAML didn't help either:
log: level: debug
as Alertmanager failed to start with a failure to parse its config file.