How to Restore Hosts Removed from Monitoring in Mackerel

This article was originally published on bmf-tech.com.

Overview

This is a note on how to restore hosts that were mistakenly retired or unintentionally removed from monitoring in Mackerel.

Procedure

Simply restarting the mackerel-agent will not automatically restore the host, so you need to update the hostId assigned to the host.

service mackerel-agent stop
cd /var/lib/mackerel-agent
mv id /tmp/
service mackerel-agent start

Thoughts

I sometimes panic, so I want to be careful...