Incident description
Root Cause - Missing DNS record for dndrdc01.win.dante.org.uk
A change was implemented to fix the automatic renewal of the OV certificates, which triggered the HA Proxy service to restart. However, a missing DNS record for dndrdc01.win.dante.org.uk caused the Haproxy restart of the HA Proxy service to fail to restart (the change was carried out by IT .
The server dndrdc01 was decommissioned on 22 May 2020, but the record was cleaned up recently).
In order to fix the automatic renewal of the OV certificates, we renewed one of our existing certificates: *.dante.net
When OV renewal started working again, the new certificate was put in place and triggered a Haproxy service restart.
In the event of an unattended renewal, we would have experienced 4 hours of downtime (the renewal happens overnight, and we'd have discovered this problem the morning after. Forcing a manual renewal we have only had few minutes of downtime.
. We still don't know the exact time when this record was expunged, however, a similar issue was observed on another VM this morning. This needs to be investigated further with the help of IT.
A change request was not raised because this was considered a low-risk operation and was difficult to foresee the failure caused by the missing DNS record.
Incident SeverityIncident severity: CRITICAL
Data loss: NO
Timeline
...
Total downtime: 7 minutes
Proposed Solution
not available.
In future, even the low-risk operations on critical services such as HA Proxy should be carried out in the planned manner and out of business hours.
Identify the root cause of the communication gap regarding the missing DNS record with help from IT and take appropriate actionUsing a test certificate would not protect us. The way around, the real certificate would have been changed overnight, causing at least 4 hours of downtime.