In Azure: Canonical Ubuntu Issue Impacted VMs and AKS
Issue:
Between 06:00 UTC on 30 Aug 2022 and 16:00 UTC on 31 Aug 2022, customers running Ubuntu 18.04 (bionic) Virtual Machines (VMs) who have Ubuntu unattended-upgrades enabled would have received systemd version 237-3ubuntu10.54 which would have resulted in Domain Name System (DNS) resolution errors. This issue was confined to this single Ubuntu version and impacted all regions in Public and Sovereign Clouds.
Affected System Version: 237-3ubuntu10.54
Need to check Affected Version with below command
dpkg-query --showformat='${Version}' --show systemdDue to this issue we cannot able to resolve any domain in Ubuntu 18.04 (bionic) like below screen shot
Customers running Ubuntu 18.04 (bionic) VMs who had Ubuntu Unattended-Upgrades enabled would have experienced the following:
- Loss of DNS resolution capabilities for resolving DNS queries impacting networking
- Newly created AKS pods stuck with an ImagePullBackoff due to an inability to resolve container registry hostnames specific to AKS
- Inability to access Azure Monitor, Application Insights, Log Analytics and Microsoft Sentinel log data
- Missed or delayed Log Search Alerts and Microsoft Sentinel Alert
Resolution:
Step 1: Take backup file /etc/systemd/resolved.conf
Step 2: Update FallbackDNS in the file /etc/systemd/resolved.conf
# FallbackDNS=168.63.129.16″
Step 3: Restart the services systemd-resolved
# systemctl restart systemd-resolved
