Systemd Dependency Cycle Issue with cloud-init.service on Azure Platform

This document (000021340) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server for SAP Applications 15 SP5
Microsoft Azure

Situation

An issue has been identified on Azure environments utilizing ephemeral disks, where an ordering cycle for cloud-init.service/stop is reported upon system shutdown. This problem is accompanied by error messages such as:

systemd[1]: cloud-init.service: Detected ordering cycle on cloud-init.service/stop:
systemd[1]: cloud-init.service: Breaking ordering cycle by deleting job cloud-init-local.service/stop
systemd[1]: cloud-init-local.service: Job cloud-init-local.service/stop deleted to break ordering cycle starting with cloud-init.service/stop

Resolution

It is recommended to manually remove the x-systemd.requires=wicked.service and _netdev options from the /etc/fstab entry for /dev/disk/cloud/azure_resource-part1.

Here is an example of the improved /etc/fstab entry:

/dev/disk/cloud/azure_resource-part1    /mnt    auto    defaults,nofail,comment=cloudconfig    0    2

By implementing this change, unnecessary dependencies during the mounting of the ephemeral disk can be avoided, thus preventing the ordering cycle during the system shutdown process.

Cause

Upon SLES VM deployment on Azure, the ephemeral disk is auto-configured as /dev/disk/cloud/azure_resource-part1 and mounted to /mnt as a block device, not a network resource, at startup through an entry in /etc/fstab:

/dev/disk/cloud/azure_resource-part1    /mnt    auto    defaults,nofail,x-systemd.requires=cloud-init.service,_netdev,comment=cloudconfig    0    2

This setup may creates a dependency loop within systemd, leading to the deletion of some unit stop jobs during shutdown, which can cause improper shutdowns and potential system inconsistencies.

Status

Reported to Engineering

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

Document ID:000021340
Creation Date: 30-Jan-2024
Modified Date:22-Feb-2024
- SUSE Linux Enterprise Server
- SUSE Linux Enterprise Server for SAP Applications
- SUSE Cloud Application Platform

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