Find the resource-disk configuration owner before editing waagent on Ubuntu

Source facts

On Ubuntu Cloud Images where cloud-init manages the resource disk and swap, Microsoft’s documented waagent resource-disk format, filesystem, mount-point, swap-enable, and swap-size settings have no effect. Those images also default the agent’s provisioning setting to disabled when cloud-init handles provisioning. Elsewhere, waagent can create a swap file on the resource disk, but that disk is temporary and can be emptied during deprovisioning. Microsoft Learn.

Applicability

Use this check when a configuration file appears correct but an Ubuntu VM’s resource-disk layout or swap does not match it. Confirm the image’s actual provisioning arrangement rather than assuming every Linux VM uses the same owner for those tasks.

DSE recommendation

Identify which component owns resource-disk and swap configuration before proposing a setting change. Have the image maintainer review the effective cloud-init configuration and the intended disk use together. Remove ambiguity from the operating procedure by naming the supported configuration path for that image, while preserving a record of any existing setting that was mistakenly treated as authoritative.

Verification

Provision a disposable VM from the exact image version with the proposed configuration. Inspect the resulting mount and swap state and compare them with the intended values. Record the responsible component and sanitized evidence, not just the contents of waagent.conf. Investigate conflicting assumptions before rolling the image forward, and keep persistent application data outside any design that depends on this temporary disk surviving deprovisioning.

Official references

Microsoft Learn: Azure Linux VM Agent overview. Source reviewed September 9, 2026.