What

When the exporter tries to collect Nova metadata for instances, it always calls:

metadata, err := dom.GetMetadata(
    libvirt.DOMAIN_METADATA_ELEMENT,
    "http://openstack.org/xmlns/libvirt/nova/1.0",
    libvirt.DOMAIN_AFFECT_LIVE,
)

If the domain is not running, this fails with:

virError(Code=55, Domain=20, Message='Requested operation is not valid: domain is not running')

This causes noisy error logs like:

time=2025-09-25T08:42:35.323Z level=ERROR source=/go/src/app/collectors/domain_stats.go:458 msg="Failed to get Nova metadata" err="virError(Code=55, Domain=20, Message='Requested operation is not valid: domain is not running')"

Steps to Reproduce

1. Run libvirtd_exporter on a host with at least one shut off instance.
2. Observe the logs during metrics collection.

Expected behavior:
Exporter should gracefully handle inactive domains. Metadata should still be retrieved from the persistent config if the VM is not running, instead of logging errors.

Proposed fix

Fallback to DOMAIN_AFFECT_CONFIG if DOMAIN_AFFECT_LIVE fails.