K3s's Embedded Registry Mirror Was Supposed to Just Work. Then a New Edge Node Couldn't Pull Images
K3s's embedded registry mirror (Spegel) is supposed to work cluster-wide, but a newly added edge node alone failed to pull images. The cause: an undistributed registries.yaml, credential drift, and a known containerd 2.0 bug. Here's the correct distribution workflow for air-gapped operations.