UPS Taint

Reads UPS details from a NUT server and automatically taint Kubernetes nodes with battery state to gracefully shed pods during a power outage. Intended to only augment and does not replace standard scripts to power down machines.

• Taints nodes as ups.spikedhand.com/status=on-battery:NoSchedule while running on battery power.
• Taints nodes as ups.spikedhand.com/status=low-battery:NoExecute if the UPS reports low battery.
• Taints nodes as ups.spikedhand.com/status=below-threshold:NoExecute if the UPS is below 50% battery.
• Removes the taint once the UPS is online again regardless of the charge level.

Why?

• My homelab has a small UPS.
• I want prioritize services that keep the network running well as long as possible because I work from home.
• Nova Scotia winter causes frequent short outages.
• Completely shutting down or draining a node for a usually short outage is overkill.
• Many home server applications are stateful and not designed for clusters. I'd prefer them to have shutdown well before a low battery requires them to be.

Deployment

• Ensure your NUT server is configured to be network accessible to the cluster.
• Label all nodes with the appropriate UPS name configured in NUT. IE: kubectl label node ${NODES} ups.spikedhand.com/name=${UPS_NAME}
• kubectl create ns ups-taint
• kubectl -n ups-taint create -f manifest/role.yml
• kubectl -n ups-taint create -f manifest/deployment.yml
• Create a secret named nut-server in the ups-taint namespace with username, password, and address. Alternatively update the deployment to provide the needed environment variables in another way.