cfstras

Making TigerVNC work in macOS for kubevirt

This is especially useful for KubeVirt, which expects the command remote-viewer to exist when you run virtctl vnc $vm.

brew install vnc-viewer

cat <<EOF > /usr/local/bin/remote-viewer
#!/bin/bash
set -euo pipefail

cfstras

Converting a k3s control-plane to a worker node.

If you want to go from a 5-node-master to a 3-node-master cluster with less etcd quorum.

1. Drain the node: kubectl drain <node-name> --ignore-daemonsets --delete-emptydir-data --force --timeout=1m
2. Remove the node from the cluster: kubectl delete node <node-name>
   • Important: Remove from cluster first, otherwise the next step breaks the etcd quorum.
   • Also, you need to run etcdctl member remove $etcd_id first if this breaks the quorum.
   • Use etcdctl member list to find the $etcd_id.

cfstras

apiVersion: v1
automountServiceAccountToken: true
kind: ServiceAccount
metadata:
  name: mig-config-enforcer
  namespace: gpu-operator

---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole

cfstras

iperf3 between two kubernetes pods

A simple script to run an iperf3 test between two nodes in a kubernetes cluster.

Helpful to debug pod2pod communication issues in hybrid cloud clusters.

cfstras

(driver is outdated)

Note: the better solution would be to use the NVIDIA gpu-operator. They are exclusive -- either install the driver via gpu-operator with driver: {enabled: true} in the helm values -- or manually on your nodes like below:

# This worked on a VM with a RTX 50xx GPU attached (in proxmox, with PCIe Passthrough)

wget https://developer.download.nvidia.com/compute/cuda/repos/ubuntu$(grep DISTRIB_RELEASE /etc/lsb-release | cut -d'=' -f2 | tr -d '.')/x86_64/cuda-keyring_1.1-1_all.deb

cfstras

#!/bin/bash

set -euo pipefail

if [[ "$UID" -ne 0 ]]; then
	echo "This script needs to be executed as root"
	exit 1
fi

vendor_id="0x3000" # Valve

cfstras

tar -cv --zstd --options zstd:compression-level=22 --options zstd:threads=0 -f archive.tar.zstd files_to_compress/

Tested with bsdtar 3.5.3 (macOS 15.7.1)

cfstras

#!/bin/bash
set -euo pipefail

backup() {
  terraform state pull > state-$(gdate -Iseconds)
}

plan() {
  backup
  terraform plan -out=tfplan && terraform show -json tfplan | jq . > tfplan.json

cfstras

#!/bin/bash -euo pipefail

## Gives you a nice overview over the total timeseries cardinality of a prometheus endpoint.

curl -fsSL  http://localhost:9100/metrics | grep -v '^#' | cut -d'{' -f 1 | cut -d' ' -f 1 | sort | uniq -c | sort -gr

cfstras

public class DateTimeInsanityTests
{
    [Fact]
    public void YourDateTimeIsInsane()
    {
        var t = new DateTime();

        // Does not throw
        Console.WriteLine(new DateTimeOffset(t.ToUniversalTime()));