[V2] Upgrade Kubernetes version to 1.34 in demo and dev environments

[pingsutw]

Why are the changes needed?

The demo/sandbox environment was using Kubernetes 1.29 (k3s v1.29.0-k3s1), which is outdated. Upgrading to 1.34 brings security patches, performance improvements, and access to newer Kubernetes features.

What changes were proposed in this pull request?

• Bump k3s base image from v1.29.0-k3s1 to v1.34.6-k3s1 in docker/demo-bundled/Dockerfile.
• Bump kind node image from v1.26.0 to v1.34.0 in executor/DEVELOPMENT.md and dataproxy/DEVELOPMENT.md.
• Fix docker/demo-bundled/bin/k3d-entrypoint-cgroupv2.sh by replacing busybox xargs with the standalone xargs.

Why the cgroupv2 script change is needed

After bumping to rancher/k3s:v1.34.6-k3s1, make sandbox-run hung at Waiting for kubeconfig... because the container exited with code 1 before k3s ever started. Root cause:

1. The k3d entrypoint runs /bin/k3d-entrypoint-cgroupv2.sh before launching k3s. That script (copy-pasted from moby/moby's dind helper) calls busybox xargs -rn1 < /sys/fs/cgroup/cgroup.procs > /sys/fs/cgroup/init/cgroup.procs || : to evacuate processes from the root cgroup into /init so that writing to cgroup.subtree_control does not fail with EBUSY.
2. The busybox shipped inside rancher/k3s:v1.34.6-k3s1 was built without the xargs applet, so busybox xargs fails with xargs: applet not found. The || : swallows the error, so the script appears to continue.
3. But because the processes were never actually evacuated, the next line — sed ... > /sys/fs/cgroup/cgroup.subtree_control — fails with sed: write error (EBUSY). set -o errexit is in effect, so the entrypoint exits 1. k3s never starts, the kubeconfig is never written, and make sandbox-run waits forever.
4. The standalone /bin/xargs binary does exist in the k3s v1.34 image, so simply dropping the busybox prefix is enough — the cgroup evacuation then works and k3s boots normally.

Entrypoint log captured from the failing container before the fix:

[2026-04-10T06:55:06+00:00] Running k3d entrypoints...
[2026-04-10T06:55:06+00:00] Running /bin/k3d-entrypoint-cgroupv2.sh
[2026-04-10T06:55:06+00:00] [CgroupV2 Fix] Evacuating Root Cgroup ...
xargs: applet not found
sed: write error

How was this patch tested?

Rebuilt the demo image locally and ran make sandbox-run:

$ kubectl --context flyte-demo get nodes
NAME           STATUS   ROLES           AGE   VERSION
3494856c3ac2   Ready    control-plane   23s   v1.34.6+k3s1

$ kubectl --context flyte-demo get pods -n flyte
NAME                               READY   STATUS              RESTARTS   AGE
docker-registry-5b9f54d5d5-5wwpz   0/1     ContainerCreating   0          16s
flyte-binary-7b57dd88c6-dxcqg      0/1     Init:0/1            0          16s
flyte-console-69b86957f6-dpcd6     0/1     Running             0          16s
minio-6cb99cfc49-rbv5p             0/1     Running             0          16s

Cluster comes up on v1.34.6+k3s1, kubeconfig is written and merged into ~/.kube/config, and all demo workloads schedule normally.

Labels

• changed: Kubernetes version upgrade in demo and dev environments.

Check all the applicable boxes

• I updated the documentation accordingly.
• All new and existing tests passed.
• All commits are signed-off.

• main
  • Flyte 2 WIP #6583
    • [V2] Upgrade Kubernetes version to 1.34 in demo and dev environments 👈