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Using youki as a Kubernetes runtime

youki implements the OCI runtime spec, so it can be plugged into any Kubernetes cluster. Once youki is installed on each node and the node’s container runtime is configured to know about it, individual Pods can opt in via runtimeClassName: youki.

youki-deploy: ready-to-use installer for kind / containerd

The repository ships a small installer under tools/youki-deploy/ which automates install the youki binary on every node, and register it as a containerd runtime. It is composed of:

  • A Docker image that bundles the youki release binary and an install-youki.sh script.
  • A Kubernetes DaemonSet manifest that runs that image as a privileged pod on every node, mounts the host’s /usr/local/bin and /etc/containerd, copies the binary into place, patches /etc/containerd/config.toml, and restarts containerd.

It is currently exercised against kind (Kubernetes-in-Docker) but the manifests are Kubernetes resources and should apply to any containerd-based cluster.

Try it locally on kind

To stand up the cluster + DaemonSet:

$ just kind-deploy

To tear it down:

$ just clean-test-kind-deploy

See also Developer Documentation > Kubernetes test.

Using youki for your own Pods

Once the DaemonSet is installed, just add runtimeClassName: youki to the pod spec:

apiVersion: v1
kind: Pod
metadata:
  name: nginx-youki
spec:
  runtimeClassName: youki
  containers:
    - name: nginx
      image: nginx:1.27-alpine

Pods without runtimeClassName continue to use whatever the cluster’s default OCI runtime is (typically runc), so installing youki-deploy is non-disruptive for existing workloads.

Caveats

  • The installer modifies /usr/local/bin/youki and /etc/containerd/config.toml on the host. It does not currently uninstall on DaemonSet deletion - removing youki and the containerd config patch must be done manually.
  • The DaemonSet manifest references the installer image as youki-installer:latest, which is loaded into the local kind cluster by just kind-deploy. To deploy on a real cluster, build the image from tools/youki-deploy/Dockerfile and push it to a registry that your cluster nodes can pull from, then update the image field in tools/youki-deploy/youki-deploy.yaml.