## Runtime {#runtime}...

cgroupDriver value in the KubeletConfiguration is now always set to "systemd" unless the user is explicit about it. This requires existing machine setups to configure the container runtime to use the "systemd" driver. Documentation on this topic can be found here: https://kubernetes.io/docs/setup/production-environment/container-runtimes/. When upgrading existing clusters / nodes using "kubeadm upgrade" the old cgroupDriver value is preserved, but in 1.22 this change will also apply to "upgrade". For more...

### **Node Components**
#### Container Runtime Interface

* Kubelet now proxies container streaming between apiserver and container runtime. The connection between kubelet and apiserver is authenticated. Container runtime should change streaming server to serve on localhost, to make the connection between kubelet and container runtime local. ([#64006](https://github.com/kubernetes/kubernetes/pull/64006), [@Random-Liu](https://github.com/Random-Liu))

From v1.24 onwards, you will need to either use one of the other [supported runtimes](https://kubernetes.io/docs/setup/production-environment/container-runtimes/) (such as containerd or CRI-O)
or use cri-dockerd if you are relying on Docker Engine as your container runtime.
For more information about ensuring your cluster is ready for this removal, please

- The kubelet and the default docker runtime now support running ephemeral containers in the Linux process namespace of a target container. Other container runtimes must implement support for this feature before it will be available for that runtime. ([#84731](https://github.com/kubernetes/kubernetes/pull/84731), [@verb](https://github.com/verb)) [SIG Node]

* Interaction with container runtimes is now through the CRI interface, enabling easier integration of runtimes with the kubelet. Docker remains the default runtime via Docker-CRI (which moves to beta).
  * **WARNING:** A [known issue](https://github.com/kubernetes/kubernetes/issues/44041)

- github.com/opencontainers/runc: [v1.0.0-rc93 → v1.0.1](https://github.com/opencontainers/runc/compare/v1.0.0-rc93...v1.0.1)
- github.com/opencontainers/runtime-spec: [e6143ca → 1c3f411](https://github.com/opencontainers/runtime-spec/compare/e6143ca...1c3f411)
- github.com/opencontainers/selinux: [v1.8.0 → v1.8.2](https://github.com/opencontainers/selinux/compare/v1.8.0...v1.8.2)

      <scope>test</scope>
    </dependency>

    <dependency>
      <groupId>maven-test-runtime</groupId>
      <artifactId>scope-runtime</artifactId>
      <version>1.0</version>
      <scope>runtime</scope>
    </dependency>

    <dependency>
      <groupId>maven-test-runtime</groupId>
      <artifactId>scope-compile</artifactId>
      <version>1.0</version>
      <scope>compile</scope>
    </dependency>

  </dependencies>

  Noteable changes:
  1. Populate new `RuntimeHandler` field in CRI's `ImageSpec` struct during image pulls from container runtimes.
  2. Pass `runtimeHandler` field in `RemoveImage()` call to container runtime in `kubelet`'s image garbage collection. ([#121456](https://github.com/kubernetes/kubernetes/pull/121456), [@kiashok](https://github.com/kiashok))