Find Out What Container Runtime is Used on a Node

This page outlines steps to find out what container runtime the nodes in your cluster use.

Depending on the way you run your cluster, the container runtime for the nodes may have been pre-configured or you need to configure it. If you’re using a managed Kubernetes service, there might be vendor-specific ways to check what container runtime is configured for the nodes. The method described on this page should work whenever the execution of kubectl is allowed.

Before you begin

Install and configure kubectl. See Install Tools section for details.

Find out the container runtime used on a Node

Use kubectl to fetch and show node information:

  1. kubectl get nodes -o wide

The output is similar to the following. The column CONTAINER-RUNTIME outputs the runtime and its version.

For Docker Engine, the output is similar to this:

  1. NAME         STATUS   VERSION    CONTAINER-RUNTIME
  2. node-1       Ready    v1.16.15   docker://19.3.1
  3. node-2       Ready    v1.16.15   docker://19.3.1
  4. node-3       Ready    v1.16.15   docker://19.3.1

If your runtime shows as Docker Engine, you still might not be affected by the removal of dockershim in Kubernetes v1.24. Check the runtime endpoint to see if you use dockershim. If you don’t use dockershim, you aren’t affected.

For containerd, the output is similar to this:

  1. NAME         STATUS   VERSION   CONTAINER-RUNTIME
  2. node-1       Ready    v1.19.6   containerd://1.4.1
  3. node-2       Ready    v1.19.6   containerd://1.4.1
  4. node-3       Ready    v1.19.6   containerd://1.4.1

Find out more information about container runtimes on Container Runtimes page.

Find out what container runtime endpoint you use

The container runtime talks to the kubelet over a Unix socket using the CRI protocol, which is based on the gRPC framework. The kubelet acts as a client, and the runtime acts as the server. In some cases, you might find it useful to know which socket your nodes use. For example, with the removal of dockershim in Kubernetes v1.24 and later, you might want to know whether you use Docker Engine with dockershim.

Note:

If you currently use Docker Engine in your nodes with cri-dockerd, you aren’t affected by the dockershim removal.

You can check which socket you use by checking the kubelet configuration on your nodes.

  1. Read the starting commands for the kubelet process:

    1. tr \\0 ' ' < /proc/"$(pgrep kubelet)"/cmdline

    If you don’t have tr or pgrep, check the command line for the kubelet process manually.

  2. In the output, look for the --container-runtime flag and the --container-runtime-endpoint flag.

    • If your nodes use Kubernetes v1.23 and earlier and these flags aren’t present or if the --container-runtime flag is not remote, you use the dockershim socket with Docker Engine. The --container-runtime command line argument is not available in Kubernetes v1.27 and later.
    • If the --container-runtime-endpoint flag is present, check the socket name to find out which runtime you use. For example, unix:///run/containerd/containerd.sock is the containerd endpoint.

If you want to change the Container Runtime on a Node from Docker Engine to containerd, you can find out more information on migrating from Docker Engine to containerd, or, if you want to continue using Docker Engine in Kubernetes v1.24 and later, migrate to a CRI-compatible adapter like cri-dockerd.