website/content/en/docs/tasks/administer-cluster/migrating-from-dockershim/change-runtime-containerd.md

title, weight, content_type

title	weight	content_type
Changing the Container Runtime on a Node from Docker Engine to containerd	8	task

This task outlines the steps needed to update your container runtime to containerd from Docker. It is applicable for cluster operators running Kubernetes 1.23 or earlier. Also this covers an example scenario for migrating from dockershim to containerd and alternative container runtimes can be picked from this page.

{{% heading "prerequisites" %}}

{{% thirdparty-content %}}

Install containerd. For more information see, containerd's installation documentation and for specific prerequisite follow this.

Drain the node

# replace <node-to-drain> with the name of your node you are draining
kubectl drain <node-to-drain> --ignore-daemonsets

Stop the Docker daemon

systemctl stop kubelet
systemctl disable docker.service --now

Install Containerd

This page contains detailed steps to install containerd.

{{< tabs name="tab-cri-containerd-installation" >}} {{% tab name="Linux" %}}

1. Install the containerd.io package from the official Docker repositories. Instructions for setting up the Docker repository for your respective Linux distribution and installing the containerd.io package can be found at Install Docker Engine.

2. Configure containerd:

   sudo mkdir -p /etc/containerd
   containerd config default | sudo tee /etc/containerd/config.toml
   

3. Restart containerd:

   sudo systemctl restart containerd
   

{{% /tab %}} {{% tab name="Windows (PowerShell)" %}}

Start a Powershell session, set $Version to the desired version (ex: $Version="1.4.3"), and then run the following commands:

1. Download containerd:

   curl.exe -L https://github.com/containerd/containerd/releases/download/v$Version/containerd-$Version-windows-amd64.tar.gz -o containerd-windows-amd64.tar.gz
   tar.exe xvf .\containerd-windows-amd64.tar.gz
   

2. Extract and configure:

   Copy-Item -Path ".\bin\" -Destination "$Env:ProgramFiles\containerd" -Recurse -Force
   cd $Env:ProgramFiles\containerd\
   .\containerd.exe config default | Out-File config.toml -Encoding ascii
   
   # Review the configuration. Depending on setup you may want to adjust:
   # - the sandbox_image (Kubernetes pause image)
   # - cni bin_dir and conf_dir locations
   Get-Content config.toml
   
   # (Optional - but highly recommended) Exclude containerd from Windows Defender Scans
   Add-MpPreference -ExclusionProcess "$Env:ProgramFiles\containerd\containerd.exe"
   

3. Start containerd:

   .\containerd.exe --register-service
   Start-Service containerd
   

{{% /tab %}} {{< /tabs >}}

Configure the kubelet to use containerd as its container runtime

Edit the file /var/lib/kubelet/kubeadm-flags.env and add the containerd runtime to the flags. --container-runtime=remote and --container-runtime-endpoint=unix:///run/containerd/containerd.sock"

For users using kubeadm should consider the following:

The kubeadm tool stores the CRI socket for each host as an annotation in the Node object for that host.

To change it you must do the following:

Execute kubectl edit no <NODE-NAME> on a machine that has the kubeadm /etc/kubernetes/admin.conf file.

This will start a text editor where you can edit the Node object.

To choose a text editor you can set the KUBE_EDITOR environment variable.

• Change the value of kubeadm.alpha.kubernetes.io/cri-socket from /var/run/dockershim.sock to the CRI socket path of your choice (for example unix:///run/containerd/containerd.sock).

  Note that new CRI socket paths must be prefixed with unix:// ideally.

• Save the changes in the text editor, which will update the Node object.

Restart the kubelet

systemctl start kubelet

Verify that the node is healthy

Run kubectl get nodes -o wide and containerd appears as the runtime for the node we just changed.

Remove Docker Engine

{{% thirdparty-content %}}

Finally if everything goes well remove docker

{{< tabs name="tab-remove-docker-enigine" >}} {{% tab name="CentOS" %}}

sudo yum remove docker-ce docker-ce-cli

{{% /tab %}} {{% tab name="Debian" %}}

sudo apt-get purge docker-ce docker-ce-cli

{{% /tab %}} {{% tab name="Fedora" %}}

sudo dnf remove docker-ce docker-ce-cli

{{% /tab %}} {{% tab name="Ubuntu" %}}

sudo apt-get purge docker-ce docker-ce-cli

{{% /tab %}} {{< /tabs >}}