Docs to change Container runtime

content/en/docs/tasks/administer-cluster/migrating-from-dockershim/Change-runtime.md

@@ -0,0 +1,115 @@
+---
+title: "Migrating Container runtime from dockershim to containerd"
+weight: 10
+content_type: task 
+---
+
+- Drain Node
+```
+# replace <node-to-drain> with the name of your node you are draining
+kubectl drain <node-to-drain> --ignore-daemonsets
+```
+- Stop docker
+```
+systemctl stop kubelet
+systemctl stop docker
+```
+- Install & start containerd 
+
+
+### For linux systems
+Use the following commands to install Containerd on your system:
+
+Install and configure prerequisites:
+
+```shell
+cat <<EOF | sudo tee /etc/modules-load.d/containerd.conf
+overlay
+br_netfilter
+EOF
+
+sudo modprobe overlay
+sudo modprobe br_netfilter
+
+# Setup required sysctl params, these persist across reboots.
+cat <<EOF | sudo tee /etc/sysctl.d/99-kubernetes-cri.conf
+net.bridge.bridge-nf-call-iptables  = 1
+net.ipv4.ip_forward                 = 1
+net.bridge.bridge-nf-call-ip6tables = 1
+EOF
+
+# Apply sysctl params without reboot
+sudo sysctl --system
+```
+
+Install containerd:
+
+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](https://docs.docker.com/engine/install/#server).
+
+2. Configure containerd:
+
+   ```shell
+   sudo mkdir -p /etc/containerd
+   containerd config default | sudo tee /etc/containerd/config.toml
+   ```
+
+3. Restart containerd:
+
+   ```shell
+   sudo systemctl restart containerd
+   ```
+### For 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:
+
+   ```powershell
+   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:
+
+   ```powershell
+   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:
+
+   ```powershell
+   .\containerd.exe --register-service
+   Start-Service containerd
+   ```
+- configure kubelet to use containerd
+Edit the file `/var/lib/kubelet/kubeadm-flags.env` and add the containerd runtime to the flags. `--container-runtime=remote` and `--container-runtimeendpoint=unix:///run/containerd/containerd.sock"`
+
+- restart kubelet
+`systemctl start kubelet`
+
+- verify pods are running 
+Run `kubectl get nodes -o wide` and containerd appears as the runtime for the node we just changed.
+
+- finally if everything goes well remove docker
+```
+apt purge docker-ce docker-ce-cli
+OR
+yum remove docker-ce docker-ce-cli
+```
+
+
+