294 lines
8.4 KiB
Markdown
294 lines
8.4 KiB
Markdown
---
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reviewers:
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- vincepri
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- bart0sh
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title: CRI installation
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content_template: templates/concept
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weight: 100
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---
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{{% capture overview %}}
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{{< feature-state for_k8s_version="v1.6" state="stable" >}}
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To run containers in Pods, Kubernetes uses a container runtime. Here are
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the installation instructions for various runtimes.
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{{% /capture %}}
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{{% capture body %}}
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{{< caution >}}
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A flaw was found in the way runc handled system file descriptors when running containers.
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A malicious container could use this flaw to overwrite contents of the runc binary and
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consequently run arbitrary commands on the container host system.
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Please refer to this link for more information about this issue
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[cve-2019-5736 : runc vulnerability ] (https://access.redhat.com/security/cve/cve-2019-5736)
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{{< /caution >}}
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### Applicability
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{{< note >}}
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This document is written for users installing CRI onto Linux. For other operating
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systems, look for documentation specific to your platform.
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{{< /note >}}
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You should execute all the commands in this guide as `root`. For example, prefix commands
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with `sudo `, or become `root` and run the commands as that user.
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### Cgroup drivers
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When systemd is chosen as the init system for a Linux distribution, the init process generates
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and consumes a root control group (`cgroup`) and acts as a cgroup manager. Systemd has a tight
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integration with cgroups and will allocate cgroups per process. It's possible to configure your
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container runtime and the kubelet to use `cgroupfs`. Using `cgroupfs` alongside systemd means
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that there will then be two different cgroup managers.
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Control groups are used to constrain resources that are allocated to processes.
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A single cgroup manager will simplify the view of what resources are being allocated
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and will by default have a more consistent view of the available and in-use resources. When we have
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two managers we end up with two views of those resources. We have seen cases in the field
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where nodes that are configured to use `cgroupfs` for the kubelet and Docker, and `systemd`
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for the rest of the processes running on the node becomes unstable under resource pressure.
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Changing the settings such that your container runtime and kubelet use `systemd` as the cgroup driver
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stabilized the system. Please note the `native.cgroupdriver=systemd` option in the Docker setup below.
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{{< caution >}}
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Changing the cgroup driver of a Node that has joined a cluster is highly unrecommended.
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If the kubelet has created Pods using the semantics of one cgroup driver, changing the container
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runtime to another cgroup driver can cause errors when trying to re-create the PodSandbox
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for such existing Pods. Restarting the kubelet may not solve such errors. The recommendation
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is to drain the Node from its workloads, remove it from the cluster and re-join it.
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{{< /caution >}}
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## Docker
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On each of your machines, install Docker.
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Version 18.06.2 is recommended, but 1.11, 1.12, 1.13, 17.03 and 18.09 are known to work as well.
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Keep track of the latest verified Docker version in the Kubernetes release notes.
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Use the following commands to install Docker on your system:
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{{< tabs name="tab-cri-docker-installation" >}}
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{{< tab name="Ubuntu 16.04" codelang="bash" >}}
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# Install Docker CE
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## Set up the repository:
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### Install packages to allow apt to use a repository over HTTPS
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apt-get update && apt-get install apt-transport-https ca-certificates curl software-properties-common
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### Add Docker’s official GPG key
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curl -fsSL https://download.docker.com/linux/ubuntu/gpg | apt-key add -
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### Add Docker apt repository.
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add-apt-repository \
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"deb [arch=amd64] https://download.docker.com/linux/ubuntu \
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$(lsb_release -cs) \
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stable"
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## Install Docker CE.
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apt-get update && apt-get install docker-ce=18.06.2~ce~3-0~ubuntu
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# Setup daemon.
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cat > /etc/docker/daemon.json <<EOF
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{
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"exec-opts": ["native.cgroupdriver=systemd"],
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"log-driver": "json-file",
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"log-opts": {
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"max-size": "100m"
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},
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"storage-driver": "overlay2"
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}
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EOF
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mkdir -p /etc/systemd/system/docker.service.d
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# Restart docker.
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systemctl daemon-reload
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systemctl restart docker
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{{< /tab >}}
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{{< tab name="CentOS/RHEL 7.4+" codelang="bash" >}}
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# Install Docker CE
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## Set up the repository
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### Install required packages.
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yum install yum-utils device-mapper-persistent-data lvm2
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### Add Docker repository.
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yum-config-manager \
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--add-repo \
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https://download.docker.com/linux/centos/docker-ce.repo
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## Install Docker CE.
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yum update && yum install docker-ce-18.06.2.ce
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## Create /etc/docker directory.
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mkdir /etc/docker
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# Setup daemon.
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cat > /etc/docker/daemon.json <<EOF
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{
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"exec-opts": ["native.cgroupdriver=systemd"],
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"log-driver": "json-file",
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"log-opts": {
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"max-size": "100m"
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},
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"storage-driver": "overlay2",
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"storage-opts": [
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"overlay2.override_kernel_check=true"
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]
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}
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EOF
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mkdir -p /etc/systemd/system/docker.service.d
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# Restart Docker
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systemctl daemon-reload
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systemctl restart docker
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{{< /tab >}}
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{{< /tabs >}}
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Refer to the [official Docker installation guides](https://docs.docker.com/engine/installation/)
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for more information.
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## CRI-O
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This section contains the necessary steps to install `CRI-O` as CRI runtime.
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Use the following commands to install CRI-O on your system:
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### Prerequisites
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```shell
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modprobe overlay
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modprobe br_netfilter
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# Setup required sysctl params, these persist across reboots.
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cat > /etc/sysctl.d/99-kubernetes-cri.conf <<EOF
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net.bridge.bridge-nf-call-iptables = 1
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net.ipv4.ip_forward = 1
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net.bridge.bridge-nf-call-ip6tables = 1
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EOF
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sysctl --system
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```
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{{< tabs name="tab-cri-cri-o-installation" >}}
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{{< tab name="Ubuntu 16.04" codelang="bash" >}}
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# Install prerequisites
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apt-get update
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apt-get install software-properties-common
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add-apt-repository ppa:projectatomic/ppa
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apt-get update
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# Install CRI-O
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apt-get install cri-o-1.11
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{{< /tab >}}
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{{< tab name="CentOS/RHEL 7.4+" codelang="bash" >}}
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# Install prerequisites
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yum-config-manager --add-repo=https://cbs.centos.org/repos/paas7-crio-311-candidate/x86_64/os/
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# Install CRI-O
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yum install --nogpgcheck cri-o
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{{< /tab >}}
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{{< /tabs >}}
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### Start CRI-O
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```
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systemctl start crio
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```
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Refer to the [CRI-O installation guide](https://github.com/kubernetes-sigs/cri-o#getting-started)
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for more information.
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## Containerd
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This section contains the necessary steps to use `containerd` as CRI runtime.
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Use the following commands to install Containerd on your system:
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### Prerequisites
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```shell
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modprobe overlay
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modprobe br_netfilter
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# Setup required sysctl params, these persist across reboots.
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cat > /etc/sysctl.d/99-kubernetes-cri.conf <<EOF
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net.bridge.bridge-nf-call-iptables = 1
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net.ipv4.ip_forward = 1
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net.bridge.bridge-nf-call-ip6tables = 1
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EOF
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sysctl --system
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```
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### Install containerd
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{{< tabs name="tab-cri-containerd-installation" >}}
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{{< tab name="Ubuntu 16.04" codelang="bash" >}}
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# Install containerd
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## Set up the repository
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### Install packages to allow apt to use a repository over HTTPS
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apt-get update && apt-get install -y apt-transport-https ca-certificates curl software-properties-common
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### Add Docker’s official GPG key
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curl -fsSL https://download.docker.com/linux/ubuntu/gpg | apt-key add -
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### Add Docker apt repository.
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add-apt-repository \
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"deb [arch=amd64] https://download.docker.com/linux/ubuntu \
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$(lsb_release -cs) \
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stable"
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## Install containerd
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apt-get update && apt-get install -y containerd.io
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# Configure containerd
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mkdir -p /etc/containerd
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containerd config default > /etc/containerd/config.toml
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# Restart containerd
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systemctl restart containerd
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{{< /tab >}}
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{{< tab name="CentOS/RHEL 7.4+" codelang="bash" >}}
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# Install containerd
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## Set up the repository
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### Install required packages
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yum install yum-utils device-mapper-persistent-data lvm2
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### Add docker repository
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yum-config-manager \
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--add-repo \
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https://download.docker.com/linux/centos/docker-ce.repo
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## Install containerd
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yum update && yum install containerd.io
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# Configure containerd
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mkdir -p /etc/containerd
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containerd config default > /etc/containerd/config.toml
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# Restart containerd
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systemctl restart containerd
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{{< /tab >}}
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{{< /tabs >}}
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### systemd
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To use the `systemd` cgroup driver, set `plugins.cri.systemd_cgroup = true` in `/etc/containerd/config.toml`.
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When using kubeadm, manually configure the
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[cgroup driver for kubelet](/docs/setup/independent/install-kubeadm/#configure-cgroup-driver-used-by-kubelet-on-master-node)
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as well.
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## Other CRI runtimes: frakti
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Refer to the [Frakti QuickStart guide](https://github.com/kubernetes/frakti#quickstart) for more information.
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{{% /capture %}}
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