Learn Kubernetes Basics

Setup

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CRI installation

Since v1.6.0, Kubernetes has enabled the use of CRI, Container Runtime Interface, by default. This page contains installation instruction for various runtimes.

Please proceed with executing the following commands based on your OS as root. You may become the root user by executing sudo -i after SSH-ing to each host.

Docker

On each of your machines, install Docker. Version 18.06 is recommended, but 1.11, 1.12, 1.13 and 17.03 are known to work as well. Keep track of the latest verified Docker version in the Kubernetes release notes.

Use the following commands to install Docker on your system:


# Install Docker from Ubuntu's repositories:
apt-get update
apt-get install -y docker.io

# or install Docker CE 18.06 from Docker's repositories for Ubuntu or Debian:

## Install prerequisites.
apt-get update && apt-get install apt-transport-https ca-certificates curl software-properties-common

## Download GPG key.
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | apt-key add -

## Add docker apt repository.
add-apt-repository \
   "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
   $(lsb_release -cs) \
   stable"

## Install docker.
apt-get update && apt-get install docker-ce=18.06.0~ce~3-0~ubuntu

# Setup daemon.
cat > /etc/docker/daemon.json <<EOF
{
  "exec-opts": ["native.cgroupdriver=systemd"],
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "100m"
  },
  "storage-driver": "overlay2"
}
EOF

mkdir -p /etc/systemd/system/docker.service.d

# Restart docker.
systemctl daemon-reload
systemctl restart docker




# Install Docker from CentOS/RHEL repository:
yum install -y docker

# or install Docker CE 18.06 from Docker's CentOS repositories:

## Install prerequisites.
yum install yum-utils device-mapper-persistent-data lvm2

## Add docker repository.
yum-config-manager \
    --add-repo \
    https://download.docker.com/linux/centos/docker-ce.repo

## Install docker.
yum update && yum install docker-ce-18.06.1.ce

## Create /etc/docker directory.
mkdir /etc/docker

# Setup daemon.
cat > /etc/docker/daemon.json <<EOF
{
  "exec-opts": ["native.cgroupdriver=systemd"],
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "100m"
  },
  "storage-driver": "overlay2",
  "storage-opts": [
    "overlay2.override_kernel_check=true"
  ]
}
EOF

mkdir -p /etc/systemd/system/docker.service.d

# Restart docker.
systemctl daemon-reload
systemctl restart docker

Refer to the official Docker installation guides for more information.

CRI-O

This section contains the necessary steps to install CRI-O as CRI runtime.

Use the following commands to install CRI-O on your system:

Prerequisites

modprobe overlay
modprobe br_netfilter

# Setup required sysctl params, these persist across reboots.
cat > /etc/sysctl.d/99-kubernetes-cri.conf <<EOF
net.bridge.bridge-nf-call-iptables  = 1
net.ipv4.ip_forward                 = 1
net.bridge.bridge-nf-call-ip6tables = 1
EOF

sysctl --system


# Install prerequisites
apt-get update
apt-get install software-properties-common

add-apt-repository ppa:projectatomic/ppa
apt-get update

# Install CRI-O
apt-get install cri-o-1.11





# Install prerequisites
yum-config-manager --add-repo=https://cbs.centos.org/repos/paas7-crio-311-candidate/x86_64/os/

# Install CRI-O
yum install --nogpgcheck cri-o

Start CRI-O

systemctl start crio

Refer to the CRI-O installation guide for more information.

Containerd

This section contains the necessary steps to use containerd as CRI runtime.

Use the following commands to install Containerd on your system:

Prerequisites

modprobe overlay
modprobe br_netfilter

# Setup required sysctl params, these persist across reboots.
cat > /etc/sysctl.d/99-kubernetes-cri.conf <<EOF
net.bridge.bridge-nf-call-iptables  = 1
net.ipv4.ip_forward                 = 1
net.bridge.bridge-nf-call-ip6tables = 1
EOF

sysctl --system

apt-get install -y libseccomp2



yum install -y libseccomp

Install containerd

Containerd releases are published regularly, the values below are hardcoded to the latest version available at the time of writing. Please check for newer versions and hashes here.

# Export required environment variables.
export CONTAINERD_VERSION="1.1.2"
export CONTAINERD_SHA256="d4ed54891e90a5d1a45e3e96464e2e8a4770cd380c21285ef5c9895c40549218"

# Download containerd tar.
wget https://storage.googleapis.com/cri-containerd-release/cri-containerd-${CONTAINERD_VERSION}.linux-amd64.tar.gz

# Check hash.
echo "${CONTAINERD_SHA256} cri-containerd-${CONTAINERD_VERSION}.linux-amd64.tar.gz" | sha256sum --check -

# Unpack.
tar --no-overwrite-dir -C / -xzf cri-containerd-${CONTAINERD_VERSION}.linux-amd64.tar.gz

# Start containerd.
systemctl start containerd

Other CRI runtimes: rktlet and frakti

Refer to the Frakti QuickStart guide and Rktlet Getting Started guide for more information.

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