You can support us by downloading this article as PDF from the Link below. Download the guide as PDF

CRI-O is an OCI-based implementation of Kubernetes Container Runtime Interface (CRI). CRI-O is meant to provide an integration path between OCI conformant runtimes and the kubelet. In this guide, we will discuss on the installation of CRI-O Container Runtime on CentOS 8 / CentOS 7 Linux system. The scope of CRI-O is restricted to the following functionalities:

  • Support multiple image formats including the existing Docker image format
  • Support for multiple means to download images including trust & image verification
  • Container image management (managing image layers, overlay filesystems, etc)
  • Container process lifecycle management
  • Monitoring and logging required to satisfy the CRI
  • Resource isolation as required by the CRI

CRI-O use best of breed libraries for different aspects:

Install CRI-O Container Runtime on CentOS 8 / CentOS 7

CRI-O and Kubernetes follow the same release cycle and deprecation policy. For more information visit the Kubernetes versioning documentation. Update your system prior to installation:

sudo yum -y update

Below are the steps you’ll follow to install CRI-O on CentOS 8 / CentOS 7 Linux server or Workstation machine.

Step 1: Add CRI-O Repository

So if you’re running Kubernetes version 1.17, you’ll install cri-o 1.17.x. We’ll save this version to a variable. Then add repository to our system.

Add repository to CentOS 8:

VERSION=1.17
sudo dnf -y install 'dnf-command(copr)'
sudo dnf -y copr enable rhcontainerbot/container-selinux
sudo curl -L -o /etc/yum.repos.d/devel:kubic:libcontainers:stable.repo https://download.opensuse.org/repositories/devel:kubic:libcontainers:stable/CentOS_8/devel:kubic:libcontainers:stable.repo
sudo curl -L -o /etc/yum.repos.d/devel:kubic:libcontainers:stable:cri-o:${VERSION}.repo https://download.opensuse.org/repositories/devel:kubic:libcontainers:stable:cri-o:${VERSION}/CentOS_8/devel:kubic:libcontainers:stable:cri-o:${VERSION}.repo

Add repository to CentOS 7:

VERSION=1.17
sudo curl -L -o /etc/yum.repos.d/devel:kubic:libcontainers:stable.repo https://download.opensuse.org/repositories/devel:kubic:libcontainers:stable/CentOS_7/devel:kubic:libcontainers:stable.repo
sudo curl -L -o /etc/yum.repos.d/devel:kubic:libcontainers:stable:cri-o:${VERSION}.repo https://download.opensuse.org/repositories/devel:kubic:libcontainers:stable:cri-o:${VERSION}/CentOS_7/devel:kubic:libcontainers:stable:cri-o:${VERSION}.repo

Step 2: Install CRI-O Container Runtime on CentOS 8 / CentOS 7

Once the repository is added, install CRI-O Container Runtime on CentOS 8 / CentOS 7 with this command:

sudo yum install cri-o

Agree to install a number of dependencies shown:

Transaction Summary
========================================================================================================================================================
Install  19 Packages
Upgrade   8 Packages

Total download size: 91 M
Is this ok [y/N]: y

GPG key should be imported as well.

......   
Importing GPG key 0x75060AA4:
 Userid     : "devel:kubic OBS Project <devel:[email protected]>"
 Fingerprint: 2472 D6D0 D2F6 6AF8 7ABA 8DA3 4D64 3903 7506 0AA4
 From       : http://download.opensuse.org/repositories/devel:/kubic:/libcontainers:/stable:/cri-o:/1.17/CentOS_8/repodata/repomd.xml.key
Is this ok [y/N]: y

Confirm installation of CRI-O on CentOS:

$ rpm -qi cri-o
Name        : cri-o
Epoch       : 2
Version     : 1.17.2
Release     : 1.2.el8
Architecture: x86_64
Install Date: Tue 21 Apr 2020 03:13:42 PM UTC
Group       : Unspecified
Size        : 171568080
License     : ASL 2.0
Signature   : RSA/SHA256, Tue 14 Apr 2020 03:44:45 AM UTC, Key ID 4d64390375060aa4
Source RPM  : cri-o-1.17.2-1.2.el8.src.rpm
Build Date  : Tue 14 Apr 2020 03:44:06 AM UTC
Build Host  : localhost
Relocations : (not relocatable)
Vendor      : obs://build.opensuse.org/devel:kubic
URL         : https://github.com/cri-o/cri-o
Summary     : Kubernetes Container Runtime Interface for OCI-based containers

Step 3: Start CRI-O Service

The cri-o service is not enabled or started by default. Let’s start it:

sudo systemctl enable --now cri-o

In the guides to follow, we’ll cover creation of Kubernetes Cluster with CRI-O runtime engine and maybe interacting with cri-o containers with crictl command line tool.

In the meantime, check other container related articles available on our site.

How To Open a Shell Prompt on an OpenShift Node

How To Install Kubernetes Dashboard with NodePort

How To Create Admin User to Access Kubernetes Dashboard

Top Minimal Container Operating Systems for running Kubernetes

You can support us by downloading this article as PDF from the Link below. Download the guide as PDF