How to Install CRI-O on Ubuntu For Kubernetes?

A step-by-step guide to installing cri-o container runtime on Ubuntu for kubeadm kubernetes setup.

Here is what you should know about crio

1. cri-o is an open-source container runtime created by the open-source community to replace the Docker engine on Kubernetes.
2. cri-o is a stable container engine that runs OCI-compliant runtimes.
3. cri-o is very stable because it is developed along with Kubernetes.

Install CRI-O on Ubuntu

You can install cri-o runtime easily on Ubuntu using the following four steps.

Step 1: Add the cri-o repository from OpenSUSE.

First, we need to add the cri-o repository from the openSUSE repo. The version we are using is 1.28

OS="xUbuntu_22.04"
VERSION="1.28"

echo "deb https://download.opensuse.org/repositories/devel:/kubic:/libcontainers:/stable/$OS/ /" | sudo tee /etc/apt/sources.list.d/devel:kubic:libcontainers:stable.list
echo "deb http://download.opensuse.org/repositories/devel:/kubic:/libcontainers:/stable:/cri-o:/$VERSION/$OS/ /" | sudo tee /etc/apt/sources.list.d/devel:kubic:libcontainers:stable:cri-o:$VERSION.list

Step 2: Add the cri-o gpg keys

Add the cri-o gpg release key to verify the downloaded package.

curl -L https://download.opensuse.org/repositories/devel:kubic:libcontainers:stable:cri-o:$VERSION/$OS/Release.key | sudo apt-key --keyring /etc/apt/trusted.gpg.d/libcontainers.gpg add -
curl -L https://download.opensuse.org/repositories/devel:/kubic:/libcontainers:/stable/$OS/Release.key | sudo apt-key --keyring /etc/apt/trusted.gpg.d/libcontainers.gpg add -

Step 3: Update and install cri-o

Run an update and install. crio and crio-runc packages.

sudo apt-get update
sudo apt-get install cri-o cri-o-runc cri-tools -y

Step 4: Reload and enable cri-o

Reload the systemd confirmations and enable crio utility to start on re-boots.

sudo systemctl daemon-reload
sudo systemctl enable crio --now

Step 5: Verify cri-o installation using crictl.

crictl utility is part of the cri-tools package. It is the CLI to interact with cri-o

sudo crictl info

You should see a JSON output as shown below.

{
  "status": {
    "conditions": [
      {
        "type": "RuntimeReady",
        "status": true,
        "reason": "",
        "message": ""
      },
      {
        "type": "NetworkReady",
        "status": false,
        "reason": "NetworkPluginNotReady",
        "message": "Network plugin returns error: No CNI configuration file in /etc/cni/net.d/. Has your network provider started?"
      }
    ]
  }
}

Conclusion

When it comes to kubeadm Kubernetes setup, you need a container runtime like cri-o. Also, it is an important concept in Kubernetes certification exams. In the CKS certification exam, you will have to use the crictl command line utility for troubleshooting.

If you are preparing for Kubernetes certification, check out the CKA exam guide and use the CKA coupon to get discounts on certification registration.

If you are learning Kubernetes, check out the best Kubernetes tutorials.