In recent years, container orchestration has become a key element in Cloud technologies and automated application deployment. Kubernetes has evolved as the de facto standard for container orchestration, necessitating efficient and flexible solutions for running containers. While Docker has long been a dominant player in this space, alternative solutions like CRI-O offer enhanced integration and optimization for Kubernetes environments. This article provides a detailed guide on installing and configuring CRI-O on CentOS 7 as an alternative to Docker for running containers in Kubernetes.
Prerequisites
- Clean installation of CentOS 7
- Access to root user or a user with sudo privileges
- Installed and configured Kubernetes cluster
1. System Preparation First, prepare the system for installing CRI-O. This includes updating the system and installing necessary dependencies.
sudo yum update -y
sudo yum install -y yum-utils device-mapper-persistent-data lvm2
2. Adding CRI-O Repository CRI-O is not available in the default CentOS 7 repositories, so add the official CRI-O repository.
sudo yum-config-manager --add-repo=https://cbs.centos.org/repos/paas7-crio-115-release/x86_64/os/
3. Installing CRI-O After adding the repository, install CRI-O along with required modules.
sudo yum install -y cri-o
4. Starting and Enabling CRI-O After installation, start CRI-O and enable it to start automatically on system boot.
sudo systemctl start crio
sudo systemctl enable crio
5. Configuring Kubernetes to Use CRI-O To make Kubernetes use CRI-O as its container runtime, adjust the kubelet configuration.
- Open the kubelet configuration file:
sudo vi /etc/kubernetes/kubelet - Set the runtime to CRI-O by adding the following line:
--container-runtime=remote --container-runtime-endpoint='unix:///var/run/crio/crio.sock' --runtime-request-timeout=10m - Restart the kubelet service:
sudo systemctl restart kubelet
6. Verification of Installation After completing the configuration, you can verify if Kubernetes successfully uses CRI-O as the container runtime.
kubectl get nodes -o wide
The output should display information about your nodes with CRI-O as the runtime.
CRI-O offers an efficient and optimized alternative to Docker for running containers in Kubernetes. By following the steps outlined in this article, you can easily install and configure CRI-O on CentOS 7 and leverage its full potential in your Kubernetes cluster.
