Installing a Kubernetes Cluster on RHEL8

Kubernetes has become the de facto standard for container orchestration, and Red Hat Enterprise Linux 8 (RHEL8) is one of the most popular platforms for running Kubernetes. In this post, we will explore how to install a Kubernetes cluster on RHEL8.

Before we begin, it’s important to note that Kubernetes requires a few specific settings to be disabled in order to function properly. These include disabling swap and enabling the SELinux (Security-Enhanced Linux) feature. We will cover these steps first before moving on to the installation process.

Disabling Swap

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The first step is to disable swap, which can cause issues with Kubernetes. To do this, run the following command:

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sudo swapoff -a

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This command will disable all swap spaces on the system.

Disabling SELinux

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SELinux (Security-Enhanced Linux) is a feature that provides an additional layer of security by enforcing strict access controls. While it can be useful in some environments, it is not compatible with Kubernetes. To disable SELinux, run the following command:

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sudo sed -i ‘s/SELINUX=enforcing/SELINUX=permissive/’ /etc/selinux/config

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This will change the SELinux configuration to permissive mode, which is less restrictive and more compatible with Kubernetes.

Installing Kubernetes

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Now that the necessary settings have been disabled, we can begin the installation process. We will use the following commands to install Kubernetes:

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sudo yum install -y kubeadm kubectl

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The first command installs the kubeadm package, which is the main component of Kubernetes. The second command installs the kubectl command-line tool, which is used to interact with the Kubernetes cluster.

After installing the packages, we need to configure the Kubernetes cluster. To do this, run the following command:

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sudo kubeadm config –pod-network-cidr=10.244.0.0/16

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This command sets the pod network CIDR (Classless Inter-Domain Routing) block to 10.244.0.0/16, which is a commonly used range for Kubernetes pod networks.

Next, we need to create the Kubernetes cluster. To do this, run the following command:

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sudo kubeadm init

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This command will create the Kubernetes cluster and start the control plane components (API server, controller manager, and scheduler).

Finally, we can join the nodes to the Kubernetes cluster. To do this, run the following command on each node:

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sudo kubeadm join –discovery-token

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Replace with the IP address of the node you are working on, and replace with a unique token that is generated by the kubeadm init command.

That’s it! You have now successfully installed a Kubernetes cluster on RHEL8. You can verify the installation by running the following command:

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sudo kubectl get nodes

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This command will list all the nodes in the Kubernetes cluster, including the node you are working on.

Conclusion

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In this post, we have covered the steps for installing a Kubernetes cluster on RHEL8. We have disabled swap and SELinux, installed the kubeadm and kubectl packages, configured the pod network CIDR block, created the Kubernetes cluster, and joined the nodes to the cluster. With these steps, you should now have a functional Kubernetes cluster running on RHEL8.