Kubernetes Cluster Setup

This guide provides a step-by-step process for setting up a Kubernetes cluster with:

• A Control Plane node.
• One or more Worker Nodes.

Two scripts are included:

1. control-plane.sh: For setting up the control plane.
2. worker-node.sh: For setting up the worker nodes.

Both setups include detailed instructions and port configurations for various network add-ons like Calico, Weave, and Flannel.

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Prerequisites

1. You have at least two machines (VMs or physical) with Ubuntu installed (22.04 or later is recommended).
2. You have root or sudo access to these machines.
3. Networking is properly configured between the nodes.
4. Swap is disabled on all nodes.

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Installation Overview

Script 1: Setting Up the Control Plane

1. Download the control-plane.sh script to your control plane node:

   wget https://raw.githubusercontent.com/rspatel031/k8s-cluster-setup/refs/heads/main/control-plane.sh

2. Make the script executable:

   chmod +x control-plane.sh

3. Run the script:

   sudo ./control-plane.sh

Output:

At the end of the script, you will receive a join command for worker nodes. This is stored at:

/tmp/kubeadm-init-output.txt

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Script 2: Setting Up Worker Nodes

Important: Ensure you set the hostname before executing the worker-node.sh script.

The worker-node.sh script prepares worker nodes and joins them to the cluster.

Steps:

1. Download the worker-node.sh script to your worker node(s).

   wget https://raw.githubusercontent.com/rspatel031/k8s-cluster-setup/refs/heads/main/worker-node.sh

2. Make the script executable:

   chmod +x worker-node.sh

3. Run the script:

   sudo ./worker-node.sh

4. Once the script finishes, use the join command from the control plane node to connect the worker node to the cluster. For example:

   sudo kubeadm join <control-plane-ip>:6443 --token <token> --discovery-token-ca-cert-hash sha256:<hash>

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Script Breakdown

Control Plane Script (control-plane.sh)

The control plane script:

1. Updates and upgrades the system.
2. Sets the hostname to control-plane.
3. Disables swap for Kubernetes compatibility.
4. Configures required kernel modules and sysctl settings.
5. Installs and configures containerd.
6. Configures Kubernetes repositories.
7. Installs Kubernetes components (kubelet, kubeadm, and kubectl).
8. Initializes the Kubernetes control plane.
9. Sets crictl endpoints.
10. Deploys a default network add-on.
11. Displays the kubeadm init command output.
12. Adds kubectl aliases and autocompletion for ease of use.

Worker Node Script (worker-node.sh)

The worker node script:

1. Updates and upgrades the system.
2. Disables swap.
3. Configures required kernel modules and sysctl settings.
4. Installs and configures containerd.
5. Configures Kubernetes repositories.
6. Installs Kubernetes components (kubelet and kubeadm).

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Network Add-Ons

Kubernetes requires a network add-on to manage communication between pods. Below are the supported network add-ons with their corresponding configuration files:

• Calico:

  wget https://raw.githubusercontent.com/rspatel031/k8s-network-addon/refs/heads/main/calico/calico.yaml

• Flannel:

  wget https://raw.githubusercontent.com/rspatel031/k8s-network-addon/refs/heads/main/flannel/flannel.yaml

• Weave:

  wget https://raw.githubusercontent.com/rspatel031/k8s-network-addon/refs/heads/main/weave/weave.yaml

CIDR Configuration: All network add-ons mentioned above are preconfigured to use the 10.244.0.0/16 CIDR range.

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Port Requirements

Below are the port details required for the cluster to function properly:

Kubernetes Components

Component	Protocol	Ports	Description
Kube-API Server	TCP	6443	Kubernetes API server port.
etcd	TCP	2379-2380	Communication between etcd members.
Kubelet	TCP	10250	Worker node to API server communication.
Kube Scheduler	TCP	10251	Scheduler communication.
Kube Controller	TCP	10252	Controller-manager communication.

Network Add-Ons

Add-On	Protocol	Ports	Description
Calico	TCP/UDP	179	BGP communication between nodes.
Flannel	UDP	8285	Overlay network communication.
Flannel	UDP	8472	VXLAN communication.
Weave	TCP/UDP	6783-6784	Control plane and data plane traffic.

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Additional Notes

• Ensure ports are open and accessible between nodes in the cluster.
• Ensure you use the correct kubeadm join command on worker nodes.
• The scripts are written for Ubuntu and may require modifications for other distributions.
• The control-plane setup also deploys a Calico network add-on. You can customize the network plugin if needed.
• Restart nodes if necessary after installation.
• Use the provided configuration files to deploy any network add-on suitable for your environment.

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References

• Calico Configuration
• Flannel Configuration
• Weave Configuration