Kubernetes Installation Script

This Bash script automates the setup of a Kubernetes node, either as a control plane or a worker node, on Debian-based Linux distributions that use the apt package manager. It allows you to customise the necessary settings to bootstrap or join your node to a kubernetes cluster.

Features

• Control Plane or Worker Node Setup: Option to configure the node as a control plane or a worker node.
• Option to Initalise a High Availability Cluster: You can point your control plane endpoint to a virtual ip for highly avalible clusters.
• Container Runtime Configuration: Supports cri-o, containerd, or other container runtimes(you will have to manually install the necessary files for other container runtimes).
• CNI Setup: Automatic setup for Calico or manual setup for other CNIs.
• Firewall Configuration: Installs and configures UFW with necessary Kubernetes ports.
• Kubernetes Installation: Installs specific versions of Kubernetes components (kubeadm, kubelet, kubectl).
• Automated Cluster Initialization: Initializes the Kubernetes control plane or joins a worker node to an existing cluster.

Prerequisites

• Ubuntu or Debian-based Linux distribution.
• root or sudo access.
• network connectivity to download packages and container images.

if you are joining the node to an existing cluster then you will also need:

• Control plane endpoint (including the port)
• Cluster token

you can generate a cluster token by running kubeadm token create

Usage

Disclaimer: Use this script at your own risk. Ensure you have backups and understand the script and configurations being applied.

1. Install curl if your distro doesn't have it:

   apt install curl

2. Download the script:

   curl -O https://raw.githubusercontent.com/Quarterpie3141/Kubernetes-install-script/main/kubernetes-install.sh

3. Make the script executable:

   chmod +x ./kubernetes-install.sh

4. Run the script

   ./kubernetes-install.sh

5. Follow the CLI prompts to configure your cluster(see below)

Configuration Option	Description	Default Value
Node Type	Choose whether this is a control plane or a worker node.	control-plane
Control Plane Endpoint	If setting up a highly available control plane, you can define a control plane endpoint.	N/A
Control Plane Address	For worker nodes, specify the control plane address and port.	N/A
Cluster Token	The existing cluster token for joining worker nodes.	N/A
Kubernetes Version	Specify the Kubernetes version.*	v1.31
Container Runtime	Select the container runtime (cri-o, containerd, or other).	cri-o
Container Runtime Version	Select the container runtime version.**	v1.30 (for cri-o)
CNI	Choose the Container Network Interface.	calico
Pod CIDR	Specify your pod IP address range.***	192.168.0.0/16
Control Plane Taint	Specify if you want to taint your control plane.	no
Firewall Ports	Specify the NodePort range and whether to allow SSH access through UFW.	30000:32767/tcp for NodePorts, no for SSH

_{* You can find the most recent version of kuberentes here.
** You can find the most recent version of CRI-O here.
*** The default value is the recommended value for Calico, please read the installation instructions of your chosen CNI for more info on the appropriate CIDR.}

Troubleshooting

If the script fails at any point:

• Ensure you have an active internet connection.
• Check if the necessary ports are open on your firewall(ufw status).
• Verify that the correct Kubernetes and container runtime versions are specified.
• Use kubectl get pods -n kube-system and kubectl describe pod -n kube-system <pod-name> to troubleshoot any failed components.
• If all else fails then follow the quick start guide manually

Contributing

Contributions are welcome! Please fork this repository, create a new branch, and submit a pull request.

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Disclaimer: Use this script at your own risk. Ensure you have backups and understand the script and configurations being applied.

Script Workflow and Detailed Steps

1. Initial Prompts and Configuration

• Starting Install Script: The script begins by confirming whether the node is a control plane or a worker node.
• Control Plane Configuration:
  • If it's a control plane, you can optionally specify a control plane endpoint for a highly available setup.
  • If it's a worker node, you are prompted to provide the control plane's address and port along with the cluster token.
• Kubernetes Version: The script prompts for the Kubernetes version to install.
• Container Runtime: You are asked to select a container runtime (cri-o, containerd, or other) and provide the version if applicable.
• CNI Configuration:
  • If the node is a control plane, you are prompted to choose a Container Network Interface (CNI) and specify the pod network CIDR.
• Pod CIDR Configuration You can specify the pod network CIDR.
• Taint Control Plane: Optionally, you can taint the control plane to prevent workloads from running on it.
• Firewall Configuration: The script asks for the desired NodePort range and whether to allow SSH (port 22) through the firewall.

2. Validation of Configurations

• Final Confirmation: Before proceeding, the script displays all the gathered information and asks for final confirmation to ensure the values are correct.

3. Pre-installation Tasks

• Updating Packages: The script updates the system’s package list and upgrades installed packages.
• Disabling Swap: If any swap space is active, the script disables it, as Kubernetes requires swap to be turned off.
• Loading Kernel Modules: Ensures the necessary kernel modules, like br_netfilter, are loaded for Kubernetes networking.
• Enabling IPv4 Packet Forwarding: Configures the system to enable IPv4 packet forwarding, which is required for Kubernetes networking.

4. Firewall Configuration

• Installing UFW: The script installs UFW (Uncomplicated Firewall) if it’s not already installed.
• Configuring UFW:
  • It opens the required ports for Kubernetes components such as the API server, etcd, kubelet, kube-proxy, and others.
  • If Calico is selected as the CNI, it also opens ports for BIRD and Typha.
  • Optionally, it allows SSH access through port 22.
• Enabling UFW: The script enables the UFW firewall with the configured rules.

5. Container Runtime Installation

• Installing CRI-O: If CRI-O is selected, the script installs and configures CRI-O as the container runtime.
• Installing Containerd: If Containerd is selected, the script installs and configures Containerd.
• Manual Runtime Installation: If another runtime is selected, the script advises manual installation and configuration.

6. Kubernetes Installation

• Installing Kubernetes: The script installs the Kubernetes components (kubeadm, kubelet, and kubectl) using the specified version.
• Pulling Kubernetes Images: It pre-pulls necessary Kubernetes images using kubeadm config images pull to prepare for cluster initialization.

7. Control Plane Initialization (For Control Plane Nodes)

• Initializing the Control Plane:
  • The script initializes the control plane using kubeadm init, configuring the control plane endpoint and pod network CIDR.
  • It sets up the kubeconfig file for the user to interact with the cluster using kubectl.
  • If the control plane is not tainted, it removes the taint to allow workloads to be scheduled on it.
• Installing Calico: If Calico is selected, it applies the Calico manifests to set up the CNI.

8. Worker Node Join (For Worker Nodes)

• Joining the Cluster: The script generates a certificate hash and uses the provided token to join the worker node to the control plane.

9. Finalization

• Node Status: The script checks the status of the nodes using kubectl get nodes to ensure everything is configured correctly.