k8s-installation-requirements.md

⚙️ Kubernetes Installation Requirements

Essential prerequisites for installing Kubernetes using kubeadm or other self-managed methods.

---

🖥️ Operating System

Kubernetes control plane components are supported only on Linux.

✅ Supported Linux Families:

• Red Hat-based
  (e.g., RHEL, CentOS, AlmaLinux, Rocky Linux, Oracle Linux)
• Debian-based
  (e.g., Ubuntu, Debian)
• SUSE-based
  (e.g., openSUSE, SLES)

🪟 Windows nodes can be added as worker nodes only in hybrid clusters, but are rare and used for specific workloads.

---

🧠 Minimum System Specifications

Component	Requirement
CPU	2 cores
RAM	2 GB
Disk	20 GB
Network	Stable connectivity between all nodes

---

🚫 Swap Must Be Disabled

Kubernetes requires swap to be turned off.

---

🧱 Container Runtime Interface (CRI)

Kubernetes uses the Container Runtime Interface (CRI) to interact with container runtimes.
You must install and configure a CRI-compatible runtime before initializing the cluster.

✅ Supported CRI Runtimes:

Runtime	Notes
containerd	✅ Default and recommended since Kubernetes 1.24+
CRI-O	Lightweight, OpenShift-compatible alternative
Docker (via cri-dockerd)	Deprecated since v1.24; supported only through cri-dockerd shim

🔥 As of Kubernetes v1.24, Docker is no longer supported natively — use containerd or CRI-O for production clusters.

---

🧬 Node Identity & System Uniqueness

Each Kubernetes node must have a unique identity to prevent conflicts during registration and scheduling.

✅ Required Unique Identifiers per Node:

Component	Purpose
Hostname	Used internally by kubelet and DNS
MAC Address	Important for network identification (CNI, DHCP)
Machine ID (/etc/machine-id)	Used by systemd and kubelet
Product UUID (/sys/class/dmi/id/product_uuid)	Used by kubelet to identify the node

⚠️ In case of VM cloning, ensure the above identifiers are unique on each node before joining the cluster.

---