311 lines
9.0 KiB
Bash
311 lines
9.0 KiB
Bash
#!/usr/bin/env bash
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set -Eeuo pipefail
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###############################################################################
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# Arch Linux Kubernetes bootstrap script
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#
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# What this script does:
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# 1. Updates the system
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# 2. Replaces legacy iptables with iptables-nft in one transaction
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# 3. Installs Kubernetes packages and containerd
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# 4. Configures containerd to use systemd cgroups
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# 5. Enables required kernel modules and sysctl settings
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# 6. Disables swap now and on reboot
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# 7. Enables containerd and kubelet
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# 8. Initializes a single control-plane node with kubeadm
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# 9. Configures kubectl for the invoking user
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# 10. Installs Flannel CNI
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# 11. Optionally allows scheduling pods on the control-plane node
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#
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# Notes:
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# - This script is intended for a fresh/single-node lab setup.
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# - Re-running is mostly safe; it skips kubeadm init if already initialized.
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# - Run it as:
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# sudo ./arch_k8s_bootstrap.sh
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###############################################################################
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#######################################
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# User-tunable variables
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#######################################
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# Pod CIDR required by Flannel docs
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POD_CIDR="${POD_CIDR:-10.244.0.0/16}"
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# Flannel manifest URL from current flannel docs/releases
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FLANNEL_MANIFEST_URL="${FLANNEL_MANIFEST_URL:-https://github.com/flannel-io/flannel/releases/latest/download/kube-flannel.yml}"
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# Set to "true" if this is a single-node lab and you want workloads allowed
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# on the control-plane node after setup.
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ALLOW_PODS_ON_CONTROL_PLANE="${ALLOW_PODS_ON_CONTROL_PLANE:-true}"
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# The user who should receive ~/.kube/config.
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# If script is run with sudo, prefer the original user.
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TARGET_USER="${SUDO_USER:-root}"
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# Figure out that user's home directory safely.
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if [[ "${TARGET_USER}" == "root" ]]; then
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TARGET_HOME="/root"
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else
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TARGET_HOME="$(getent passwd "${TARGET_USER}" | cut -d: -f6)"
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fi
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#######################################
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# Helper functions
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#######################################
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log() {
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printf '\n[%s] %s\n' "$(date '+%F %T')" "$*"
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}
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die() {
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printf '\n[ERROR] %s\n' "$*" >&2
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exit 1
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}
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require_root() {
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[[ "${EUID}" -eq 0 ]] || die "Run this script with sudo or as root."
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}
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command_exists() {
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command -v "$1" >/dev/null 2>&1
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}
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#######################################
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# Sanity checks
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#######################################
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require_root
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if [[ -z "${TARGET_HOME}" || ! -d "${TARGET_HOME}" ]]; then
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die "Could not determine home directory for target user: ${TARGET_USER}"
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fi
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log "Starting Arch Kubernetes bootstrap"
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log "Target kubectl user: ${TARGET_USER}"
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log "Target home: ${TARGET_HOME}"
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#######################################
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# 1) Fully update Arch
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#######################################
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log "Updating package databases and upgrading system"
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pacman -Syu --noconfirm
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#######################################
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# 2) Install required packages
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#
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# Important:
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# - iptables-nft must replace legacy iptables in the SAME transaction.
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# - We intentionally do not remove iptables first because that can break
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# dependency resolution temporarily for packages that need libxtables.
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#######################################
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log "Installing container runtime, Kubernetes tools, networking tools, and iptables-nft"
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yes | pacman -S --needed \
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ca-certificates \
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curl \
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wget \
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containerd \
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crictl \
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kubelet \
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kubeadm \
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kubectl \
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conntrack-tools \
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socat \
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ethtool \
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cni-plugins \
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iptables-nft
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#######################################
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# 3) Verify iptables backend
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#######################################
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log "Verifying iptables backend"
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iptables --version || true
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#######################################
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# 4) Enable and configure containerd
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#
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# kubelet works best with containerd configured to use systemd cgroups.
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#######################################
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log "Enabling and starting containerd"
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systemctl enable --now containerd.service
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log "Creating default containerd config if missing"
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mkdir -p /etc/containerd
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if [[ ! -f /etc/containerd/config.toml ]]; then
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containerd config default > /etc/containerd/config.toml
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fi
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log "Setting SystemdCgroup = true in /etc/containerd/config.toml"
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sed -i 's/SystemdCgroup = false/SystemdCgroup = true/' /etc/containerd/config.toml
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log "Restarting containerd to apply config"
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systemctl restart containerd.service
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#######################################
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# 5) Load required kernel modules now and on boot
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#######################################
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log "Persisting required kernel modules"
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cat > /etc/modules-load.d/k8s.conf <<'EOF'
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overlay
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br_netfilter
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EOF
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log "Loading kernel modules immediately"
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modprobe overlay
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modprobe br_netfilter
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#######################################
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# 6) Apply required sysctl settings now and on boot
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#######################################
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log "Persisting required sysctl settings"
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cat > /etc/sysctl.d/k8s.conf <<'EOF'
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net.bridge.bridge-nf-call-iptables = 1
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net.bridge.bridge-nf-call-ip6tables = 1
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net.ipv4.ip_forward = 1
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EOF
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log "Applying sysctl settings"
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sysctl --system
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#######################################
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# 7) Disable swap now and comment swap entries in /etc/fstab
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#######################################
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log "Disabling swap immediately"
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swapoff -a || true
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log "Commenting active swap entries in /etc/fstab"
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if [[ -f /etc/fstab ]]; then
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cp /etc/fstab /etc/fstab.bak.$(date +%s)
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sed -i '/^[^#].*\sswap\s/s/^/# /' /etc/fstab
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fi
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#######################################
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# 8) Enable kubelet
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#
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# kubelet may show as active but waiting until kubeadm init finishes; that is
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# normal before the control plane exists.
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#######################################
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log "Enabling and starting kubelet"
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systemctl enable --now kubelet.service
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#######################################
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# 9) Preflight visibility
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#######################################
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log "Container runtime status"
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systemctl --no-pager --full status containerd.service || true
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log "Kubelet status"
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systemctl --no-pager --full status kubelet.service || true
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#######################################
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# 10) Initialize cluster if not already initialized
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#######################################
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if [[ ! -f /etc/kubernetes/admin.conf ]]; then
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log "Initializing Kubernetes control plane with kubeadm"
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kubeadm init --pod-network-cidr="${POD_CIDR}"
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else
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log "Skipping kubeadm init because /etc/kubernetes/admin.conf already exists"
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fi
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#######################################
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# 11) Configure kubectl for target user
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#######################################
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log "Configuring kubectl for ${TARGET_USER}"
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mkdir -p "${TARGET_HOME}/.kube"
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cp -f /etc/kubernetes/admin.conf "${TARGET_HOME}/.kube/config"
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chown -R "${TARGET_USER}:${TARGET_USER}" "${TARGET_HOME}/.kube"
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chmod 700 "${TARGET_HOME}/.kube"
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chmod 600 "${TARGET_HOME}/.kube/config"
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#######################################
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# 12) Wait briefly for API server to become responsive
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#######################################
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log "Waiting for Kubernetes API to become reachable"
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for _ in $(seq 1 60); do
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if sudo -u "${TARGET_USER}" kubectl --kubeconfig="${TARGET_HOME}/.kube/config" get nodes >/dev/null 2>&1; then
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break
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fi
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sleep 2
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done
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#######################################
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# 13) Install Flannel if not already present
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#######################################
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log "Installing Flannel CNI"
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if ! sudo -u "${TARGET_USER}" kubectl --kubeconfig="${TARGET_HOME}/.kube/config" get namespace kube-flannel >/dev/null 2>&1; then
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sudo -u "${TARGET_USER}" kubectl --kubeconfig="${TARGET_HOME}/.kube/config" apply -f "${FLANNEL_MANIFEST_URL}"
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else
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log "kube-flannel namespace already exists; skipping Flannel install"
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fi
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#######################################
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# 14) Optionally allow scheduling on single-node control plane
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#######################################
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if [[ "${ALLOW_PODS_ON_CONTROL_PLANE}" == "true" ]]; then
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log "Allowing workloads on the control-plane node (single-node lab mode)"
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sudo -u "${TARGET_USER}" kubectl --kubeconfig="${TARGET_HOME}/.kube/config" taint nodes --all node-role.kubernetes.io/control-plane- || true
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else
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log "Leaving default control-plane taint in place"
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fi
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#######################################
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# 15) Final status / useful commands
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#######################################
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log "Final checks"
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echo
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echo "==== iptables backend ===="
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iptables --version || true
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echo
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echo "==== containerd info ===="
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crictl info >/dev/null 2>&1 && echo "crictl can talk to the runtime" || echo "crictl check did not succeed yet"
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echo
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echo "==== nodes ===="
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sudo -u "${TARGET_USER}" kubectl --kubeconfig="${TARGET_HOME}/.kube/config" get nodes -o wide || true
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echo
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echo "==== pods (all namespaces) ===="
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sudo -u "${TARGET_USER}" kubectl --kubeconfig="${TARGET_HOME}/.kube/config" get pods -A -o wide || true
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cat <<EOF
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Bootstrap complete.
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kubectl is configured for:
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user: ${TARGET_USER}
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config: ${TARGET_HOME}/.kube/config
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Common next commands:
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kubectl get nodes
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kubectl get pods -A
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kubectl cluster-info
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If the node is not Ready yet, wait a minute and re-run:
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kubectl get nodes
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kubectl get pods -A
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To test the cluster:
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kubectl create deployment nginx --image=nginx
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kubectl expose deployment nginx --port=80 --type=NodePort
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kubectl get svc
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To join worker nodes later, generate a join command with:
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kubeadm token create --print-join-command
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EOF |