alpine/rootfs-extra/opt/scripts/bootstrap-control-plane.sh
raw ยท 10675 bytes
#!/bin/sh
set -eu
CONFIG_DIR="${CONFIG_DIR:-/opt/monok8s/config}"
CLUSTER_ENV="${CONFIG_DIR}/cluster.env"
KUBEADM_CONFIG_OUT="${KUBEADM_CONFIG_OUT:-/tmp/kubeadm-init.yaml}"
log() {
echo "[monok8s] $*"
}
fail() {
echo "[monok8s] ERROR: $*" >&2
exit 1
}
need_cmd() {
command -v "$1" >/dev/null 2>&1 || fail "missing required command: $1"
}
require_file() {
[ -f "$1" ] || fail "required file not found: $1"
}
load_config() {
require_file "$CLUSTER_ENV"
# shellcheck disable=SC1090
. "$CLUSTER_ENV"
: "${KUBERNETES_VERSION:?KUBERNETES_VERSION is required}"
: "${NODE_NAME:?NODE_NAME is required}"
: "${APISERVER_ADVERTISE_ADDRESS:?APISERVER_ADVERTISE_ADDRESS is required}"
POD_SUBNET="${POD_SUBNET:-10.244.0.0/16}"
SERVICE_SUBNET="${SERVICE_SUBNET:-10.96.0.0/12}"
CLUSTER_NAME="${CLUSTER_NAME:-monok8s}"
CLUSTER_DOMAIN="${CLUSTER_DOMAIN:-cluster.local}"
CONTAINER_RUNTIME_ENDPOINT="${CONTAINER_RUNTIME_ENDPOINT:-unix:///var/run/crio/crio.sock}"
SANS="${SANS:-}"
ALLOW_SCHEDULING_ON_CONTROL_PLANE="${ALLOW_SCHEDULING_ON_CONTROL_PLANE:-yes}"
SKIP_IMAGE_CHECK="${SKIP_IMAGE_CHECK:-no}"
KUBECONFIG_USER_HOME="${KUBECONFIG_USER_HOME:-/root}"
}
check_prereqs() {
need_cmd kubeadm
need_cmd kubelet
need_cmd kubectl
need_cmd crictl
need_cmd rc-service
need_cmd awk
need_cmd grep
need_cmd sed
need_cmd hostname
[ -S /var/run/crio/crio.sock ] || fail "CRI-O socket not found at /var/run/crio/crio.sock"
}
set_hostname_if_needed() {
current_hostname="$(hostname 2>/dev/null || true)"
if [ "$current_hostname" != "$NODE_NAME" ]; then
log "setting hostname to $NODE_NAME"
hostname "$NODE_NAME"
mkdir -p /etc
printf '%s\n' "$NODE_NAME" > /etc/hostname
# Keep localhost mapping sane even without DNS.
if [ -f /etc/hosts ]; then
if ! grep -Eq "[[:space:]]$NODE_NAME([[:space:]]|\$)" /etc/hosts; then
printf '127.0.0.1\tlocalhost %s\n' "$NODE_NAME" >> /etc/hosts
fi
else
cat > /etc/hosts <<EOF
127.0.0.1 localhost $NODE_NAME
EOF
fi
fi
}
ensure_ip_forward() {
current="$(cat /proc/sys/net/ipv4/ip_forward 2>/dev/null || echo 0)"
if [ "$current" != "1" ]; then
log "enabling IPv4 forwarding"
echo 1 > /proc/sys/net/ipv4/ip_forward
fi
mkdir -p /etc/sysctl.d
cat > /etc/sysctl.d/99-monok8s.conf <<'EOF'
net.ipv4.ip_forward = 1
EOF
}
ensure_kubelet_binary() {
if command -v kubelet >/dev/null 2>&1; then
return 0
fi
if [ -x /usr/local/bin/kubelet ]; then
export PATH="/usr/local/bin:$PATH"
return 0
fi
if [ -x /opt/cni/bin/kubelet ]; then
export PATH="/opt/cni/bin:$PATH"
return 0
fi
fail "kubelet binary not found; install kubelet into /usr/local/bin or make sure PATH includes it"
}
ensure_kubelet_service() {
if ! rc-service kubelet status >/dev/null 2>&1; then
if [ ! -f /etc/init.d/kubelet ]; then
fail "kubelet OpenRC service does not exist at /etc/init.d/kubelet"
fi
log "starting kubelet service"
rc-service kubelet start || fail "failed to start kubelet"
fi
}
check_crio_running() {
log "checking CRI-O status..."
if ! rc-service crio status >/dev/null 2>&1; then
fail "crio service is not running"
fi
if ! crictl --runtime-endpoint "$CONTAINER_RUNTIME_ENDPOINT" info >/dev/null 2>&1; then
fail "crictl cannot talk to CRI-O via $CONTAINER_RUNTIME_ENDPOINT"
fi
log "CRI-O is up"
}
normalize_image_ref() {
# Add docker.io/library/ for bare images like pause:3.10 if needed.
# kubeadm usually emits full refs already, so this is just defensive.
ref="$1"
case "$ref" in
*/* ) echo "$ref" ;;
* ) echo "docker.io/library/$ref" ;;
esac
}
image_present() {
wanted="$1"
repo="${wanted%:*}"
tag="${wanted##*:}"
crictl --runtime-endpoint "$CONTAINER_RUNTIME_ENDPOINT" images \
| awk 'NR>1 { print $1 ":" $2 }' \
| grep -Fx "$repo:$tag" >/dev/null 2>&1
}
check_required_images() {
[ "$SKIP_IMAGE_CHECK" = "yes" ] && {
log "skipping image check (SKIP_IMAGE_CHECK=yes)"
return 0
}
log "checking required Kubernetes images for $KUBERNETES_VERSION..."
missing_any=0
for img in $(kubeadm config images list --kubernetes-version "$KUBERNETES_VERSION"); do
if image_present "$img"; then
log "found image: $img"
else
echo "[monok8s] MISSING image: $img" >&2
missing_any=1
fi
done
[ "$missing_any" -eq 0 ] || fail "preload the Kubernetes images before bootstrapping"
log "all required images are present"
}
check_node_name() {
current_hostname="$(hostname)"
if [ "$current_hostname" != "$NODE_NAME" ]; then
log "warning: hostname is '$current_hostname' but NODE_NAME is '$NODE_NAME'"
log "kubeadm will use NODE_NAME from config"
fi
}
check_already_initialized() {
if [ -f /etc/kubernetes/admin.conf ]; then
fail "cluster already appears initialized (/etc/kubernetes/admin.conf exists)"
fi
}
generate_kubeadm_config() {
log "generating kubeadm config at $KUBEADM_CONFIG_OUT..."
SAN_LINES=""
if [ -n "${SANS:-}" ]; then
old_ifs="$IFS"
IFS=','
for san in $SANS; do
san_trimmed="$(echo "$san" | sed 's/^ *//;s/ *$//')"
[ -n "$san_trimmed" ] && SAN_LINES="${SAN_LINES} - \"${san_trimmed}\"
"
done
IFS="$old_ifs"
fi
cat > "$KUBEADM_CONFIG_OUT" <<EOF
apiVersion: kubeadm.k8s.io/v1beta4
kind: InitConfiguration
localAPIEndpoint:
advertiseAddress: ${APISERVER_ADVERTISE_ADDRESS}
bindPort: 6443
nodeRegistration:
name: ${NODE_NAME}
criSocket: ${CONTAINER_RUNTIME_ENDPOINT}
imagePullPolicy: IfNotPresent
kubeletExtraArgs:
- name: hostname-override
value: "${NODE_NAME}"
- name: node-ip
value: "${APISERVER_ADVERTISE_ADDRESS}"
- name: pod-manifest-path
value: "/etc/kubernetes/manifests"
---
apiVersion: kubeadm.k8s.io/v1beta4
kind: ClusterConfiguration
clusterName: ${CLUSTER_NAME}
kubernetesVersion: ${KUBERNETES_VERSION}
networking:
podSubnet: ${POD_SUBNET}
serviceSubnet: ${SERVICE_SUBNET}
dnsDomain: ${CLUSTER_DOMAIN}
apiServer:
certSANs:
- "${APISERVER_ADVERTISE_ADDRESS}"
${SAN_LINES}---
apiVersion: kubelet.config.k8s.io/v1beta1
kind: KubeletConfiguration
cgroupDriver: cgroupfs
containerRuntimeEndpoint: ${CONTAINER_RUNTIME_ENDPOINT}
EOF
}
run_kubeadm_init() {
log "running kubeadm init..."
kubeadm init --config "$KUBEADM_CONFIG_OUT"
}
warn_dummy_interface() {
YELLOW="$(printf '\033[1;33m')"
RESET="$(printf '\033[0m')"
echo
printf '%s' "$YELLOW"
echo "[monok8s] WARNING: No suitable network interface found for API server address."
echo "[monok8s] Creating a temporary dummy interface for bootstrap."
echo "[monok8s] This configuration is intended for local/testing use only."
echo "[monok8s] Please configure a real network interface for production."
printf '%s' "$RESET"
echo
}
ensure_apiserver_address_present() {
: "${APISERVER_ADVERTISE_ADDRESS:?APISERVER_ADVERTISE_ADDRESS is required}"
DUMMY_IFACE="${DUMMY_IFACE:-dummy0}"
DUMMY_PREFIX_LEN="${DUMMY_PREFIX_LEN:-32}"
# If the address already exists on an interface, we're done.
if ip -o addr show | awk '{print $4}' | cut -d/ -f1 | grep -Fx "$APISERVER_ADVERTISE_ADDRESS" >/dev/null 2>&1; then
log "API server advertise address already present: $APISERVER_ADVERTISE_ADDRESS"
return 0
fi
warn_dummy_interface
if ! command -v modprobe >/dev/null 2>&1; then
fail "modprobe not found; cannot create dummy interface"
fi
log "loading dummy kernel module..."
modprobe dummy || fail "failed to load dummy kernel module"
if ! ip link show "$DUMMY_IFACE" >/dev/null 2>&1; then
log "creating dummy interface: $DUMMY_IFACE"
ip link add "$DUMMY_IFACE" type dummy || fail "failed to create dummy interface $DUMMY_IFACE"
else
log "dummy interface already exists: $DUMMY_IFACE"
fi
log "assigning ${APISERVER_ADVERTISE_ADDRESS}/${DUMMY_PREFIX_LEN} to $DUMMY_IFACE"
ip addr add "${APISERVER_ADVERTISE_ADDRESS}/${DUMMY_PREFIX_LEN}" dev "$DUMMY_IFACE" 2>/dev/null || true
log "bringing up $DUMMY_IFACE"
ip link set "$DUMMY_IFACE" up || fail "failed to bring up $DUMMY_IFACE"
if ! ip -o addr show dev "$DUMMY_IFACE" | awk '{print $4}' | cut -d/ -f1 | grep -Fx "$APISERVER_ADVERTISE_ADDRESS" >/dev/null 2>&1; then
fail "dummy interface came up, but ${APISERVER_ADVERTISE_ADDRESS} is still not present"
fi
log "dummy interface ready: $DUMMY_IFACE -> ${APISERVER_ADVERTISE_ADDRESS}/${DUMMY_PREFIX_LEN}"
}
setup_local_kubectl() {
kube_dir="${KUBECONFIG_USER_HOME}/.kube"
log "setting up local kubectl config in ${kube_dir}/config..."
mkdir -p "$kube_dir"
cp /etc/kubernetes/admin.conf "${kube_dir}/config"
chmod 600 "${kube_dir}/config"
if [ "$KUBECONFIG_USER_HOME" = "/root" ]; then
mkdir -p /etc/profile.d
cat > /etc/profile.d/kubeconfig.sh <<'EOF'
export KUBECONFIG=/root/.kube/config
EOF
chmod 644 /etc/profile.d/kubeconfig.sh
fi
}
allow_single_node_scheduling() {
if [ "$ALLOW_SCHEDULING_ON_CONTROL_PLANE" != "yes" ]; then
log "leaving control-plane taint in place"
return 0
fi
log "removing control-plane taint so this single node can schedule workloads..."
kubectl --kubeconfig /etc/kubernetes/admin.conf taint nodes "$NODE_NAME" node-role.kubernetes.io/control-plane- >/dev/null 2>&1 || true
}
print_next_steps() {
cat <<EOF
[monok8s] bootstrap complete
Try these now:
export KUBECONFIG=/root/.kube/config
kubectl get nodes -o wide
kubectl describe nodes
Notes:
- On a fresh single-node control plane, the node may stay NotReady until you install a CNI.
- 'kubectl describe nodes' will still work as soon as the API server is up and your kubeconfig is installed.
- If you want pods to run on this same node, keep ALLOW_SCHEDULING_ON_CONTROL_PLANE=yes.
EOF
}
main() {
load_config
set_hostname_if_needed
ensure_ip_forward
ensure_apiserver_address_present
check_prereqs
check_already_initialized
check_crio_running
check_required_images
generate_kubeadm_config
run_kubeadm_init
rc-service kubelet restart
setup_local_kubectl
allow_single_node_scheduling
print_next_steps
}
main "$@"