#!/usr/bin/env bash

# Join an additional K3s server (pi.knoe.org) to the existing cluster using k3sup.
# Default topology: HA embedded etcd with at least two servers.

set -euo pipefail

: "${K3S_EXISTING_SERVER_HOST:=raspberry.knoe.org}"
: "${K3S_EXISTING_SERVER_USER:=pi}"
: "${K3S_ADDITIONAL_SERVER_HOST:=pi.knoe.org}"
: "${K3S_ADDITIONAL_SERVER_USER:=pi}"
: "${K3S_SSH_KEY:=$HOME/.ssh/id_rsa}"
: "${K3S_VERSION:=}"

# You likely want your public name(s) here so clients can connect via hostname
# You may include multiple --tls-san by space-separating them.
K3S_EXTRA_ARGS_DEFAULT="--tls-san ${K3S_EXISTING_SERVER_HOST} --tls-san ${K3S_ADDITIONAL_SERVER_HOST}"
: "${K3S_EXTRA_ARGS:=${K3S_EXTRA_ARGS_DEFAULT}}"

echo "[info] Joining ${K3S_ADDITIONAL_SERVER_HOST} as additional K3s server to cluster at ${K3S_EXISTING_SERVER_HOST}"

if ! command -v k3sup >/dev/null 2>&1; then
  echo "[error] k3sup is not installed. See https://github.com/alexellis/k3sup" >&2
  exit 1
fi

K3SUP_ARGS=(join \
  --server \
  --ip "${K3S_ADDITIONAL_SERVER_HOST}" \
  --user "${K3S_ADDITIONAL_SERVER_USER}" \
  --ssh-key "${K3S_SSH_KEY}" \
  --server-ip "${K3S_EXISTING_SERVER_HOST}" \
  --server-user "${K3S_EXISTING_SERVER_USER}" \
  --k3s-extra-args "${K3S_EXTRA_ARGS}"
)

if [[ -n "${K3S_VERSION}" ]]; then
  K3SUP_ARGS+=(--k3s-version "${K3S_VERSION}")
fi

set -x
k3sup "${K3SUP_ARGS[@]}"
set +x

echo "[ok] ${K3S_ADDITIONAL_SERVER_HOST} joined as an additional K3s server"