Add Alpine support and improve Tailscale install

Detect Alpine inside the LXC container and install Tailscale via apk (add community repo if missing), enable/start the service. Preserve Debian/Ubuntu install path but improve DNS resolution checks, temporarily override /etc/resolv.conf if DNS appears blocked, and restore it afterwards. Switch pct exec to use sh -c, tighten command existence checks and redirections, ensure curl and keyring directory are present, add Tailscale apt source and install package. Overall robustness and error-handling improvements for installing Tailscale in containers.

tools/addon/add-tailscale-lxc.sh

@@ -76,12 +76,33 @@ grep -q "lxc.mount.entry: /dev/net/tun" "$CTID_CONFIG_PATH" || echo "lxc.mount.e
 header_info
 msg_info "Installing Tailscale in CT $CTID"
 
-pct exec "$CTID" -- bash -c '
+pct exec "$CTID" -- sh -c '
 set -e
+
+# Detect OS inside container
+if [ -f /etc/alpine-release ]; then
+  # ── Alpine Linux ──
+  echo "[INFO] Alpine Linux detected, installing Tailscale via apk..."
+
+  # Enable community repo if not already enabled
+  if ! grep -q "^[^#].*community" /etc/apk/repositories 2>/dev/null; then
+    ALPINE_VERSION=$(cat /etc/alpine-release | cut -d. -f1,2)
+    echo "https://dl-cdn.alpinelinux.org/alpine/v${ALPINE_VERSION}/community" >> /etc/apk/repositories
+  fi
+
+  apk update
+  apk add --no-cache tailscale
+
+  # Enable and start Tailscale service
+  rc-update add tailscale default 2>/dev/null || true
+  rc-service tailscale start 2>/dev/null || true
+
+else
+  # ── Debian / Ubuntu ──
   export DEBIAN_FRONTEND=noninteractive
 
   # Source os-release properly (handles quoted values)
-source /etc/os-release
+  . /etc/os-release
 
   # Fallback if DNS is poisoned or blocked
   ORIG_RESOLV="/etc/resolv.conf"
@@ -89,20 +110,20 @@ BACKUP_RESOLV="/tmp/resolv.conf.backup"
 
   # Check DNS resolution using multiple methods (dig may not be installed)
   dns_check_failed=true
-if command -v dig &>/dev/null; then
+  if command -v dig >/dev/null 2>&1; then
     if dig +short pkgs.tailscale.com 2>/dev/null | grep -qvE "^127\.|^0\.0\.0\.0$|^$"; then
       dns_check_failed=false
     fi
-elif command -v host &>/dev/null; then
+  elif command -v host >/dev/null 2>&1; then
     if host pkgs.tailscale.com 2>/dev/null | grep -q "has address"; then
       dns_check_failed=false
     fi
-elif command -v nslookup &>/dev/null; then
+  elif command -v nslookup >/dev/null 2>&1; then
     if nslookup pkgs.tailscale.com 2>/dev/null | grep -q "Address:"; then
       dns_check_failed=false
     fi
-elif command -v getent &>/dev/null; then
-  if getent hosts pkgs.tailscale.com &>/dev/null; then
+  elif command -v getent >/dev/null 2>&1; then
+    if getent hosts pkgs.tailscale.com >/dev/null 2>&1; then
       dns_check_failed=false
     fi
   else
@@ -117,11 +138,10 @@ if $dns_check_failed; then
     echo "nameserver 1.1.1.1" >"$ORIG_RESOLV"
   fi
 
-if ! command -v curl &>/dev/null; then
+  if ! command -v curl >/dev/null 2>&1; then
     echo "[INFO] curl not found, installing..."
     apt-get update -qq
- apt update -qq
- apt install -y curl >/dev/null
+    apt-get install -y curl >/dev/null
   fi
 
   # Ensure keyrings directory exists
@@ -134,13 +154,13 @@ echo "deb [signed-by=/usr/share/keyrings/tailscale-archive-keyring.gpg] https://
     >/etc/apt/sources.list.d/tailscale.list
 
   apt-get update -qq
-apt update -qq
-apt install -y tailscale >/dev/null
+  apt-get install -y tailscale >/dev/null
 
-if [[ -f /tmp/resolv.conf.backup ]]; then
+  if [ -f /tmp/resolv.conf.backup ]; then
     echo "[INFO] Restoring original /etc/resolv.conf"
     mv /tmp/resolv.conf.backup /etc/resolv.conf
   fi
+fi
 '
 
 TAGS=$(awk -F': ' '/^tags:/ {print $2}' "$CTID_CONFIG_PATH")