Test a .nmconnection keyfile with automatic rollback (companion to hetzner-nmconnection.sh)

test-nmconnection.sh

#!/usr/bin/env bash
# Test an .nmconnection keyfile and always revert. Writes result to /tmp/nm-test-result.
#
# Usage: ./test-nmconnection.sh <path-to.nmconnection>
#
# Designed to work with hetzner-nmconnection.sh:
#   ./hetzner-nmconnection.sh 12345 > static.nmconnection
#   ./test-nmconnection.sh static.nmconnection

set -euo pipefail

[[ ${1:-} ]] || { echo "usage: $0 <file.nmconnection>" >&2; exit 1; }
CONN_FILE="$1"
[[ -f $CONN_FILE ]] || { echo "error: $CONN_FILE not found" >&2; exit 1; }

CONN_NAME=$(awk -F= '/^id=/ {print $2; exit}' "$CONN_FILE")
[[ -n $CONN_NAME ]] || { echo "error: no id= found in $CONN_FILE" >&2; exit 1; }

ORIGINAL_CONN=$(nmcli -t -f NAME,DEVICE con show --active | head -1 | cut -d: -f1)
[[ -n $ORIGINAL_CONN ]] || { echo "error: no active connection to revert to" >&2; exit 1; }

BASENAME=$(basename "$CONN_FILE")
RESULT_FILE="/tmp/nm-test-result"

echo "testing '$CONN_NAME' from $CONN_FILE (revert to '$ORIGINAL_CONN')"

# -- rollback (always runs, survives SSH disconnect) --
nohup bash -c "
  sleep 15
  nmcli connection up '$ORIGINAL_CONN' 2>/dev/null
  nmcli connection delete '$CONN_NAME' 2>/dev/null
  rm -f /etc/NetworkManager/system-connections/$BASENAME
" > /dev/null 2>&1 &

# -- load and activate --
cp "$CONN_FILE" /etc/NetworkManager/system-connections/
chmod 600 /etc/NetworkManager/system-connections/"$BASENAME"
nmcli connection load /etc/NetworkManager/system-connections/"$BASENAME"
nmcli connection up "$CONN_NAME"

# -- test --
sleep 3
{
  echo "=== $(date) ==="
  echo "connection: $CONN_NAME"
  echo "ipv4: $(ping -c 2 -W 5 1.1.1.1 > /dev/null 2>&1 && echo PASS || echo FAIL)"
  echo "ipv6: $(ping -c 2 -W 5 2606:4700:4700::1111 > /dev/null 2>&1 && echo PASS || echo FAIL)"
  echo "dns:  $(ping -c 2 -W 5 cloudflare.com > /dev/null 2>&1 && echo PASS || echo FAIL)"
  ip addr show
  ip route show
} > "$RESULT_FILE" 2>&1

echo "results written to $RESULT_FILE, reverting in ~15s"