#!/bin/sh

# 37-host-optimization.sh: Detect ARP flux sysctl configuration.
#
# This script does not change host/kernel settings.

YELLOW=$(printf '\033[1;33m')
RESET=$(printf '\033[0m')

failed=0

[ "$(sysctl -n net.ipv4.conf.all.arp_ignore 2>/dev/null || echo unknown)" = "1" ] || failed=1
[ "$(sysctl -n net.ipv4.conf.all.arp_announce 2>/dev/null || echo unknown)" = "2" ] || failed=1

if [ "$failed" -eq 1 ]; then
    >&2 printf "%s" "${YELLOW}"
    >&2 cat <<'EOF'
══════════════════════════════════════════════════════════════════════════════
⚠️  WARNING: ARP flux sysctls are not set.

    Expected values:
      net.ipv4.conf.all.arp_ignore=1
      net.ipv4.conf.all.arp_announce=2

    Note: If using 'network_mode: host', setting these via docker-compose sysctls
    requires the NET_ADMIN capability. When granted, these sysctls will
    modify the host namespace. Otherwise, you must configure them directly
    on your host operating system instead.

    Detection accuracy may be reduced until configured.

    See: https://docs.netalertx.com/docker-troubleshooting/arp-flux-sysctls/
══════════════════════════════════════════════════════════════════════════════
EOF
    >&2 printf "%s" "${RESET}"
fi