#!/usr/bin/env bash
set -euo pipefail
[[ $EUID -eq 0 ]] || { echo 'Run with sudo.' >&2; exit 1; }
[[ -f /etc/debian_version ]] || { echo 'This script targets Debian.' >&2; exit 1; }
apt-get update
apt-get install -y ca-certificates curl gnupg python3
command -v docker >/dev/null || { echo 'Install Docker Engine and the Compose plugin first: https://docs.docker.com/engine/install/debian/' >&2; exit 1; }
docker compose version
current=$(sysctl -n vm.max_map_count)
if (( current < 262144 )); then
  printf 'vm.max_map_count=262144\n' > /etc/sysctl.d/90-host-metrics.conf
  sysctl -p /etc/sysctl.d/90-host-metrics.conf
fi
docker info >/dev/null
echo 'Host ready. Recommended: 4 vCPUs, 12 GiB RAM, 60+ GiB free SSD space.'