Add host readiness checker for Matrix/Conduit deployment (#166)

Pre-flight validation script that tests Docker, ports, DNS, disk,
and memory before running deploy-matrix.sh.

infra/matrix/host-readiness-check.sh

@@ -0,0 +1,124 @@
+#!/usr/bin/env bash
+# host-readiness-check.sh — Validate target host before Matrix/Conduit deployment
+# Usage: ./host-readiness-check.sh [DOMAIN]
+# Issue: #166 / #183
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+DOMAIN="${1:-${MATRIX_DOMAIN:-}}"
+
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+NC='\033[0m'
+
+PASS=0
+FAIL=0
+WARN=0
+
+pass() { echo -e "${GREEN}[PASS]${NC} $*"; ((PASS++)); }
+fail() { echo -e "${RED}[FAIL]${NC} $*"; ((FAIL++)); }
+warn() { echo -e "${YELLOW}[WARN]${NC} $*"; ((WARN++)); }
+
+log() { echo -e "\n==> $*"; }
+
+log "Matrix/Conduit Host Readiness Check"
+log "===================================="
+
+# === Domain check ===
+if [[ -z "$DOMAIN" ]]; then
+    fail "DOMAIN not specified. Usage: ./host-readiness-check.sh matrix.timmytime.net"
+    exit 1
+else
+    pass "Domain specified: $DOMAIN"
+fi
+
+# === Docker ===
+log "Checking Docker..."
+if command -v docker &>/dev/null; then
+    DOCKER_VER=$(docker --version)
+    pass "Docker installed: $DOCKER_VER"
+else
+    fail "Docker not installed"
+fi
+
+if docker compose version &>/dev/null || docker-compose --version &>/dev/null; then
+    pass "Docker Compose available"
+else
+    fail "Docker Compose not available"
+fi
+
+if docker info &>/dev/null; then
+    pass "Docker daemon is running"
+else
+    fail "Docker daemon is not running or user lacks permissions"
+fi
+
+# === Ports ===
+log "Checking ports..."
+for port in 80 443 8448; do
+    if ss -tln | grep -q ":$port "; then
+        warn "Port $port is already in use (may conflict)"
+    else
+        pass "Port $port is available"
+    fi
+done
+
+# === DNS Resolution ===
+log "Checking DNS..."
+RESOLVED_IP=$(dig +short "$DOMAIN" || true)
+if [[ -n "$RESOLVED_IP" ]]; then
+    HOST_IP=$(curl -s ifconfig.me || true)
+    if [[ "$RESOLVED_IP" == "$HOST_IP" ]]; then
+        pass "DNS A record resolves to this host ($HOST_IP)"
+    else
+        warn "DNS A record resolves to $RESOLVED_IP (this host is $HOST_IP)"
+    fi
+else
+    fail "DNS A record for $DOMAIN not found"
+fi
+
+# === Disk Space ===
+log "Checking disk space..."
+AVAILABLE_GB=$(df -BG "$SCRIPT_DIR" | awk 'NR==2 {gsub(/G/,""); print $4}')
+if [[ "$AVAILABLE_GB" -ge 20 ]]; then
+    pass "Disk space: ${AVAILABLE_GB}GB available"
+else
+    warn "Disk space: ${AVAILABLE_GB}GB available (recommended: 20GB+)"
+fi
+
+# === Memory ===
+log "Checking memory..."
+MEM_GB=$(free -g | awk '/^Mem:/ {print $2}')
+if [[ "$MEM_GB" -ge 2 ]]; then
+    pass "Memory: ${MEM_GB}GB"
+else
+    warn "Memory: ${MEM_GB}GB (recommended: 2GB+)"
+fi
+
+# === Reverse proxy detection ===
+log "Checking reverse proxy..."
+if command -v caddy &>/dev/null; then
+    pass "Caddy installed"
+elif command -v nginx &>/dev/null; then
+    pass "Nginx installed"
+elif ss -tln | grep -q ":80 " || ss -tln | grep -q ":443 "; then
+    warn "No Caddy/Nginx found, but something is bound to 80/443"
+else
+    warn "No reverse proxy detected (Caddy or Nginx recommended)"
+fi
+
+# === Summary ===
+log "===================================="
+echo -e "Results: ${GREEN}$PASS passed${NC}, ${YELLOW}$WARN warnings${NC}, ${RED}$FAIL failures${NC}"
+
+if [[ $FAIL -gt 0 ]]; then
+    echo ""
+    echo "Host is NOT ready for deployment. Fix failures above, then re-run."
+    exit 1
+else
+    echo ""
+    echo "Host looks ready. Next step: ./deploy-matrix.sh $DOMAIN"
+    exit 0
+fi