What boots on first power-on

Bake this into your kldload image

#!/bin/bash
# postinstall-xmpp.sh — complete XMPP cluster, ready on first boot
set -euo pipefail

# ── Configuration (baked at build time or from env) ──
EJAB_DOMAIN="${EJAB_DOMAIN:-chat.example.com}"
ADMIN_USER="admin"
ADMIN_PASS="${ADMIN_PASS:-$(tr -dc A-Za-z0-9 </dev/urandom | head -c 24)}"
DB_NAME="ejabberd_db"
DB_USER="ejabberd_user"
DB_PASS="$(tr -dc A-Za-z0-9 </dev/urandom | head -c 32)"
CF_EMAIL="${CF_API_EMAIL:-}"
CF_KEY="${CF_API_KEY:-}"

# ── Install packages ──
kpkg install ejabberd nginx certbot python3-certbot-dns-cloudflare \
    postgresql postgresql-contrib \
    erlang-base erlang-dev

# ── PostgreSQL ──
systemctl enable --now postgresql

sudo -u postgres psql <<SQL
CREATE USER ${DB_USER} WITH ENCRYPTED PASSWORD '${DB_PASS}';
CREATE DATABASE ${DB_NAME} OWNER ${DB_USER};
SQL

# For clustering — enable streaming replication
PG_CONF="/etc/postgresql/*/main/postgresql.conf"
sed -i "s/^#listen_addresses.*/listen_addresses = '*'/" $PG_CONF
sed -i "s/^#wal_level.*/wal_level = replica/" $PG_CONF
sed -i "s/^#max_wal_senders.*/max_wal_senders = 10/" $PG_CONF
systemctl restart postgresql

# ── ejabberd configuration ──
cat > /etc/ejabberd/ejabberd.yml <<YAML
hosts:
  - "${EJAB_DOMAIN}"

auth_method: sql
sql_type: pgsql
sql_server: "127.0.0.1"
sql_database: "${DB_NAME}"
sql_username: "${DB_USER}"
sql_password: "${DB_PASS}"

listen:
  - port: 5222
    module: ejabberd_c2s
    starttls: true
    max_stanza_size: 262144
  - port: 5269
    module: ejabberd_s2s_in
    tls: true
  - port: 5280
    module: ejabberd_http
    request_handlers:
      "/admin": ejabberd_web_admin
      "/websocket": ejabberd_http_ws
      "/bosh": mod_bosh
  - port: 5281
    module: ejabberd_http
    request_handlers:
      "/api": mod_http_api

modules:
  mod_mam:
    db_type: sql
    default: always
  mod_muc:
    access_create: muc_create
    default_room_options:
      mam: true
      public: true
  mod_http_upload:
    put_url: "https://@HOST@:5443/upload"
  mod_push: {}
  mod_push_keepalive: {}
  mod_roster:
    versioning: true
  mod_stream_mgmt:
    resend_on_timeout: if_offline
YAML

# ── TLS certificate (Cloudflare DNS challenge) ──
if [[ -n "$CF_EMAIL" && -n "$CF_KEY" ]]; then
  mkdir -p /root/.secrets
  cat > /root/.secrets/cf.ini <<CF
dns_cloudflare_email = ${CF_EMAIL}
dns_cloudflare_api_key = ${CF_KEY}
CF
  chmod 600 /root/.secrets/cf.ini

  certbot certonly --dns-cloudflare \
    --dns-cloudflare-credentials /root/.secrets/cf.ini \
    --non-interactive --agree-tos \
    -d "${EJAB_DOMAIN}" -m "${CF_EMAIL}"
fi

# ── NGINX reverse proxy ──
cat > /etc/nginx/sites-available/ejabberd <<NGX
server {
    listen 80;
    server_name ${EJAB_DOMAIN};
    return 301 https://\\\$host\\\$request_uri;
}
server {
    listen 443 ssl;
    server_name ${EJAB_DOMAIN};
    ssl_certificate /etc/letsencrypt/live/${EJAB_DOMAIN}/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/${EJAB_DOMAIN}/privkey.pem;

    location /admin { proxy_pass https://localhost:5280/admin; }
    location /ws/ {
        proxy_pass http://127.0.0.1:5280/ws/;
        proxy_http_version 1.1;
        proxy_set_header Upgrade \\\$http_upgrade;
        proxy_set_header Connection "upgrade";
    }
}
NGX
ln -sf /etc/nginx/sites-available/ejabberd /etc/nginx/sites-enabled/
systemctl enable --now nginx

# ── Start ejabberd and create admin ──
systemctl enable --now ejabberd
sleep 5
ejabberdctl register "${ADMIN_USER}" "${EJAB_DOMAIN}" "${ADMIN_PASS}"

# ── Auto-renew certs ──
echo "0 2 * * * root certbot renew --quiet && systemctl reload nginx ejabberd" \
    > /etc/cron.d/cert-renew

# ── Snapshot the working state ──
ksnap

echo "XMPP ready at ${EJAB_DOMAIN}"
echo "Admin: ${ADMIN_USER}@${EJAB_DOMAIN} / ${ADMIN_PASS}"

Scale from 1 to N nodes

# Node 1 is already running (the postinstall above)
# For nodes 2-N, add this to their postinstall:

# Point PostgreSQL to the master (node 1)
DB_HOST="10.100.10.101"  # node 1's IP

# After ejabberd starts, join the cluster
ejabberdctl join_cluster "ejabberd@node-1.example.com"

# That's it. ejabberd handles message routing between nodes.
# Users connected to node-2 can message users on node-1.
# MUC rooms span all nodes. MAM archive is shared via PostgreSQL.

PostgreSQL replication for the database

# On master (node 1) — already configured by postinstall
# wal_level=replica, max_wal_senders=10

# Create replication user
sudo -u postgres psql -c \
  "CREATE USER replicator WITH REPLICATION ENCRYPTED PASSWORD 'replpass';"

# On replica (node 2)
systemctl stop postgresql
rm -rf /var/lib/postgresql/*/main/*
pg_basebackup -h 10.100.10.101 -D /var/lib/postgresql/15/main \
  -U replicator -W --wal-method=stream
touch /var/lib/postgresql/15/main/standby.signal
systemctl start postgresql

# Replica is now streaming from master.
# If master dies, promote replica: pg_ctl promote