entrypoint.sh

#!/bin/sh

set -exo pipefail

if [ "$#" -eq 0 ] || [ "${1#-}" != "$1" ]; then
  set -- nats-server "$@"
fi

# Enable jetstream if the env var is set
if ! [ -z "$NATS_JETSTREAM" ]; then
  cat << EOF >> /etc/nats/nats-server.conf
# Enable JetStream
jetstream {
  store_dir = /data/jetstream
}
EOF
fi

# If we're running in Fly, enable clustering and ensure the hostname is set
if ! [ -z "$FLY_APP_NAME" ]; then
  export HOSTNAME=$FLY_MACHINE_ID

  cat << EOF >> /etc/nats/nats-server.conf
# Advertise our machine's DNS name
client_advertise = ${FLY_ALLOC_ID}.vm.${FLY_APP_NAME}.internal:4222

# Enable clustering
cluster {
  name = ${FLY_APP_NAME}

  # Route connections to be received on any interface on port 6222
  host = ::
  port = 6222

  # Advertise our machine's DNS name
  cluster_advertise = ${FLY_ALLOC_ID}.vm.${FLY_APP_NAME}.internal:6222

  # Routes are actively solicited and connected to from this server
  routes = [
EOF

  local_ip=$(dig +short AAAA $FLY_ALLOC_ID.vm.$FLY_APP_NAME.internal)

  # Add all routes except our own
  for route in $(dig +short AAAA top3.nearest.of.$FLY_APP_NAME.internal); do
    if [ "$route" != "$local_ip" ]; then
      echo "    \"nats://[$route]:6222\"" >> /etc/nats/nats-server.conf
    fi
  done

  echo -e "  ]\n}" >> /etc/nats/nats-server.conf
fi

exec "$@"