upstream-zulip/scripts/setup/generate-rabbitmq-cookie

#!/usr/bin/env bash
#
# rabbitmq sets an insecure "magic cookie" which is used for auth;
# reset it to be longer.
set -eu

cookiefile=/var/lib/rabbitmq/.erlang.cookie
# If the RabbitMQ distribution cookie is insecure, reset it
if [ ! -f "$cookiefile" ] || ! size="$(wc -c "$cookiefile")" || [ "${size%% *}" -le 20 ]; then
    running=0
    if service rabbitmq-server status >/dev/null; then
        running=1
        service rabbitmq-server stop
    fi

    echo "Setting a more secure RabbitMQ distribution magic cookie"
    cookie="$(LC_ALL=C tr -dc '[:alnum:]' </dev/urandom | head -c255)"
    [ "${#cookie}" -eq 255 ] # make sure tr wasn’t OOM-killed
    tmpfile="$(mktemp "$cookiefile.XXXXXXXXXX")"
    chown rabbitmq: "$tmpfile"
    printf '%s' "$cookie" >"$tmpfile"
    mv "$tmpfile" "$cookiefile"

    if [ "$running" == "1" ]; then
        service rabbitmq-server start
    fi
fi