#!/bin/bash
set -e

# This script is part of my blog post : 
# http://thoughtsimproved.wordpress.com/2015/01/03/tech-recipe-setup-a-rabbitmq-cluster-on-ubuntu/ 

# It sets up a RabbitMQ cluster by connecting to user-provided master and slave servers 
# and ringing them up to a cluster on the fly.

# RabbitMQ Clustering is described in detail here :
# https://www.rabbitmq.com/clustering.html


function getHostname()
{
	local HOST=''

	while test -z "$HOST"
	do
	  read -p "$1 : " HOST
	done

	echo $HOST;
}

SETUP_MASTER_SCRIPT='
sudo rabbitmqctl stop_app;
sudo rabbitmqctl reset;
sudo rabbitmqctl start_app;
';

# Step 1 : Setup the Master and get the erlang cookie

echo "Setup RabbitMQ Master";
echo "=====================";

OUT=/tmp/master.out
MASTER_HOSTNAME=$(getHostname "Enter the master server's hostname [hostname or user@hostname]");
echo "[$MASTER_HOSTNAME] Setting up master";
ssh -t $MASTER_HOSTNAME "bash -c '$SETUP_MASTER_SCRIPT sudo cat /var/lib/rabbitmq/.erlang.cookie;'" | tee $OUT;
COOKIE=$(cat $OUT | tail -n1)
rm $OUT;
echo "Master's Erlang Cookie : '$COOKIE'"

MASTER_IP=$(getHostname "Enter the master server's IP as seen from the slaves (Use a local IP if available)");


# Step 3 : Setup the slaves

SETUP_SLAVE_SCRIPT="
sudo sed -i \"s/^$/$MASTER_IP    $MASTER_HOSTNAME\n/\" /etc/hosts
sudo bash -c \"echo -n '$COOKIE' > /var/lib/rabbitmq/.erlang.cookie\";
sudo rabbitmqctl stop_app;
sudo rabbitmqctl reset;
sudo rabbitmqctl join_cluster --ram rabbit@$MASTER_HOSTNAME;
sudo rabbitmqctl start_app;
sudo rabbitmqctl cluster_status;
";

echo "Setup RabbitMQ Slaves";
echo "=====================";

S="Enter the server's hostname [hostname or user@hostname] or 'q' to quit : "
SERVER=$(getHostname $S);
while test "$SERVER" != "q"
do
	echo "[SERVER] Setting up slave";
	ssh -t $SERVER "bash -c '$SETUP_SLAVE_SCRIPT'";
	SERVER=$(getHostname $S);
done

echo "Done";