Bash script to join a rabbitmq cluster of the same AWS autoscaling group

join_rabbitmq_cluster.sh

#!/bin/bash
wget --quiet http://s3.amazonaws.com/ec2metadata/ec2-metadata
sudo chmod u+x ec2-metadata
INSTANCE_ID=$(./ec2-metadata | grep instance-id | awk 'NR==1{print $2}')
AG_NAME=$(aws autoscaling describe-auto-scaling-instances --instance-ids ${INSTANCE_ID} --query AutoScalingInstances[].AutoScalingGroupName --output text)
echo ===================================
echo Searching for cluster in ${AG_NAME}
echo ===================================
echo Local Instance ID: ${INSTANCE_ID}
for ID in $(aws autoscaling describe-auto-scaling-groups --auto-scaling-group-names ${AG_NAME} --query AutoScalingGroups[].Instances[].InstanceId --output text);
do
    echo Found cluster node ${ID}
    if [ "${ID}" == ${INSTANCE_ID} ] ; then
        continue;
    fi
    DNS=$(aws ec2 describe-instances --instance-ids $ID --query Reservations[].Instances[].PrivateDnsName --output text)
    DNS=(${DNS//./ })
    echo Joining cluster ${ID} at rabbit@${DNS[0]}
    rabbitmqctl stop_app
    rabbitmqctl join_cluster rabbit@${DNS[0]}
    rabbitmqctl start_app
    exit 1
done

Note this is expecting your default region for the aws cli to already be set:

REGION=`/usr/bin/ec2metadata | grep "^availability-zone:" | awk '{print substr($2, 1, length($2)-1)}'`
aws configure set default.region $REGION