dynamic haproxy

#!/usr/bin/env bash

: ${HAPROXY_PATCHED:=/etc/haproxy/haproxy.cfg.auto-scaling}
: ${HAPROXY_TEMPLATE:=/etc/haproxy/haproxy.cfg.auto-scaling.template}
: ${MARFEEL_AUTOSCALING_GROUP:=marfeelcandidate4-auto-scaling-group}

: ${HAPROXY:=/usr/sbin/haproxy}

yell() { echo -e "$0: $*" >&2; }
die() { yell "$*"; exit 1; }
die_and_yell() { yell "$1"; exit $2; }
try() { "$@" || die "cannot $*"; }

if (( $# != 1 )); then
        die "Wrong number of arguments: $0 + final haproxy.cfg file\n\n - You can also set some environment variables, like MARFEEL_AUTOSCALING_GROUP, check the man page"
fi

HAPROXY_CFG=$1;
HAPROXY_CFG_DIR=`dirname ${HAPROXY_CFG}`

if [ -e ${HAPROXY_CFG_DIR} ]; then
        cp ${HAPROXY_TEMPLATE} ${HAPROXY_PATCHED}
        #for i in `aws autoscaling describe-auto-scaling-groups --auto-scaling-group-name marfeelcandidate4-auto-scaling-group | grep INSTANCES | awk '{ print $4}'`; do aws ec2 describe-instances --instance-ids $i | grep ASSOCIATION | awk '{ print $4 }' | head -1; done | xargs -L 1 -I IP sed -i "0,/autoscale_ip/s//IP/" ${HAPROXY_PATCHED}
        for i in `aws autoscaling describe-auto-scaling-groups --auto-scaling-group-name marfeelcandidate4-auto-scaling-group | grep INSTANCES | awk '{ print $4}'`; do aws ec2 describe-instances --instance-ids $i | grep ASSOCIATION | awk '{ print $4 }' | head -1; done | xargs -L 1 -I IP echo "   server marfeel-candidate-4-webserver IP:80/ check" >> ${HAPROXY_PATCHED}
        if [[ $? == 0 ]]; then
                ${HAPROXY} -c -f ${HAPROXY_PATCHED} -q
                if [[ $? == 0 ]]; then
                        cp ${HAPROXY_PATCHED} ${HAPROXY_CFG}
                        /etc/init.d/haproxy restart
                        if [[ $? != 0 ]]; then
                                die "Panic, check what happened"
                        fi
                        echo "haproxy restarted"
                        # some housekeeping, remove the temporal patched file
                        rm ${HAPROXY_PATCHED}
                else
                        echo "HOLA"
                        die "Wrong ${HAPROXY_PATCHED} syntax, please check it"
                fi
                exit 0
        else
                die "Problem patching the ${HAPROXY_TEMPLATE} file."
        fi
fi

die "Something went wrong"