Make shift HAproxy HA Monitor Upstart for Ubuntu 12.04 and 14.04

haproxy-ha.conf

# haproxy HA monitor

description "monitor the haproxy EIP for HA"

start on runlevel [2345]
stop on runlevel [!2345]
console log
limit nofile 65535 65535

respawn

# the haproxy instances will require the following IAM policy
# {
#  "Statement": [
#    {
#      "Action": [
#        "ec2:AssociateAddress",
#        "ec2:DisassociateAddress",
#      ],
#      "Effect": "Allow",
#      "Resource": "*"
#    }
#  ]
# }

pre-start script
  # wait for consul to come available
  until [ -f "/var/consul/run/consul.pid" ]; do
    echo "$(date "+%Y/%m/%d %H:%M:%S") [INFO] waiting on consul"
    /bin/sleep 5
  done

  if [ `echo -n "$(/usr/bin/ec2metadata --public-ip)"` != "unavailable" ]; then
    echo "$(date "+%Y/%m/%d %H:%M:%S") [INFO] Setting shared EIP"
      /usr/local/bin/consulate kv set "haproxy/EIP" $(/usr/bin/ec2metadata --public-ip)
  fi
end script

script
  # since we need a proxy to use the aws cli here
  . /etc/profile.d/proxy
  # a makeshift creds profile that provides the key
  # look at this for an example: https://gist.github.com/jkordish/4392db9993f99f65dc79
  . /etc/profile.d/creds

  # Grab the EIP for the carnifex service from consul.
  export EIP=$(/usr/local/bin/consulate kv get "haproxy/EIP")

  echo "$(date "+%Y/%m/%d %H:%M:%S") [INFO] Starting HA monitor for ${ID}"
  
  # Enter loop...
    while true; do
    # Only evaluate if we currently do not have the EIP assigned.
    if [ `echo -n "$(/usr/bin/ec2metadata --public-ip)"` != "${EIP}" ]; then
      # evaulate if our ping returns nothing. If so reassign!
      export MASTER=`dig +short -p 8600 @localhost haproxy.service.consul | grep -v $(ec2metadata --local-ipv4)`
      if [ -z `echo -n "$(ping -c 3 -W 1 ${MASTER} | awk '/time=/ {count++} END{ print count}')"` ]; then
          echo "$(date "+%Y/%m/%d %H:%M:%S") [INFO] HA heartbeat failed, taking over ${EIP} from ${MASTER}"
          /usr/local/bin/aws ec2 associate-address \
            --allow-reassociation \
            --instance-id ${INSTANCE_ID} \
            --public-ip ${EIP}
        if [ `echo -n "$(/usr/bin/ec2metadata --public-ip)"` != "${EIP}" ]; then
          echo "$(date "+%Y/%m/%d %H:%M:%S") [INFO] successfully reassigned EIP: ${EIP}"
        fi
        sleep 30
      fi
    fi
    sleep 2
  done
end script