3g_failover_launcher.sh

#!/bin/bash -x
#
# Local startup customisations. Everything logs to syslog
#

(
exec 1> >(logger -s -t rc-local) 2>&1

# Remove the eth0 default route
/sbin/route del default eth0

# Start up our HTTP server for health checks. We run this in a bash shell
# to ensure automatic restarts if it crashes
(
  while true
  do
    echo "(re)starting the HTTP health check server"
    sudo -u nobody /usr/local/bin/pinghttpserver
    sleep 1
  done
) &

# Setup a wvdial connection with automatic reconnection
# in the background. Only issue is if the PPP process
# terminates itself and leaves the 3G modem in an unclean state,
# we are unable to power cycle it.

(
  i="0"
  while [ $i -lt 5 ]
  do

    # Trigger an update of our dynamic DNS in 60 seconds time
    (
      sleep 60
      export PATH=/usr/local/bin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/sbin

      # Put your dynamic DNS update hook here. I personally use:
      # https://github.com/awslabs/route53-dynamic-dns-with-lambda
    ) &

    # Reconnect wvdial
    echo "(re)starting wvdial for ${i}/10"
    /usr/bin/wvdial

    # wvdial has terminated!
    sleep 30


    i=$[$i+1]
  done

  # We've failed... too many restarts of wvdial
  echo "Too many restarts, power cycling entire device"

  # Power Cycle USB. We do this to fix a bug where the firmware on the 3G modem crashes.
  # Note: This kills *all* USB power, except for the ethernet controller, not just the 3G modem.
  #
  # Note2: This is *very* hardware specific and works on a Raspberry Pi 2. Other models or devices may/will vary.
  /usr/local/bin/hub-ctrl -h 0 -P 2 -p 0
  sleep 5
  /usr/local/bin/hub-ctrl -h 0 -P 2 -p 1

  echo "Rebooting..."
  reboot

) &


)