This was my configuration of my image that worked.

vi /etc/init/ttyS0.conf

# ttyS0 - getty
#
# This service maintains a getty on ttyS0 from the point the system is
# started until it is shut down again.

start on stopped rc RUNLEVEL=[2345] and (
            not-container or
            container CONTAINER=lxc or
            container CONTAINER=lxc-libvirt)

stop on runlevel [!2345]

pre-start script
    # getty will not be started if the serial console is not present
    stty -F /dev/ttyS0 -a 2> /dev/null > /dev/null || { stop ; exit 0; }
end script

respawn
script
    exec /sbin/getty -L ttyS0 115200 vt102
end script
# CLOUD_IMG: This file was created/modified by the Cloud Image build process

vi /etc/default/grub

# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
#   info -f grub -n 'Simple configuration'

GRUB_DEFAULT=0
GRUB_HIDDEN_TIMEOUT=0
GRUB_HIDDEN_TIMEOUT_QUIET=true
GRUB_TIMEOUT=0
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="console=tty1 console=ttyS0"
GRUB_CMDLINE_LINUX=""

update-grub