Home Assistant - install imagemagick - user script

For some reason, 'imagemagick' software is not available within 'Home Assistant' container. I need this software for one of Home Assistant components to run.

I have added following script to install this software whenever 'HA' updates gets installed. (for now, I want to install when the container is running). But this script is not working. I used Erik Kristensen's 'check_docker_container.sh' script as a base for this.
 

#!/bin/bash

# Author: Erik Kristensen
# Email: [email protected]
# License: MIT
# Nagios Usage: check_nrpe!check_docker_container!_container_id_
# Usage: ./check_docker_container.sh _container_id_
#
# Depending on your docker configuration, root might be required. If your nrpe user has rights
# to talk to the docker daemon, then root is not required. This is why root privileges are not
# checked.
#
# The script checks if a container is running.
#   OK - running
#   WARNING - restarting
#   CRITICAL - stopped
#   UNKNOWN - does not exist
#


# CONTAINER=$1
CONTAINER="home-assistant"
COUNT=300

if [ "x${CONTAINER}" == "x" ]; then
  echo "UNKNOWN - Container ID or Friendly Name Required"
  exit 3
fi

if [ "x$(which docker)" == "x" ]; then
  echo "UNKNOWN - Missing docker binary"
  exit 3
fi

docker info > /dev/null 2>&1
if [ $? -ne 0 ]; then
  echo "UNKNOWN - Unable to talk to the docker daemon"
  exit 3
fi

RESTARTING=$(docker inspect --format="{{.State.Restarting}}" $CONTAINER)

if [ "$RESTARTING" == "true" ]; then
  echo "WARNING - $CONTAINER state is restarting."
  # Wait five minutes
  # echo COUNT $count
  sleep 300
#  exit 1
else
  now=$(date)
  echo $now
  # Wait five minutes
  # echo COUNT $COUNT
  echo "SLEEP FOR 60 SECS"
  #sleep 60
  echo "Installing ImageMagick"
  echo $CONTAINER
  #RUN apk add ImageMagick
  docker exec -i $CONTAINER apk add ImageMagick
  #apk add -no-cache imagemagick
  echo "Completed installing of imagemagick"
  #echo "WARNING - $CONTAINER state is NOT in restarting mode."
  exit 1
fi

STARTED=$(docker inspect --format="{{.State.StartedAt}}" $CONTAINER)
NETWORK=$(docker inspect --format="{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}" $CONTAINER)

/usr/local/emhttp/webGui/scripts/notify -i normal -s "OK - $CONTAINER is running." -d "StartedAt: $STARTED"

When I tried to run this script manually, I get this error message. What am I missing in the script?
 

Script location: /tmp/user.scripts/tmpScripts/install imagemagick/script
Note that closing this window will abort the execution of this script
Sat Dec 12 15:48:30 CST 2020
SLEEP FOR 60 SECS
Installing ImageMagick
home-assistant
ImageMagick (missing):
ERROR: unsatisfiable constraints:
required by: world[ImageMagick]
Completed installing of imagemagick