Install new cloud-init on Debian 10 using packer

debian-10-packer.json

{
    "builders": [
        {
            "type": "openstack",
            "username": "xxx",
            "password": "yyy",
            "identity_endpoint": "https://auth.cloud.ovh.net/v3/",
            "region": "DE1",
            "tenant_id": "zzz",
            "image_name": "debian10-arnaud",
            "ssh_username": "debian",
            "source_image": "6a27a33f-9cb9-4c65-b99c-bb904dfb43aa",
            "flavor": "3be7c73a-735a-4ee1-b8d4-83feb080109d",
            "ssh_ip_version": "4",
            "networks": [
                "ed0ab0c6-93ee-44f8-870b-d103065b1b34"
            ]
        }
    ],
    "provisioners": [
        {
            "script": "setup.sh",
            "type": "shell"
        }
    ]
}

setup.sh

#!/bin/bash

set -e

if [ `id -u` -ne 0 ]; then
    sudo $0
    exit 0
fi

# Setup logging stdout + stderr to logfile
log_file="/var/log/postinstall.log"

function log_handler {
  while IFS='' read -r output; do
    echo $output
    echo "$(date) - $output" >> $log_file
  done
}

function title.print
{
    local string="$1"
    local stringw=$((77 - $(wc -L <<< "$string")))
    echo ""
    echo "┌──────────────────────────────────────────────────────────────────────────────┐"
    echo -n "│ $string"
    for i in $(seq 1 ${stringw}); do echo -n " " ; done
    echo "│"
    echo "└──────────────────────────────────────────────────────────────────────────────┘"
    echo ""
}

exec &> >(log_handler)
export DEBIAN_FRONTEND=noninteractive

title.print "Downloading package"
wget -O cloudinit.deb https://people.debian.org/~noahm/cloud-init/cloud-init_20.1-2~bpo10+1_all.deb

title.print "Installing"
dpkg -i --force-all cloudinit.deb

echo 'done'
echo ''