leapp rhel 7 to rhel 8

upgrade-to-rhel8

#!/bin/bash
if ! command -v subscription-manager > /dev/null; then echo "Cannot find subscription-manager"; exit 1; fi
if ! sudo subscription-manager status | grep -q 'Current'; then echo "Current subscription is not current!"; exit 1; fi
if grep -qvF 7.6 <(paste -s </etc/os-release); then if sudo subscription-manager release | grep -Eqv 'Release: 7(\.6|Server)'; then echo "Subscription is not to 7.6 or 7Server. Updating."; sudo subscription-manager release --set=7Server; fi; fi
sudo subscription-manager repos --disable="*" --enable=rhel-7-server-rpms --enable=rhel-7-server-supplementary-rpms --enable=rhel-7-server-extras-rpms
for repo in $(sudo repoquery --all --qf "%-20{ui_from_repo}" | sed -e 's#^@##g' | sort -u); do
  if grep -Fqv "${repo}" <(paste -s </etc/yum.repos.d/redhat.repo); then
    nonrhelrepos+=("${repo}")
  fi
done

if [ "${#nonrhelrepos}" -gt 0 ]; then
  echo "Found non-redhat repositories installed. Checking for installed packages from those repos."
  for repo in "${nonrhelrepos[@]}"; do
    for package in $(sudo repoquery --all --installed --qf "%-20{ui_from_repo} %-30{name}" | grep -E "^@${repo}" | awk '{print$2}'); do
      repopackages+=("${package}")
    done
    if [ -n "${repopackages[*]}" ]; then
      echo "From ${repo}:"
      printf '\t%s\n' "${repopackages[@]}"
      for package in "${repopackages[@]}"; do packages+=("${package}"); done
      unset repopackages
    fi
  done
fi
if [ "${#packages}" -gt 0 ]; then
  if [ "${1}" != "-f" ]; then
    read -p "Uninstall all non-redhat packages to ensure a smooth upgrade? [N/y]" -N 1 -r forceuninstall
  fi
  if [ "${1}" = "-f" ] || [ "${forceuninstall}" = y ] || [ "${forceuninstall}" = Y ]; then
    sudo yum remove "${packages[*]}" -y
  fi
fi
echo "Running distro-sync to make sure we're at least a little bit up to date"
sudo yum distro-sync -y
echo "Installing leapp"
sudo yum install leapp -y
echo "Downloading rhel8 upgrade files"
curl -SsL https://access.redhat.com/sites/default/files/attachments/leapp-data3.tar.gz | sudo tar xzC /etc/leapp/files
echo "Running leapp upgrade"
sudo leapp upgrade

It helps for reach final state of prerequisites for RHEL8 upgrade starting with Leapp.