#!/usr/bin/env bash
#
# JbTecWiz Support Centre -- generated fix script
#
# Fault : "Failed to synchronize cache for repo" / "Cannot prepare internal mirrorlist"
# Fix   : Repoint a CentOS 7 or 8 system at the vault
# Source: https://jbtecwiz.com/support/lnx-dnf-cache
#
# Run as     : Shell as root
# Expect     : 30 minutes
# Risk       : medium
# Reversible : yes
#
# WHEN THIS IS THE RIGHT FIX
#   CentOS 7 or CentOS 8. The mirrorlist service no longer answers for
#   these, so this is not a network fault -- the mirrors are gone.
#
# HOW TO UNDO IT
#   sudo rm -rf /etc/yum.repos.d && sudo mv /etc/yum.repos.d.bak
#   /etc/yum.repos.d
#
# Walks the fix one step at a time and asks before each. Steps with no
# command are yours to do -- it prints those and waits. DRYRUN=1 prints
# without executing; UNATTENDED=1 does not ask.
#
# --------------------------------------------------------------------
# NO WARRANTY - USE AT YOUR OWN RISK
#
# This script is provided by JbTecWiz as-is and with no warranty of any
# kind, express or implied. You run it entirely at your own risk.
#
# JbTecWiz accepts no liability for any loss or damage arising from its
# use, including but not limited to data loss, downtime, or configuration
# changes that turn out to be wrong for your system.
#
# You are responsible for reading this script before running it, for
# satisfying yourself that it suits the machine in front of you, and for
# having a working backup first. Some steps cannot be undone.
# --------------------------------------------------------------------

set -uo pipefail
DRYRUN="${DRYRUN:-0}"
UNATTENDED="${UNATTENDED:-0}"
failed=0

if [ "$(id -u)" -ne 0 ]; then
  echo "  This fix is documented as needing root. Re-run with sudo." >&2
  exit 3
fi

rule() { printf "\n%s\n" "$(printf '-%.0s' $(seq 1 70))"; if [ $# -gt 0 ]; then echo "$1"; fi; }
prose() { echo "$1" | fold -s -w 74 | sed "s/^/  /"; }

# Returns 0 when the caller should run the command, 1 when it should not.
# A manual step always returns 1 -- there is nothing for the caller to run.
step() {  # step <n> <do> <why> <manual|cmd> [command lines...]
  local n="$1" dotext="$2" why="$3" mode="$4"; shift 4
  rule "  Step $n of 5"
  prose "$dotext"
  if [ -n "$why" ]; then echo; prose "$why"; fi
  if [ "$mode" = "manual" ]; then
    echo; echo "  -> Do this yourself, then press Enter to carry on."
    if [ "$UNATTENDED" = "0" ] && [ "$DRYRUN" = "0" ]; then read -r _; fi
    return 1
  fi
  echo; printf "    %s\n" "$@"; echo
  if [ "$DRYRUN" = "1" ]; then echo "  (dry run -- not executed)"; return 1; fi
  if [ "$UNATTENDED" = "0" ]; then
    read -r -p "  Run this step? [Y]es / [S]kip / [Q]uit " a
    case "$a" in
      [Qq]*) echo "  Stopped at your request."; exit 0 ;;
      [Ss]*) echo "  Skipped."; return 1 ;;
    esac
  fi
  return 0
}

rule
echo "  "Failed to synchronize cache for repo" / "Cannot prepare internal mirrorlist""
echo "  Repoint a CentOS 7 or 8 system at the vault"
echo
echo "  Risk: medium   Reversible   30 minutes"
echo
prose 'No warranty. Use at your own risk - JbTecWiz accepts no liability. Read it before you run it, and have a backup.'
rule
echo
if [ "$UNATTENDED" = "0" ] && [ "$DRYRUN" = "0" ]; then
  read -r -p "  Ready? [y/N] " go
  case "$go" in [Yy]*) ;; *) echo "  Nothing was changed."; exit 0;; esac
fi

if step 1 'Confirm the version.' '' cmd 'cat /etc/centos-release'; then
  cat /etc/centos-release
  if [ $? -ne 0 ]; then
    failed=$((failed+1))
    echo "  Step 1 failed. The rest of the fix may depend on it." >&2
  fi
fi

if step 2 'Back up the repo files before editing them.' '' cmd 'sudo cp -a /etc/yum.repos.d /etc/yum.repos.d.bak'; then
  sudo cp -a /etc/yum.repos.d /etc/yum.repos.d.bak
  if [ $? -ne 0 ]; then
    failed=$((failed+1))
    echo "  Step 2 failed. The rest of the fix may depend on it." >&2
  fi
fi

if step 3 'Comment out the mirrorlist lines and point baseurl at vault.centos.org.' 'The vault holds the final released packages. It receives no security updates -- this restores the ability to install, not the ability to patch.' cmd 'sudo sed -i -e '\''s/^mirrorlist=/#mirrorlist=/'\'' -e '\''s|^#\?baseurl=http://mirror.centos.org|baseurl=https://vault.centos.org|'\'' /etc/yum.repos.d/CentOS-*.repo'; then
  sudo sed -i -e 's/^mirrorlist=/#mirrorlist=/' -e 's|^#\?baseurl=http://mirror.centos.org|baseurl=https://vault.centos.org|' /etc/yum.repos.d/CentOS-*.repo
  if [ $? -ne 0 ]; then
    failed=$((failed+1))
    echo "  Step 3 failed. The rest of the fix may depend on it." >&2
  fi
fi

if step 4 'Rebuild the cache.' '' cmd 'sudo yum clean all && sudo yum makecache'; then
  sudo yum clean all && sudo yum makecache
  if [ $? -ne 0 ]; then
    failed=$((failed+1))
    echo "  Step 4 failed. The rest of the fix may depend on it." >&2
  fi
fi

step 5 'Understand this is a holding action. The system is out of support and receives no security fixes; plan a migration to Rocky, Alma or RHEL.' 'Leaving an EOL distribution on the network indefinitely is a far bigger problem than the one being fixed here.' manual || true

rule "  Confirm it worked"
prose 'yum can list and install packages.'
if [ "$DRYRUN" = "0" ]; then
  sudo yum repolist
fi

rule
if [ "$failed" -gt 0 ]; then
  echo "  Finished with $failed failed step(s)."
  echo "  Read the full write-up at https://jbtecwiz.com/support/lnx-dnf-cache"
else
  echo "  Finished."
fi
echo
prose 'To undo: sudo rm -rf /etc/yum.repos.d && sudo mv /etc/yum.repos.d.bak /etc/yum.repos.d'
rule