#!/usr/bin/env bash
#
# JbTecWiz Support Centre -- generated fix script
#
# Fault : /var full -- the journal or logs have consumed the disk
# Fix   : Reclaim the space and cap it permanently
# Source: https://jbtecwiz.com/support/lnx-journal-disk-full
#
# Run as     : Shell as root
# Expect     : 20 minutes
# Risk       : low
# Reversible : yes
#
# WHEN THIS IS THE RIGHT FIX
#   /var is full. Do the capping step as well as the clearing step, or you
#   will be back here in a month.
#
# HOW TO UNDO IT
#   Vacuumed journal entries are gone permanently. The configuration
#   change is reversible by editing journald.conf back.
#
# 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 $n of 7"
  prose "$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 "  /var full -- the journal or logs have consumed the disk"
echo "  Reclaim the space and cap it permanently"
echo
echo "  Risk: low   Reversible   20 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 where the space has gone.' '' cmd 'df -h /var' 'sudo du -xh /var --max-depth=2 2>/dev/null | sort -rh | head -15'; then
  df -h /var
  sudo du -xh /var --max-depth=2 2>/dev/null | sort -rh | head -15
  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 'Check how much the journal is holding.' '' cmd 'journalctl --disk-usage'; then
  journalctl --disk-usage
  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 'Trim it immediately to reclaim space.' '' cmd 'sudo journalctl --vacuum-size=200M'; then
  sudo journalctl --vacuum-size=200M
  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 'Or trim by age instead.' '' cmd 'sudo journalctl --vacuum-time=7d'; then
  sudo journalctl --vacuum-time=7d
  if [ $? -ne 0 ]; then
    failed=$((failed+1))
    echo "  Step 4 failed. The rest of the fix may depend on it." >&2
  fi
fi

if step 5 'Cap it permanently so this cannot recur -- set SystemMaxUse=500M in /etc/systemd/journald.conf.' 'With no cap, journald will use up to 10% of the filesystem. On a large /var that is a lot of logs and on a small one it is enough to fill it.' cmd 'sudo sed -i '\''s/^#\?SystemMaxUse=.*/SystemMaxUse=500M/'\'' /etc/systemd/journald.conf' 'sudo systemctl restart systemd-journald'; then
  sudo sed -i 's/^#\?SystemMaxUse=.*/SystemMaxUse=500M/' /etc/systemd/journald.conf
  sudo systemctl restart systemd-journald
  if [ $? -ne 0 ]; then
    failed=$((failed+1))
    echo "  Step 5 failed. The rest of the fix may depend on it." >&2
  fi
fi

if step 6 'Check logrotate is actually running and not failing silently.' '' cmd 'systemctl status logrotate.timer' 'sudo logrotate -d /etc/logrotate.conf 2>&1 | tail -30'; then
  systemctl status logrotate.timer
  sudo logrotate -d /etc/logrotate.conf 2>&1 | tail -30
  if [ $? -ne 0 ]; then
    failed=$((failed+1))
    echo "  Step 6 failed. The rest of the fix may depend on it." >&2
  fi
fi

if step 7 'Find any single enormous log file that logrotate is not covering.' '' cmd 'sudo find /var/log -type f -size +100M -exec ls -lh {} \;'; then
  sudo find /var/log -type f -size +100M -exec ls -lh {} \;
  if [ $? -ne 0 ]; then
    failed=$((failed+1))
    echo "  Step 7 failed. The rest of the fix may depend on it." >&2
  fi
fi

rule "  Confirm it worked"
prose '/var has free space and the journal is within its cap.'
if [ "$DRYRUN" = "0" ]; then
  df -h /var && journalctl --disk-usage
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-journal-disk-full"
else
  echo "  Finished."
fi
echo
prose 'To undo: Vacuumed journal entries are gone permanently. The configuration change is reversible by editing journald.conf back.'
rule