#!/bin/bash -u

: << =cut

=head1 NAME

fresh-backups - Plugin to monitor the freshness of backup files

=head1 APPLICABLE SYSTEMS

Any system with some automated backup creating or updating archive files.

This works well with backup-manager.

=head1 CONFIGURATION

The following example checks all tar.bz2 files in /path/to/your/backups/, and
counts all those that are less than 2 days old, and there should be 4 separate
daily archives.

	[fresh-backups]
	user root
	env.backup_dir /path/to/your/backups/
	env.lifetime 2
	env.archive_pattern *.tar.bz2
	env.backup_number 4

This will also set the warning and critical values for this plugin to 2*4 and
4, respectively, meaning that if the number of fresh files goes below those
limits, the relevant notifications will be triggered.

An example configuration snippet for backup-manager [0] follows.

	export BM_REPOSITORY_ROOT="/path/to/your/backups"
	export BM_TARBALL_FILETYPE="tar.bz2"
	export BM_TARBALL_DIRECTORIES="/etc /home /srv /data"

[0] https://github.com/sukria/Backup-Manager

=head1 AUTHOR

Copyright (C) 2016,2019 Olivier Mehani <shtrom+munin@ssji.net>

=head1 LICENSE

SPDX-License-Identifier: GPL-3.0-or-later

=head1 MAGIC MARKERS

 #%# family=manual

=cut

# Bash is needed for this array to work
COLOUR=(00FF00 24DA00 48B600 6D9100 916D00 B64800 DA2400 FF0000)  # green to red

if [ "${MUNIN_DEBUG:-0}" = 1 ]; then
    set -x
fi
# Configuration directives, edit before first use.
BACKUP_DIR=${backup_dir:-/data/backup}
ARCHIVE_PATTERN="${archive_pattern:-*.tar.bz2}"
# How old backups should be considered as non-young anymore in [days].
LIFETIME=${lifetime:-2}
# Critical states will be issued when the number of fresh backups archives is below `backup_number`,
# and warnings below `backup_number*lifetime - 1`
CRIT=${backup_number:-1}
# We should have at least LIFETIME-1 complete backups when the new one is in progress
WARN=$((CRIT*(LIFETIME-1)))

# The situation is critical if there are no young files, the backup is down.
case ${1:-} in
   config)
        cat << EOF
graph_title Fresh backups
graph_info Number of fresh (<=${LIFETIME}d) backups archives in ${BACKUP_DIR}
graph_args -l 0
graph_category backup
EOF
for AGE in $(seq "${LIFETIME}" -1 0); do
	if [ "${AGE}" = 0 ]; then
		echo "age${AGE}.label today"
	else
		echo "age${AGE}.label older than $((AGE*24))h"
	fi
	cat << EOF
age${AGE}.draw AREASTACK
age${AGE}.colour ${COLOUR[$AGE]}
age${AGE}.warning 
age${AGE}.critical 
EOF
done
cat << EOF
freshcount.label ${ARCHIVE_PATTERN} files fresher than ${LIFETIME}d
freshcount.critical ${CRIT}:
freshcount.warning ${WARN}:
freshcount.colour 0080FF
EOF
        exit 0;;
esac

for AGE in $(seq "${LIFETIME}" -1 0); do
	FILES=$(find "${BACKUP_DIR}" \
		-name "${ARCHIVE_PATTERN}" \
		-mmin "-$(((AGE+1)*60*24))" \
		-not -mmin "-$(((AGE)*60*24))" \
		)
	COUNT="$(echo "${FILES}" \
		 | wc -l)"
	echo "age${AGE}.value $((COUNT))"
	# shellcheck disable=SC2086
	echo "age${AGE}.extinfo $(echo ${FILES}  | sort | sed "s^${BACKUP_DIR}^^g")"
done

COUNT=$(find "${BACKUP_DIR}" \
	-name "${ARCHIVE_PATTERN}" \
	-mmin "-$(((LIFETIME+1)*60*24))" \
	| wc -l)
# The last count is also our total count
echo "freshcount.value ${COUNT}"
echo "freshcount.extinfo $(du -sh "${BACKUP_DIR}")"