Add type to backup files using targz.

type/__dirbackup/man.rst

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+cdist-type__dirbackup(7)
+========================
+
+NAME
+----
+cdist-type__dirbackup - Periodically tar a directory somewhere else.
+
+DESCRIPTION
+-----------
+
+This type writes a script to tar a directory somewhere else accessible through
+a filesystem, keeping only copies older than the requested days. The source
+directory (or file, the type doesn't actually make a difference) to be targz'd
+is expected as "$__object_id".
+
+REQUIRED PARAMETERS
+-------------------
+
+destination
+  The directory in which the backups are to be copied. Expects an absolute
+  path. It will be created if it does not exist, but beware as it will then
+  have cdist's default restrictive permissions.
+
+frequency
+  The directory in `/etc/periodic` to link the backup script to. Usual existing
+  values are `15mn`, `hourly`, `daily`, `weekly`, `monthly`. Values here depend
+  on your distribution an cron setup; this type currently only supports Alpine
+  Linux, who's default values are the above mentioned.
+
+keep
+  The amount of days to keep data. A natural integer is expected, it is
+  directly passed on to the `-mtime` argument of `find(1)`.
+
+AUTHORS
+-------
+Joachim Desroches <joachim.desroches@epfl.ch>
+
+COPYING
+-------
+Copyright \(C) 2020 Joachim Desroches. You can redistribute it
+and/or modify it under the terms of the GNU General Public License as
+published by the Free Software Foundation, either version 3 of the
+License, or (at your option) any later version.

type/__dirbackup/manifest

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+#!/bin/sh
+
+os="$(cat "${__global:?}"/explorer/os)"
+
+case "$os" in
+	alpine)
+		:
+	;;
+	*)
+		echo "This type has no implementation for $os. Aborting." >&2
+		exit 1
+	;;
+esac
+
+scriptname="dirbackup-$(dd if=/dev/random bs=1 count=16 | tr -dC '[:alnum:]')"
+
+destination="$(cat "${__object:?}/parameter/destination")"
+frequency="$(cat "${__object:?}/parameter/frequency")"
+keep="$(cat "${__object:?}/parameter/keep")"
+src="/${__object_id:?}"
+
+srcstrip="$(basename "$src")"
+
+__directory "$destination" --parents
+__file "/etc/periodic/$frequency/$scriptname" \
+	--mode 0755 \
+	--source - <<- EOF
+		#!/bin/sh
+		tar -czpf "$destination/$srcstrip-\$(date -I).tar.gz" -C '$(dirname "$src")' '$srcstrip'
+		find '$destination' -mtime '$keep' -exec rm {} \;
+	EOF

type/__dirbackup/parameter/required

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+frequency
+destination
+keep