#!/bin/sh
#
# Revision 1.1  2012/02/26 03:43:27
# Improved labels
#
# Revision 1.0  2012/02/25 21:31:16
# Initial release
#

: <<=cut
=head1 NAME

imap_bandwidth - Munin plugin to measure the current bandwidth of one or more remote IMAP servers.

=head1 APPLICABLE SYSTEMS

Any Linux system with the package "isync" (or "mbsync") installed.

=head1 CONFIGURATION

This configuration section shows a usable example for two imap servers:
   [imap_bandwidth]
   env.imap_servers			internal=imap-internal.example.org external=imap.example.org
   env.cert_file			/etc/munin-imap-cert.pem
   env.username			foo_user
   env.password			secret
   env.transfer_volume_kbyte	100
   env.use_ssl				yes


Both "use_ssl" and "transfer_volume_kbyte" are optional and default to the above
values.
All other parameters are required.

Generate the certificate file by running "mbsync-get-cert imap.example.org".

"imap_servers" is a space-separated list of key=value combinations. "key" is
used as a label in munin graphs. "value" is the full hostname or IP of the IMAP
server. All IMAP servers need to share the same authentication database (i.e.
accept the same username/password).

Reduce the "transfer_volume_kbyte" parameter if you need to minimize traffic.

Maybe you need to specify the "timeout" setting for this plugin if it takes
longer than munin's default timeout.


=head1 INTERPRETATION

The plugin simply shows the average bandwidth during one IMAP upload and one
IMAP download of a file containing random bytes.

You need to be aware that this measurement obviously increases the load on
your IMAP servers for the duration of the measurement.

You also need to be aware of the safety implications imposed by storing
sensitive information (username and password combinations) on your monitoring
server in plaintext.

=head1 VERSION

Version 1.0

=head1 BUGS

None known

Set the environment variable DEBUG=1 if you need to investigate problems.

=head1 AUTHOR

Lars Kruse <devel@sumpfralle.de>

=head1 LICENSE

GPLv3 or higher

=cut


set -eu

#%# family=auto
#%# capabilities=autoconf

TRANSFER_SIZE=${transfer_volume_kbyte:-100}
USE_SSL=${use_ssl:-yes}
IMAP_USERNAME=${username}
IMAP_PASSWORD=${password}
CERT_FILE=${cert_file}

# example value:
#    internal=imap-internal.example.org external=imap.example.org
SERVERS="$imap_servers"


if test -n "${DEBUG:-}"; then
	TRANSFER_SIZE=20
	set -x
fi


. $MUNIN_LIBDIR/plugins/plugin.sh


if [ "$1" = "autoconf" ]; then
	if ( which mbsync >/dev/null 2>&1 ); then
		echo yes
		exit 0
	else
		echo "no (could not run \"mbsync\")"
		exit 0
	fi
fi

if [ "$1" = "config" ]; then
	echo 'graph_title IMAP bandwidth'
	echo 'graph_vlabel to (+) / from (-) server [bit/s]'
	echo 'graph_category mail'
	for item in $SERVERS; do
		key="$(echo "$item" | cut -f 1 -d =)"
		clean_name="$(clean_fieldname "$key")"
		echo "download_${clean_name}.graph no"
		echo "download_${clean_name}.label download"
		echo "upload_${clean_name}.label $key"
		echo "upload_${clean_name}.negative download_${clean_name}"
	 done
	exit 0
fi


create_dummy_file() {
	dd if=/dev/urandom "of=$DUMMY_FILENAME" bs=1K count=${TRANSFER_SIZE} 2>/dev/null
}

is_dummy_file_missing() {
	test ! -e "$DUMMY_FILENAME"
}

remove_mail_files() {
	get_mail_files | while read fname; do rm "$fname"; done
}

get_mail_files() {
	find "$MAILDIR" -type f | grep -v "/\."
}

# run the synchronization
run_sync() {
	if test -n "${DEBUG:-}"; then
		echo yes | mbsync --config "$SYNCRC" sync || true
	else
		echo yes | mbsync --config "$SYNCRC" sync >/dev/null 2>/dev/null || true
	fi
}

# run the synchronization and determine the duration of this operation
speed_sync() {
	start=$(date +%s%N)
	run_sync
	end=$(date +%s%N)
	# did we wrap a minute?
	test "$end" -lt "$start" && end=$((end + 60 * 1000000000))
	delay=$((end - start))
	# use "bit" multiplier
	echo "$((8 * TRANSFER_SIZE * 1024 * 1000000000 / delay))"
}

for item in $SERVERS; do
	key="$(echo "$item" | cut -f 1 -d =)"
	host="$(echo "$item" | cut -f 2- -d =)"
	clean_name="$(clean_fieldname "$key")"
	MAILDIR="$(mktemp -d)"
	# this file needs to include a dot at the beginning - otherwise it gets cleaned up ...
	SYNCRC="$MAILDIR/.mbsyncrc"
	SYNC_STATE_FILE_PREFIX="$MAILDIR/.syncstate-"

	cat - >"$SYNCRC" <<- EOF
	SyncState	$SYNC_STATE_FILE_PREFIX
	Expunge Both

	MaildirStore local
	Path	$MAILDIR
	Inbox	$MAILDIR

	IMAPStore remote
	Host $host
	UseIMAPS $USE_SSL
	User $IMAP_USERNAME
	Pass $IMAP_PASSWORD
	CertificateFile $CERT_FILE

	Channel sync
	Master	:local:
	Slave	:remote:
EOF

	mkdir "$MAILDIR/new" "$MAILDIR/tmp" "$MAILDIR/cur"
	DUMMY_FILENAME="$MAILDIR/new/$(date +%N)"
	# download all existing files
	run_sync
	# remove all local files -> to be purged remotely later
	remove_mail_files
	# create dummy file for upload
	create_dummy_file "$MAILDIR"
	output="upload_${clean_name}.value $(speed_sync)"
	is_dummy_file_missing && echo "$output" || echo >&2 "upload failed"
	# remove local file
	remove_mail_files "$MAILDIR"
	# persuade mbsync that we have never seen the dummy file ...
	rm "$SYNC_STATE_FILE_PREFIX"*
	output="download_${clean_name}.value $(speed_sync)"
	get_mail_files | grep -q . && echo "$output" || echo >&2 "download failed"
	# remove the new file from the imap server
	remove_mail_files
	run_sync
	# clean up
	rm -r "$MAILDIR"
 done