#!/bin/sh
: << =cut

=head1 NAME

systemd_mem - Plugin to graph the memory usage of multiple systemd services as reported by systemctl

=head1 CONFIGURATION

The environment variable "services" is used to provide a space separated list of services to graph.

Example:
   [systemd_mem]
   env.services apache2 tomcat9 mysql

env.services defaults to "munin-node".

As an alternative you can use all_services to display memory for all running systemd services
   [systemd_mem]
   env.all_services true

all_services shows memory for all running units of type service.

=head1 VERSION

1.1

=head1 AUTHORS

Paul Alexandrow <paul@alexandrow.org>
Andreas Perhab <a.perhab@wtioit.at>

=head1 LICENSE

Copyright 2021 Paul Alexandrow, paul@alexandrow.org

Permission is hereby granted, free of charge, to any person obtaining a copy of this software
and associated documentation files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or
substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

=head1 MAGIC MARKERS

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

=cut

. "$MUNIN_LIBDIR/plugins/plugin.sh"

# at least on debian stretch services report this as unlimited / unknown value (2^64)
# see https://lists.freedesktop.org/archives/systemd-devel/2018-July/041092.html
SYSTEMD_UNLIMITED="18446744073709551615"

all_services=${all_services:-}
services=${services:-"munin-node"}

for_services() {
    if [ "$all_services" != "" ]; then
        systemctl --type=service --state=running --no-pager --no-legend --output=short-precise \
          | awk '{sub(".service$", "", $1); print $1}'
    else
        echo "$services"
    fi
}

output_config() {
    echo "graph_title Systemd Service Memory Usage"
    echo "graph_info Memory usage for selected services as reported by systemctl"
    echo "graph_vlabel bytes"
    echo "graph_args --base 1024 --lower-limit 0"
    echo "graph_category memory"
    for service in $(for_services); do
        clean_name="$(clean_fieldname "$service")"
        description=$(systemctl show "$service" --property=Description | cut -d '=' -f 2-)
        warning=$(systemctl show "$service" --property=MemoryHigh | cut -d '=' -f 2)
        critical=$(systemctl show "$service" --property=MemoryMax | cut -d '=' -f 2)
        if [ "$critical" = "infinity" ] || [ "$critical" = "$SYSTEMD_UNLIMITED" ] ; then
            critical=$(systemctl show "$service" --property=MemoryLimit | cut -d '=' -f 2)
        fi
        printf "%s.label %s\n" "$clean_name" "$description"
        printf "%s.info memory usage\n" "$clean_name"
        if [ "$warning" != "infinity" ] && [ "$warning" != "$SYSTEMD_UNLIMITED" ] ; then
          printf "%s.warning %s\n" "$clean_name" "$warning"
        fi
        if [ "$critical" != "infinity" ] && [ "$critical" != "$SYSTEMD_UNLIMITED" ] ; then
          printf "%s.critical %s\n" "$clean_name" "$critical"
        fi
    done
}

output_values() {
    for service in $(for_services); do
        clean_name="$(clean_fieldname "$service")"
        usage=$(systemctl show "$service" --property=MemoryCurrent | cut -d '=' -f 2)
        if [ "$usage" = "[not set]" ] || [ "$usage" = "$SYSTEMD_UNLIMITED" ]; then
            usage="U"
        fi
        printf  "%s.value %s\n" "$clean_name" "$usage"
    done
}

output_usage() {
    printf >&2 "%s - munin plugin to graph memory usage for systemd services\n" "${0##*/}"
    printf >&2 "Usage: %s [config]\n" "${0##*/}"
}

output_autoconf() {
    if command -v systemctl >/dev/null 2>&1; then
       echo "yes"
    else
        echo "no (systemctl not found)";
    fi
}

case $# in
    0)
        output_values
        ;;
    1)
        case $1 in
            autoconf)
                output_autoconf
                ;;
            config)
                output_config
                ;;
            fetch)
                output_values
                ;;
            *)
                output_usage
                exit 1
                ;;
        esac
        ;;
    *)
        output_usage
        exit 1
        ;;
esac