From 87ccaa39c9e076a6d7e257124ffe03d544681206 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?R=C3=A9mi=20Audebert?= <halfr@lse.epita.fr>
Date: Sun, 6 Dec 2015 22:33:47 +0100
Subject: [PATCH] collector: add systemd

---
 README.md                       |  1 +
 collector/systemd_linux.go      | 81 +++++++++++++++++++++++++++++++++
 collector/systemd_linux_test.go | 74 ++++++++++++++++++++++++++++++
 3 files changed, 156 insertions(+)
 create mode 100644 collector/systemd_linux.go
 create mode 100644 collector/systemd_linux_test.go

diff --git a/README.md b/README.md
index ba9e63e9..99764fb8 100644
--- a/README.md
+++ b/README.md
@@ -50,6 +50,7 @@ megacli | Exposes RAID statistics from MegaCLI.
 ntp | Exposes time drift from an NTP server.
 runit | Exposes service status from [runit](http://smarden.org/runit/).
 supervisord | Exposes service status from [supervisord](http://supervisord.org/).
+systemd | Exposes service and system status from [systemd](http://www.freedesktop.org/wiki/Software/systemd/).
 tcpstat | Exposes TCP connection status information from `/proc/net/tcp` and `/proc/net/tcp6`. (Warning: the current version has potential performance issues in high load situations.)
 
 ## Textfile Collector
diff --git a/collector/systemd_linux.go b/collector/systemd_linux.go
new file mode 100644
index 00000000..10f239a0
--- /dev/null
+++ b/collector/systemd_linux.go
@@ -0,0 +1,81 @@
+// Copyright 2015 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build !nosystemd
+
+package collector
+
+import (
+	"fmt"
+
+	"github.com/coreos/go-systemd/dbus"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+type systemdCollector struct {
+	unitDesc *prometheus.Desc
+}
+
+var unitStatesName = []string{"active", "activating", "deactivating", "inactive", "failed"}
+
+func init() {
+	Factories["systemd"] = NewSystemdCollector
+}
+
+// Takes a prometheus registry and returns a new Collector exposing
+// systemd statistics.
+func NewSystemdCollector() (Collector, error) {
+	unitDesc := prometheus.NewDesc(
+		prometheus.BuildFQName(Namespace, "systemd", "unit_state"),
+		"Systemd unit", []string{"name", "state"}, nil,
+	)
+
+	return &systemdCollector{
+		unitDesc: unitDesc,
+	}, nil
+}
+
+func (c *systemdCollector) Update(ch chan<- prometheus.Metric) (err error) {
+	units, err := c.listUnits()
+	if err != nil {
+		return fmt.Errorf("couldn't get units states: %s", err)
+	}
+
+	c.collectMetrics(ch, units)
+
+	return nil
+}
+
+func (c *systemdCollector) collectMetrics(ch chan<- prometheus.Metric, units []dbus.UnitStatus) {
+	for _, unit := range units {
+		for _, stateName := range unitStatesName {
+			isActive := 0.0
+			if stateName == unit.ActiveState {
+				isActive = 1.0
+			}
+			ch <- prometheus.MustNewConstMetric(
+				c.unitDesc, prometheus.GaugeValue, isActive,
+				unit.Name, stateName)
+		}
+	}
+}
+
+func (c *systemdCollector) listUnits() ([]dbus.UnitStatus, error) {
+	conn, err := dbus.New()
+	if err != nil {
+		return nil, fmt.Errorf("couldn't get dbus connection: %s", err)
+	}
+	units, err := conn.ListUnits()
+	conn.Close()
+	return units, err
+}
diff --git a/collector/systemd_linux_test.go b/collector/systemd_linux_test.go
new file mode 100644
index 00000000..f5390140
--- /dev/null
+++ b/collector/systemd_linux_test.go
@@ -0,0 +1,74 @@
+// Copyright 2015 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package collector
+
+import (
+	"testing"
+
+	"github.com/coreos/go-systemd/dbus"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+// Creates mock UnitLists
+func getUnitListFixtures() [][]dbus.UnitStatus {
+	fixture1 := []dbus.UnitStatus{
+		dbus.UnitStatus{
+			Name:        "foo",
+			Description: "foo desc",
+			LoadState:   "loaded",
+			ActiveState: "active",
+			SubState:    "running",
+			Followed:    "",
+			Path:        "/org/freedesktop/systemd1/unit/foo",
+			JobId:       0,
+			JobType:     "",
+			JobPath:     "/",
+		},
+		dbus.UnitStatus{
+			Name:        "bar",
+			Description: "bar desc",
+			LoadState:   "not-found",
+			ActiveState: "inactive",
+			SubState:    "dead",
+			Followed:    "",
+			Path:        "/org/freedesktop/systemd1/unit/bar",
+			JobId:       0,
+			JobType:     "",
+			JobPath:     "/",
+		},
+	}
+
+	fixture2 := []dbus.UnitStatus{}
+
+	return [][]dbus.UnitStatus{fixture1, fixture2}
+}
+
+func TestSystemdCollectorDoesntCrash(t *testing.T) {
+	c, err := NewSystemdCollector()
+	if err != nil {
+		t.Fatal(err)
+	}
+	sink := make(chan prometheus.Metric)
+	go func() {
+		for {
+			<-sink
+		}
+	}()
+
+	fixtures := getUnitListFixtures()
+	collector := (c).(*systemdCollector)
+	for _, units := range fixtures {
+		collector.collectMetrics(sink, units)
+	}
+}