networkd: Initial implementation of metrics

Fixes: prometheus-community#101

main.go

@@ -20,6 +20,7 @@ import (
 
 	"github.com/alecthomas/kingpin/v2"
 	"github.com/go-kit/log/level"
+	"github.com/prometheus-community/systemd_exporter/networkd"
 	"github.com/prometheus-community/systemd_exporter/systemd"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
@@ -73,6 +74,17 @@ func main() {
 		os.Exit(1)
 	}
 
+	networkdCollector, err := networkd.NewCollector(logger)
+	if err != nil {
+		level.Error(logger).Log("msg", "Couldn't create networkd collector", "err", err)
+		os.Exit(1)
+	}
+
+	if err := r.Register(networkdCollector); err != nil {
+		level.Error(logger).Log("msg", "Couldn't register networkd collector", "err", err)
+		os.Exit(1)
+	}
+
 	handler := promhttp.HandlerFor(
 		prometheus.Gatherers{exporterMetricsRegistry, r},
 		promhttp.HandlerOpts{

networkd/networkd.go

@@ -0,0 +1,113 @@
+// Copyright 2023 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 networkd
+
+import (
+	"context"
+
+	"github.com/go-kit/log"
+	"github.com/go-kit/log/level"
+	"github.com/godbus/dbus/v5"
+	"github.com/pkg/errors"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const namespace = "networkd"
+
+type Collector struct {
+	ctx                    context.Context
+	logger                 log.Logger
+	leases                 *prometheus.Desc
+	links                  *prometheus.Desc
+	link_carrier_state     *prometheus.Desc
+	link_online_state      *prometheus.Desc
+	link_operational_state *prometheus.Desc
+}
+
+// NewCollector returns a new Collector exporing networkd statistics
+func NewCollector(logger log.Logger) (*Collector, error) {
+	leases := prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "", "dhcpserver_leases_total"),
+		"networkd DHCP server leases",
+		[]string{"iface"}, nil,
+	)
+	links := prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "", "links_total"),
+		"networkd links",
+		nil, nil,
+	)
+
+	ctx := context.TODO()
+	return &Collector{
+		ctx:                    ctx,
+		logger:                 logger,
+		leases:                 leases,
+		links:                  links,
+	}, nil
+}
+
+// Collect gathers metrics from networkd
+func (c *Collector) Collect(ch chan<- prometheus.Metric) {
+	err := c.collect(ch)
+	if err != nil {
+		level.Error(c.logger).Log("msg", "error collecting metrics",
+			"err", err)
+	}
+}
+
+// Describe gathers descriptions of metrics
+func (c *Collector) Describe(desc chan<- *prometheus.Desc) {
+	desc <- c.leases
+	desc <- c.links
+}
+
+func (c *Collector) collect(ch chan<- prometheus.Metric) error {
+	conn, err := dbus.ConnectSystemBus()
+	if err != nil {
+		return errors.Wrapf(err, "could not get DBus connection")
+	}
+	defer conn.Close()
+
+	obj := conn.Object("org.freedesktop.network1", "/org/freedesktop/network1")
+
+	var links [][]interface{}
+
+	err = obj.Call("org.freedesktop.network1.Manager.ListLinks", 0).Store(&links)
+	if err != nil {
+		return level.Warn(c.logger).Log("msg", "Unable to list networkd links", "err", err)
+	}
+
+	// Record number of links
+	ch <- prometheus.MustNewConstMetric(c.links, prometheus.GaugeValue, float64(len(links)))
+
+	//var leases []string
+	for _, v := range links {
+		link_obj_iface := v[1].(string)
+		link_obj_path := v[2].(dbus.ObjectPath)
+
+		link_obj := conn.Object("org.freedesktop.network1", link_obj_path)
+
+		leases_property, err := link_obj.GetProperty("org.freedesktop.network1.DHCPServer.Leases")
+		if err != nil {
+			// No leases found
+			level.Debug(c.logger).Log("msg", "No leases found for interface", "err", err)
+			continue
+		}
+
+		leases_count := len(leases_property.Value().([][]interface{}))
+		ch <- prometheus.MustNewConstMetric(c.leases, prometheus.GaugeValue, float64(leases_count), link_obj_iface)
+	}
+
+	return nil
+}