DHCP Lease Collector (#50)

* DHCP Leases Collector

Add Information about DHCP Leases:
* Active MAC Address
* Active Address
* Hostname
* Status
* Expire time

* Modified resource collector

Add Boardname and RouterOS version metrics

collector/dhcp_lease_collector.go

@@ -0,0 +1,69 @@
+package collector
+
+import (
+	"strings"
+	"github.com/prometheus/client_golang/prometheus"
+	log "github.com/sirupsen/logrus"
+	"gopkg.in/routeros.v2/proto"
+)
+
+type dhcpLeaseCollector struct {
+	props        []string
+	descriptions *prometheus.Desc
+}
+
+func (c *dhcpLeaseCollector) init() {
+	c.props = []string{"active-mac-address", "status", "expires-after", "active-address", "host-name"}
+
+	labelNames := []string{"name", "address", "activemacaddress", "status", "expiresafter", "activeaddress", "hostname"}
+	c.descriptions = description("dhcp", "leases_metrics", "number of metrics", labelNames)
+
+}
+
+func newDHCPLCollector() routerOSCollector {
+	c := &dhcpLeaseCollector{}
+	c.init()
+	return c
+}
+
+func (c *dhcpLeaseCollector) describe(ch chan<- *prometheus.Desc) {
+	ch <- c.descriptions
+}
+
+func (c *dhcpLeaseCollector) collect(ctx *collectorContext) error {
+	stats, err := c.fetch(ctx)
+	if err != nil {
+		return err
+	}
+
+	for _, re := range stats {
+		c.collectMetric(ctx, re)
+	}
+
+	return nil
+}
+
+func (c *dhcpLeaseCollector) fetch(ctx *collectorContext) ([]*proto.Sentence, error) {
+	reply, err := ctx.client.Run("/ip/dhcp-server/lease/print", "=.proplist="+strings.Join(c.props, ","))
+	if err != nil {
+		log.WithFields(log.Fields{
+			"device": ctx.device.Name,
+			"error":  err,
+		}).Error("error fetching DHCP leases metrics")
+		return nil, err
+	}
+
+	return reply.Re, nil
+}
+
+func (c *dhcpLeaseCollector) collectMetric(ctx *collectorContext, re *proto.Sentence) {
+	v := 1.0
+
+	activemacaddress := re.Map["active-mac-address"]
+	status := re.Map["status"]
+	expiresafter := re.Map["expires-after"]
+	activeaddress := re.Map["active-address"]
+	hostname := re.Map["host-name"]
+
+	ctx.ch <- prometheus.MustNewConstMetric(c.descriptions, prometheus.CounterValue, v, ctx.device.Name, ctx.device.Address, activemacaddress, status, expiresafter, activeaddress, hostname)
+}