fix: custom collector for dhcp leases to remove them when they expire

README.md

@@ -59,5 +59,4 @@ scrape_configs:
 | adguard_top_upstreams                             | The number of repsonses for the top upstream servers              |
 | adguard_top_upstreams_avg_response_time_seconds   | The average response time for each of the top upstream servers    |
 | adguard_dhcp_enabled                              | Whether dhcp is enabled                                           |
-| adguard_dhcp_leases                               | The number of dhcp leases                                         |
-| adguard_dhcp_static_leases                        | The number of static dhcp leases                                  |
+| adguard_dhcp_leases                               | The dhcp leases                                         |

internal/adguard/client.go

@@ -8,6 +8,7 @@ import (
 	"io"
 	"net/http"
 	"net/url"
+	"slices"
 
 	"github.com/henrywhitaker3/adguard-exporter/internal/config"
 )
@@ -70,7 +71,24 @@ func (c *Client) GetStatus(ctx context.Context) (*Status, error) {
 func (c *Client) GetDhcp(ctx context.Context) (*DhcpStatus, error) {
 	out := &DhcpStatus{}
 	err := c.do(ctx, http.MethodGet, "/control/dhcp/status", out)
-	return out, err
+	if err != nil {
+		return nil, err
+	}
+
+	for i := range out.DynamicLeases {
+		l := out.DynamicLeases[i]
+		l.Type = "dynamic"
+		out.DynamicLeases[i] = l
+	}
+	for i := range out.StaticLeases {
+		l := out.StaticLeases[i]
+		l.Type = "static"
+		out.StaticLeases[i] = l
+	}
+
+	out.Leases = slices.Concat(out.DynamicLeases, out.StaticLeases)
+
+	return out, nil
 }
 
 func (c *Client) Url() string {

internal/adguard/types.go

@@ -34,10 +34,12 @@ type DhcpLease struct {
 	IP       string `json:"ip"`
 	Hostname string `json:"hostname"`
 	Expires  string `json:"expires,omitempty"`
+	Type     string
 }
 
 type DhcpStatus struct {
-	Enabled      Bool        ` json:"enabled"`
-	Leases       []DhcpLease `json:"leases"`
-	StaticLeases []DhcpLease `json:"static_leases"`
+	Enabled       Bool        ` json:"enabled"`
+	DynamicLeases []DhcpLease `json:"leases"`
+	StaticLeases  []DhcpLease `json:"static_leases"`
+	Leases        []DhcpLease
 }

internal/metrics/metrics.go

@@ -1,6 +1,9 @@
 package metrics
 
 import (
+	"sync"
+
+	"github.com/henrywhitaker3/adguard-exporter/internal/adguard"
 	"github.com/prometheus/client_golang/prometheus"
 )
 
@@ -81,18 +84,53 @@ var (
 		Namespace: "adguard",
 		Help:      "Whether dhcp is enabled",
 	}, []string{"server"})
-	DhcpLeases = prometheus.NewGaugeVec(prometheus.GaugeOpts{
-		Name:      "dhcp_leases",
-		Namespace: "adguard",
-		Help:      "The number of dhcp leases",
-	}, []string{"server"})
-	DhcpStaticLeases = prometheus.NewGaugeVec(prometheus.GaugeOpts{
-		Name:      "dhcp_static_leases",
-		Namespace: "adguard",
-		Help:      "The number of static dhcp leases",
-	}, []string{"server"})
+	DhcpLeasesMetric = prometheus.NewDesc(
+		"adguard_dchp_leases",
+		"The dhcp leases",
+		[]string{"server", "type", "ip", "mac", "hostname"},
+		nil,
+	)
+	DhcpLeases = NewDhcpLeasesServer(DhcpLeasesMetric)
 )
 
+type DhcpLeasesServer struct {
+	mu     *sync.Mutex
+	Desc   *prometheus.Desc
+	leases map[string][]adguard.DhcpLease
+}
+
+func NewDhcpLeasesServer(desc *prometheus.Desc) *DhcpLeasesServer {
+	return &DhcpLeasesServer{
+		mu:     &sync.Mutex{},
+		leases: map[string][]adguard.DhcpLease{},
+		Desc:   desc,
+	}
+}
+
+func (d *DhcpLeasesServer) Record(server string, leases []adguard.DhcpLease) {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+
+	d.leases[server] = leases
+}
+
+func (d *DhcpLeasesServer) Collect(ch chan<- prometheus.Metric) {
+	for server, leases := range d.leases {
+		for _, lease := range leases {
+			ch <- prometheus.MustNewConstMetric(
+				d.Desc,
+				prometheus.CounterValue,
+				1,
+				server, lease.Type, lease.IP, lease.Mac, lease.Hostname,
+			)
+		}
+	}
+}
+
+func (d *DhcpLeasesServer) Describe(ch chan<- *prometheus.Desc) {
+	ch <- d.Desc
+}
+
 func Init() {
 	prometheus.MustRegister(ScrapeErrors)
 
@@ -115,5 +153,4 @@ func Init() {
 	// DHCP
 	prometheus.MustRegister(DhcpEnabled)
 	prometheus.MustRegister(DhcpLeases)
-	prometheus.MustRegister(DhcpStaticLeases)
 }

internal/worker/worker.go

@@ -101,6 +101,5 @@ func collectDhcp(ctx context.Context, client *adguard.Client) {
 		return
 	}
 	metrics.DhcpEnabled.WithLabelValues(client.Url()).Set(float64(dhcp.Enabled.Int()))
-	metrics.DhcpLeases.WithLabelValues(client.Url()).Set(float64(len(dhcp.Leases)))
-	metrics.DhcpStaticLeases.WithLabelValues(client.Url()).Set(float64(len(dhcp.StaticLeases)))
+	metrics.DhcpLeases.Record(client.Url(), dhcp.Leases)
 }