feat: add backup collector (pve_not_backed_up_total, pve_not_backed_up_info)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

collector/backup.go

@@ -0,0 +1,69 @@
+package collector
+
+import (
+	"encoding/json"
+	"fmt"
+	"log/slog"
+	"strconv"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+func init() {
+	registerCollector("backup", func(logger *slog.Logger) Collector {
+		return newBackupCollector(logger)
+	})
+}
+
+type backupCollector struct {
+	logger *slog.Logger
+}
+
+func newBackupCollector(logger *slog.Logger) *backupCollector {
+	return &backupCollector{logger: logger}
+}
+
+type backupNotBackedUpResponse struct {
+	Data []backupNotBackedUpEntry `json:"data"`
+}
+
+type backupNotBackedUpEntry struct {
+	VMID int    `json:"vmid"`
+	Name string `json:"name"`
+	Type string `json:"type"`
+}
+
+var (
+	notBackedUpTotalDesc = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "", "not_backed_up_total"),
+		"Whether a guest is not backed up (1 = not backed up).",
+		[]string{"id"},
+		nil,
+	)
+	notBackedUpInfoDesc = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "", "not_backed_up_info"),
+		"Information about a guest that is not backed up.",
+		[]string{"id"},
+		nil,
+	)
+)
+
+func (c *backupCollector) Update(client *Client, ch chan<- prometheus.Metric) error {
+	body, err := client.Get("/cluster/backup-info/not-backed-up")
+	if err != nil {
+		return fmt.Errorf("failed to get /cluster/backup-info/not-backed-up: %w", err)
+	}
+
+	var resp backupNotBackedUpResponse
+	if err := json.Unmarshal(body, &resp); err != nil {
+		return fmt.Errorf("failed to parse backup-info response: %w", err)
+	}
+
+	for _, entry := range resp.Data {
+		id := entry.Type + "/" + strconv.Itoa(entry.VMID)
+		ch <- prometheus.MustNewConstMetric(notBackedUpTotalDesc, prometheus.GaugeValue, 1, id)
+		ch <- prometheus.MustNewConstMetric(notBackedUpInfoDesc, prometheus.GaugeValue, 1, id)
+	}
+
+	return nil
+}

collector/backup_test.go

@@ -0,0 +1,37 @@
+package collector
+
+import (
+	"log/slog"
+	"strings"
+	"testing"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/testutil"
+)
+
+func TestBackupCollector(t *testing.T) {
+	client := newTestClient(t, map[string]string{
+		"/cluster/backup-info/not-backed-up": "backup_not_backed_up.json",
+	})
+
+	collector := newBackupCollector(slog.Default())
+	adapter := &testCollectorAdapter{client: client, collector: collector}
+
+	reg := prometheus.NewRegistry()
+	reg.MustRegister(adapter)
+
+	expected := `
+# HELP pve_not_backed_up_info Information about a guest that is not backed up.
+# TYPE pve_not_backed_up_info gauge
+pve_not_backed_up_info{id="qemu/100"} 1
+# HELP pve_not_backed_up_total Whether a guest is not backed up (1 = not backed up).
+# TYPE pve_not_backed_up_total gauge
+pve_not_backed_up_total{id="qemu/100"} 1
+`
+
+	if err := testutil.GatherAndCompare(reg, strings.NewReader(expected),
+		"pve_not_backed_up_total", "pve_not_backed_up_info",
+	); err != nil {
+		t.Errorf("unexpected metrics: %s", err)
+	}
+}

collector/fixtures/backup_not_backed_up.json

@@ -0,0 +1 @@
+{"data":[{"vmid":100,"name":"pve-backup.freyja.sip.is","type":"qemu"}]}