feat: add subscription collector (info, status, next_due_timestamp)

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

collector/fixtures/node_subscription.json

@@ -0,0 +1 @@
+{"data":{"status":"active","level":"b","productname":"Proxmox VE Basic Subscription","nextduedate":"2027-02-03","regdate":"2025-02-03","key":"pve2b-test","sockets":2,"checktime":1773896474}}

collector/subscription.go

@@ -0,0 +1,128 @@
+package collector
+
+import (
+	"encoding/json"
+	"fmt"
+	"log/slog"
+	"sync"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+func init() {
+	registerCollector("subscription", func(logger *slog.Logger) Collector {
+		return newSubscriptionCollector(logger)
+	})
+}
+
+type subscriptionCollector struct {
+	logger *slog.Logger
+	mu     sync.Mutex
+	nodes  []string
+}
+
+func newSubscriptionCollector(logger *slog.Logger) *subscriptionCollector {
+	return &subscriptionCollector{logger: logger}
+}
+
+func (c *subscriptionCollector) SetNodes(nodes []string) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.nodes = nodes
+}
+
+type subscriptionResponse struct {
+	Data subscriptionData `json:"data"`
+}
+
+type subscriptionData struct {
+	Status      string `json:"status"`
+	Level       string `json:"level"`
+	NextDueDate string `json:"nextduedate"`
+}
+
+var (
+	subscriptionInfoDesc = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "subscription", "info"),
+		"Subscription information for a node.",
+		[]string{"id", "level"},
+		nil,
+	)
+	subscriptionStatusDesc = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "subscription", "status"),
+		"Subscription status for a node.",
+		[]string{"id", "status"},
+		nil,
+	)
+	subscriptionNextDueDesc = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "subscription", "next_due_timestamp_seconds"),
+		"Next due date of the subscription as a Unix timestamp.",
+		[]string{"id"},
+		nil,
+	)
+)
+
+func (c *subscriptionCollector) Update(client *Client, ch chan<- prometheus.Metric) error {
+	c.mu.Lock()
+	nodes := make([]string, len(c.nodes))
+	copy(nodes, c.nodes)
+	c.mu.Unlock()
+
+	var (
+		wg   sync.WaitGroup
+		errs []error
+		emu  sync.Mutex
+	)
+
+	sem := make(chan struct{}, client.MaxConcurrent())
+
+	for _, node := range nodes {
+		wg.Add(1)
+		go func(node string) {
+			defer wg.Done()
+			sem <- struct{}{}
+			defer func() { <-sem }()
+
+			if err := c.collectNode(client, ch, node); err != nil {
+				emu.Lock()
+				errs = append(errs, err)
+				emu.Unlock()
+			}
+		}(node)
+	}
+	wg.Wait()
+
+	if len(errs) > 0 {
+		return fmt.Errorf("subscription collection errors: %v", errs)
+	}
+	return nil
+}
+
+func (c *subscriptionCollector) collectNode(client *Client, ch chan<- prometheus.Metric, node string) error {
+	body, err := client.Get(fmt.Sprintf("/nodes/%s/subscription", node))
+	if err != nil {
+		return fmt.Errorf("failed to get subscription for node %s: %w", node, err)
+	}
+
+	var resp subscriptionResponse
+	if err := json.Unmarshal(body, &resp); err != nil {
+		return fmt.Errorf("failed to parse subscription response for node %s: %w", node, err)
+	}
+
+	id := "node/" + node
+
+	ch <- prometheus.MustNewConstMetric(subscriptionInfoDesc, prometheus.GaugeValue, 1, id, resp.Data.Level)
+	ch <- prometheus.MustNewConstMetric(subscriptionStatusDesc, prometheus.GaugeValue, 1, id, resp.Data.Status)
+
+	if resp.Data.NextDueDate != "" {
+		t, err := time.Parse("2006-01-02", resp.Data.NextDueDate)
+		if err != nil {
+			c.logger.Warn("failed to parse nextduedate", "node", node, "err", err)
+		} else {
+			ch <- prometheus.MustNewConstMetric(subscriptionNextDueDesc, prometheus.GaugeValue, float64(t.Unix()), id)
+		}
+	}
+
+	return nil
+}

collector/subscription_test.go

@@ -0,0 +1,41 @@
+package collector
+
+import (
+	"log/slog"
+	"strings"
+	"testing"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/testutil"
+)
+
+func TestSubscriptionCollector(t *testing.T) {
+	client := newTestClient(t, map[string]string{
+		"/nodes/node01/subscription": "node_subscription.json",
+	})
+
+	collector := newSubscriptionCollector(slog.Default())
+	collector.SetNodes([]string{"node01"})
+	adapter := &testCollectorAdapter{client: client, collector: collector}
+
+	reg := prometheus.NewRegistry()
+	reg.MustRegister(adapter)
+
+	expected := `
+# HELP pve_subscription_info Subscription information for a node.
+# TYPE pve_subscription_info gauge
+pve_subscription_info{id="node/node01",level="b"} 1
+# HELP pve_subscription_next_due_timestamp_seconds Next due date of the subscription as a Unix timestamp.
+# TYPE pve_subscription_next_due_timestamp_seconds gauge
+pve_subscription_next_due_timestamp_seconds{id="node/node01"} 1.8016128e+09
+# HELP pve_subscription_status Subscription status for a node.
+# TYPE pve_subscription_status gauge
+pve_subscription_status{id="node/node01",status="active"} 1
+`
+
+	if err := testutil.GatherAndCompare(reg, strings.NewReader(expected),
+		"pve_subscription_info", "pve_subscription_status", "pve_subscription_next_due_timestamp_seconds",
+	); err != nil {
+		t.Errorf("unexpected metrics: %s", err)
+	}
+}