feat: add corosync collector (quorate, nodes_total, expected_votes, node_online)

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

collector/corosync.go

@@ -0,0 +1,118 @@
+package collector
+
+import (
+	"encoding/json"
+	"fmt"
+	"log/slog"
+	"strconv"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+func init() {
+	registerCollector("corosync", func(logger *slog.Logger) Collector {
+		return newCorosyncCollector(logger)
+	})
+}
+
+type corosyncCollector struct {
+	logger *slog.Logger
+}
+
+func newCorosyncCollector(logger *slog.Logger) *corosyncCollector {
+	return &corosyncCollector{logger: logger}
+}
+
+type clusterConfigNodesResponse struct {
+	Data []clusterConfigNodeEntry `json:"data"`
+}
+
+type clusterConfigNodeEntry struct {
+	Node        string `json:"node"`
+	NodeID      string `json:"nodeid"`
+	QuorumVotes string `json:"quorum_votes"`
+}
+
+var (
+	clusterQuorateDesc = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "cluster", "quorate"),
+		"Whether the cluster is quorate.",
+		nil,
+		nil,
+	)
+	clusterNodesTotalDesc = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "cluster", "nodes_total"),
+		"Total number of nodes in the cluster.",
+		nil,
+		nil,
+	)
+	clusterExpectedVotesDesc = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "cluster", "expected_votes"),
+		"Total expected votes in the cluster.",
+		nil,
+		nil,
+	)
+	nodeOnlineDesc = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "", "node_online"),
+		"Whether a node is online.",
+		[]string{"name", "nodeid"},
+		nil,
+	)
+)
+
+func (c *corosyncCollector) Update(client *Client, ch chan<- prometheus.Metric) error {
+	// Fetch cluster status for quorate, node count, and node online state.
+	statusBody, err := client.Get("/cluster/status")
+	if err != nil {
+		return fmt.Errorf("failed to get /cluster/status: %w", err)
+	}
+
+	var statusResp clusterStatusResponse
+	if err := json.Unmarshal(statusBody, &statusResp); err != nil {
+		return fmt.Errorf("failed to parse /cluster/status response: %w", err)
+	}
+
+	var nodeCount int
+	for _, entry := range statusResp.Data {
+		switch entry.Type {
+		case "cluster":
+			ch <- prometheus.MustNewConstMetric(clusterQuorateDesc, prometheus.GaugeValue, float64(entry.Quorate))
+		case "node":
+			nodeCount++
+			ch <- prometheus.MustNewConstMetric(
+				nodeOnlineDesc,
+				prometheus.GaugeValue,
+				float64(entry.Online),
+				entry.Name,
+				strconv.Itoa(entry.NodeID),
+			)
+		}
+	}
+
+	ch <- prometheus.MustNewConstMetric(clusterNodesTotalDesc, prometheus.GaugeValue, float64(nodeCount))
+
+	// Fetch cluster config nodes for expected votes.
+	configBody, err := client.Get("/cluster/config/nodes")
+	if err != nil {
+		return fmt.Errorf("failed to get /cluster/config/nodes: %w", err)
+	}
+
+	var configResp clusterConfigNodesResponse
+	if err := json.Unmarshal(configBody, &configResp); err != nil {
+		return fmt.Errorf("failed to parse /cluster/config/nodes response: %w", err)
+	}
+
+	var expectedVotes float64
+	for _, node := range configResp.Data {
+		votes, err := strconv.ParseFloat(node.QuorumVotes, 64)
+		if err != nil {
+			c.logger.Warn("failed to parse quorum_votes", "node", node.Node, "err", err)
+			continue
+		}
+		expectedVotes += votes
+	}
+
+	ch <- prometheus.MustNewConstMetric(clusterExpectedVotesDesc, prometheus.GaugeValue, expectedVotes)
+
+	return nil
+}

collector/corosync_test.go

@@ -0,0 +1,48 @@
+package collector
+
+import (
+	"log/slog"
+	"strings"
+	"testing"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/testutil"
+)
+
+func TestCorosyncCollector(t *testing.T) {
+	client := newTestClient(t, map[string]string{
+		"/cluster/status":       "cluster_status.json",
+		"/cluster/config/nodes": "cluster_config_nodes.json",
+	})
+
+	collector := newCorosyncCollector(slog.Default())
+	adapter := &testCollectorAdapter{client: client, collector: collector}
+
+	reg := prometheus.NewRegistry()
+	reg.MustRegister(adapter)
+
+	expected := `
+# HELP pve_cluster_expected_votes Total expected votes in the cluster.
+# TYPE pve_cluster_expected_votes gauge
+pve_cluster_expected_votes 5
+# HELP pve_cluster_nodes_total Total number of nodes in the cluster.
+# TYPE pve_cluster_nodes_total gauge
+pve_cluster_nodes_total 5
+# HELP pve_cluster_quorate Whether the cluster is quorate.
+# TYPE pve_cluster_quorate gauge
+pve_cluster_quorate 1
+# HELP pve_node_online Whether a node is online.
+# TYPE pve_node_online gauge
+pve_node_online{name="node01",nodeid="1"} 1
+pve_node_online{name="node02",nodeid="2"} 1
+pve_node_online{name="node03",nodeid="3"} 1
+pve_node_online{name="node04",nodeid="4"} 1
+pve_node_online{name="node05",nodeid="5"} 1
+`
+
+	if err := testutil.GatherAndCompare(reg, strings.NewReader(expected),
+		"pve_cluster_quorate", "pve_cluster_nodes_total", "pve_cluster_expected_votes", "pve_node_online",
+	); err != nil {
+		t.Errorf("unexpected metrics: %s", err)
+	}
+}

collector/fixtures/cluster_config_nodes.json

@@ -0,0 +1 @@
+{"data":[{"node":"node01","nodeid":"1","quorum_votes":"1"},{"node":"node02","nodeid":"2","quorum_votes":"1"},{"node":"node03","nodeid":"3","quorum_votes":"1"},{"node":"node04","nodeid":"4","quorum_votes":"1"},{"node":"node05","nodeid":"5","quorum_votes":"1"}]}