Align metric names with Prometheus naming conventions

Use base units, export cumulative values as _total counters, update docs, dashboards and rules.

metrics/pve_metrics_naming_test.go

@@ -0,0 +1,72 @@
+package metrics
+
+import (
+	"testing"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/testutil/promlint"
+)
+
+// Verifies that all exported PVE metrics follow the Prometheus naming conventions
+// (base units, '_total' suffix on counters, '_info' suffix on info metrics, ...)
+// so that tools such as promtool or Grafana do not report naming problems.
+func TestPveMetricNamesFollowPrometheusConventions(t *testing.T) {
+	registry := prometheus.NewRegistry()
+
+	// Collectors register their metrics on the default registerer, so it is
+	// temporarily replaced by a dedicated registry.
+	defaultRegisterer := prometheus.DefaultRegisterer
+	prometheus.DefaultRegisterer = registry
+	defer func() { prometheus.DefaultRegisterer = defaultRegisterer }()
+
+	// Collector constructors only create metrics, the API client is used during
+	// collection only, so a nil client is enough here.
+	ttlRegistry := NewTTLRegistry()
+	NewPveClusterStateCollector(nil, ttlRegistry)
+	NewPveNodeStatusCollector(nil, ttlRegistry)
+	NewPveSubscriptionCollector(nil, ttlRegistry)
+	NewPveNodeDiskCollector(nil, ttlRegistry)
+	NewPveNodeZfsCollector(nil, ttlRegistry)
+	NewPveSdnCollector(nil, ttlRegistry)
+	NewPveStorageCollector(nil, ttlRegistry)
+	NewPveContainerCollector(nil, ttlRegistry)
+	NewPveVirtualMachineCollector(nil, ttlRegistry)
+
+	// Metric vectors are exported only once they hold a label set.
+	for _, metric := range ttlRegistry.metrics {
+		switch m := metric.(type) {
+		case *TTLGaugeVec:
+			m.With(emptyLabels(m.labelNames)).Set(0)
+		case *TTLCounterVec:
+			m.With(emptyLabels(m.labelNames)).Set(0)
+		default:
+			t.Fatalf("Unknown TTL metric type %T.", metric)
+		}
+	}
+
+	families, err := registry.Gather()
+	if err != nil {
+		t.Fatalf("Unable to gather metrics. Error: %s.", err)
+	}
+	if len(families) != len(ttlRegistry.metrics) {
+		t.Fatalf("Gathered %d metric families but %d metrics are registered.", len(families), len(ttlRegistry.metrics))
+	}
+
+	problems, err := promlint.NewWithMetricFamilies(families).Lint()
+	if err != nil {
+		t.Fatalf("Unable to lint metrics. Error: %s.", err)
+	}
+
+	for _, problem := range problems {
+		t.Errorf("Metric '%s' violates the Prometheus naming conventions: %s.", problem.Metric, problem.Text)
+	}
+}
+
+// emptyLabels builds a label set with all given label names set to an empty value.
+func emptyLabels(labelNames []string) prometheus.Labels {
+	labels := prometheus.Labels{}
+	for _, name := range labelNames {
+		labels[name] = ""
+	}
+	return labels
+}