Replace all chain namespaces with labels

api/metrics/README.md

@@ -0,0 +1,23 @@
+# Metrics
+
+```mermaid
+graph LR
+    A[avalanche] --> B[api]
+    A --> C[chain]
+    A --> D[db]
+    A --> E[health]
+    A --> F[network]
+    A --> G[process]
+    A --> H[requests]
+    A --> I[resource_tracker]
+    A --> J[responses]
+    A --> K[system_resources]
+    C -- $chainID --> L[avalanche]
+    C -- $chainID --> M[handler]
+    C -- $chainID --> N[meterchainvm]
+    C -- $chainID --> O[meterdagvm]
+    C -- $chainID --> P[meterdb]
+    C -- $chainID --> Q[proposervm]
+    C -- $chainID --> R[snowman]
+    C -- $chainID --> S[$vmID]
+```

api/metrics/gatherer_test.go

@@ -3,15 +3,7 @@
 
 package metrics
 
-import (
-	dto "github.com/prometheus/client_model/go"
-)
-
-var (
-	hello      = "hello"
-	world      = "world"
-	helloWorld = "hello_world"
-)
+import dto "github.com/prometheus/client_model/go"
 
 type testGatherer struct {
 	mfs []*dto.MetricFamily

api/metrics/label_gatherer.go

@@ -0,0 +1,93 @@
+// Copyright (C) 2019-2024, Ava Labs, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package metrics
+
+import (
+	"cmp"
+	"errors"
+	"fmt"
+	"slices"
+
+	"github.com/prometheus/client_golang/prometheus"
+
+	dto "github.com/prometheus/client_model/go"
+)
+
+var (
+	_ MultiGatherer = (*prefixGatherer)(nil)
+
+	errDuplicateGatherer = errors.New("attempt to register duplicate gatherer")
+)
+
+// NewLabelGatherer returns a new MultiGatherer that merges metrics by adding a
+// new label.
+func NewLabelGatherer(labelName string) MultiGatherer {
+	return &labelGatherer{
+		labelName: labelName,
+	}
+}
+
+type labelGatherer struct {
+	multiGatherer
+
+	labelName string
+}
+
+func (g *labelGatherer) Register(labelValue string, gatherer prometheus.Gatherer) error {
+	g.lock.Lock()
+	defer g.lock.Unlock()
+
+	if slices.Contains(g.names, labelValue) {
+		return fmt.Errorf("%w: for %q with label %q",
+			errDuplicateGatherer,
+			g.labelName,
+			labelValue,
+		)
+	}
+
+	g.names = append(g.names, labelValue)
+	g.gatherers = append(g.gatherers, &labeledGatherer{
+		labelName:  g.labelName,
+		labelValue: labelValue,
+		gatherer:   gatherer,
+	})
+	return nil
+}
+
+type labeledGatherer struct {
+	labelName  string
+	labelValue string
+	gatherer   prometheus.Gatherer
+}
+
+func (g *labeledGatherer) Gather() ([]*dto.MetricFamily, error) {
+	gatheredMetricFamilies, err := g.gatherer.Gather()
+	if err != nil {
+		return nil, err
+	}
+
+	for _, gatheredMetricFamily := range gatheredMetricFamilies {
+		if gatheredMetricFamily == nil {
+			continue
+		}
+
+		metrics := gatheredMetricFamily.Metric[:0]
+		for _, gatheredMetric := range gatheredMetricFamily.Metric {
+			if gatheredMetric == nil {
+				continue
+			}
+
+			gatheredMetric.Label = append(gatheredMetric.Label, &dto.LabelPair{
+				Name:  &g.labelName,
+				Value: &g.labelValue,
+			})
+			slices.SortFunc(gatheredMetric.Label, func(i, j *dto.LabelPair) int {
+				return cmp.Compare(i.GetName(), j.GetName())
+			})
+			metrics = append(metrics, gatheredMetric)
+		}
+		gatheredMetricFamily.Metric = metrics
+	}
+	return gatheredMetricFamilies, nil
+}

api/metrics/label_gatherer_test.go

@@ -0,0 +1,182 @@
+// Copyright (C) 2019-2024, Ava Labs, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package metrics
+
+import (
+	"testing"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/stretchr/testify/require"
+	"google.golang.org/protobuf/proto"
+
+	dto "github.com/prometheus/client_model/go"
+)
+
+func TestLabelGatherer_Gather(t *testing.T) {
+	require := require.New(t)
+
+	gatherer := NewLabelGatherer("smith")
+	require.NotNil(gatherer)
+
+	registerA := prometheus.NewRegistry()
+	require.NoError(gatherer.Register("rick", registerA))
+
+	registerB := prometheus.NewRegistry()
+	require.NoError(gatherer.Register("morty", registerB))
+
+	counterA := prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "counter",
+		Help: "help",
+	})
+	require.NoError(registerA.Register(counterA))
+
+	counterB := prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "counter",
+		Help: "help",
+	})
+	counterB.Inc()
+	require.NoError(registerB.Register(counterB))
+
+	metrics, err := gatherer.Gather()
+	require.NoError(err)
+	require.Equal(
+		[]*dto.MetricFamily{
+			{
+				Name: proto.String("counter"),
+				Help: proto.String("help"),
+				Type: dto.MetricType_COUNTER.Enum(),
+				Metric: []*dto.Metric{
+					{
+						Label: []*dto.LabelPair{
+							{
+								Name:  proto.String("smith"),
+								Value: proto.String("morty"),
+							},
+						},
+						Counter: &dto.Counter{
+							Value: proto.Float64(1),
+						},
+					},
+					{
+						Label: []*dto.LabelPair{
+							{
+								Name:  proto.String("smith"),
+								Value: proto.String("rick"),
+							},
+						},
+						Counter: &dto.Counter{
+							Value: proto.Float64(0),
+						},
+					},
+				},
+			},
+		},
+		metrics,
+	)
+}
+
+func TestLabelGatherer_Register(t *testing.T) {
+	tests := []struct {
+		name                  string
+		labelGatherer         *labelGatherer
+		labelValue            string
+		gatherer              prometheus.Gatherer
+		expectedErr           error
+		expectedLabelGatherer *labelGatherer
+	}{
+		{
+			name:          "first registration",
+			labelGatherer: &labelGatherer{},
+			labelValue:    "first",
+			gatherer:      &testGatherer{},
+			expectedErr:   nil,
+			expectedLabelGatherer: &labelGatherer{
+				multiGatherer: multiGatherer{
+					names: []string{"first"},
+					gatherers: prometheus.Gatherers{
+						&labeledGatherer{
+							labelValue: "first",
+							gatherer:   &testGatherer{},
+						},
+					},
+				},
+			},
+		},
+		{
+			name: "second registration",
+			labelGatherer: &labelGatherer{
+				multiGatherer: multiGatherer{
+					names: []string{"first"},
+					gatherers: prometheus.Gatherers{
+						&labeledGatherer{
+							labelValue: "first",
+							gatherer:   &testGatherer{},
+						},
+					},
+				},
+			},
+			labelValue: "second",
+			gatherer: &testGatherer{
+				mfs: []*dto.MetricFamily{{}},
+			},
+			expectedErr: nil,
+			expectedLabelGatherer: &labelGatherer{
+				multiGatherer: multiGatherer{
+					names: []string{"first", "second"},
+					gatherers: prometheus.Gatherers{
+						&labeledGatherer{
+							labelValue: "first",
+							gatherer:   &testGatherer{},
+						},
+						&labeledGatherer{
+							labelValue: "second",
+							gatherer: &testGatherer{
+								mfs: []*dto.MetricFamily{{}},
+							},
+						},
+					},
+				},
+			},
+		},
+		{
+			name: "conflicts with previous registration",
+			labelGatherer: &labelGatherer{
+				multiGatherer: multiGatherer{
+					names: []string{"first"},
+					gatherers: prometheus.Gatherers{
+						&labeledGatherer{
+							labelValue: "first",
+							gatherer:   &testGatherer{},
+						},
+					},
+				},
+			},
+			labelValue: "first",
+			gatherer: &testGatherer{
+				mfs: []*dto.MetricFamily{{}},
+			},
+			expectedErr: errDuplicateGatherer,
+			expectedLabelGatherer: &labelGatherer{
+				multiGatherer: multiGatherer{
+					names: []string{"first"},
+					gatherers: prometheus.Gatherers{
+						&labeledGatherer{
+							labelValue: "first",
+							gatherer:   &testGatherer{},
+						},
+					},
+				},
+			},
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			require := require.New(t)
+
+			err := test.labelGatherer.Register(test.labelValue, test.gatherer)
+			require.ErrorIs(err, test.expectedErr)
+			require.Equal(test.expectedLabelGatherer, test.labelGatherer)
+		})
+	}
+}