Codevault initial commit

internal/observability/metrics/metrics.go

@@ -0,0 +1,110 @@
+package metrics
+
+import (
+	"context"
+	"time"
+
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/metric"
+
+	"github.com/kanootoko/codevault/internal"
+)
+
+type Metrics struct {
+	HTTP  HTTPMetrics
+	Value ValueMetrics
+}
+
+func NewMetrics(meter metric.Meter) Metrics {
+	metrics := Metrics{
+		HTTP:  newHTTPMetrics(meter),
+		Value: newValueMetrics(meter),
+	}
+	addObservableMetrics(meter)
+	return metrics
+}
+
+type HTTPMetrics struct {
+	// Total HTTP requests with [route, status]
+	RequestsTotal metric.Int64Counter
+
+	// Request duration histogram in seconds with [route]
+	RequestDuration metric.Float64Histogram
+}
+
+func newHTTPMetrics(meter metric.Meter) HTTPMetrics {
+	requestsTotal, _ := meter.Int64Counter(
+		"http_requests_total",
+		metric.WithDescription("Total number of HTTP requests"),
+	)
+	requestDuration, _ := meter.Float64Histogram(
+		"http_request_duration_seconds",
+		metric.WithDescription("HTTP request duration histogram in seconds"),
+		metric.WithExplicitBucketBoundaries(0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1.0, 2.5, 5.0),
+		metric.WithUnit("s"),
+	)
+	return HTTPMetrics{
+		RequestsTotal:   requestsTotal,
+		RequestDuration: requestDuration,
+	}
+}
+
+type ValueMetrics struct {
+	// Successful getValue lookups, with [code]. Only successful lookups carry a
+	// code label since the set of stored codes is bounded, unlike guessed/failed ones.
+	GetSuccessTotal metric.Int64Counter
+
+	// Failed getValue lookups, with [reason] (not_found|rate_limited).
+	GetFailedTotal metric.Int64Counter
+
+	// Successful setValue writes, with [user].
+	SetSuccessTotal metric.Int64Counter
+
+	// Failed setValue writes, with [reason] (bad_request|unauthorized).
+	SetFailedTotal metric.Int64Counter
+}
+
+func newValueMetrics(meter metric.Meter) ValueMetrics {
+	getSuccessTotal, _ := meter.Int64Counter(
+		"codevault_get_value_success_total",
+		metric.WithDescription("Total number of successful getValue lookups"),
+	)
+	getFailedTotal, _ := meter.Int64Counter(
+		"codevault_get_value_failed_total",
+		metric.WithDescription("Total number of failed getValue lookups"),
+	)
+	setSuccessTotal, _ := meter.Int64Counter(
+		"codevault_set_value_success_total",
+		metric.WithDescription("Total number of successful setValue writes"),
+	)
+	setFailedTotal, _ := meter.Int64Counter(
+		"codevault_set_value_failed_total",
+		metric.WithDescription("Total number of failed setValue writes"),
+	)
+	return ValueMetrics{
+		GetSuccessTotal: getSuccessTotal,
+		GetFailedTotal:  getFailedTotal,
+		SetSuccessTotal: setSuccessTotal,
+		SetFailedTotal:  setFailedTotal,
+	}
+}
+
+func addObservableMetrics(meter metric.Meter) {
+	timeStarted := time.Now()
+	_, _ = meter.Int64ObservableGauge(
+		"startup_time",
+		metric.WithDescription("Startup timestamp"),
+		metric.WithInt64Callback(func(ctx context.Context, io metric.Int64Observer) error {
+			io.Observe(timeStarted.Unix(), metric.WithAttributes(attribute.String("version", internal.Version)))
+			return nil
+		}),
+	)
+	_, _ = meter.Int64ObservableGauge(
+		"last_update_time",
+		metric.WithDescription("Current timestamp"),
+		metric.WithInt64Callback(func(ctx context.Context, io metric.Int64Observer) error {
+			io.Observe(time.Now().Unix(), metric.WithAttributes(attribute.String("version", internal.Version)))
+			return nil
+		}),
+	)
+}