billing docs service

api/billing/documents/internal/service/documents/metrics.go

@@ -0,0 +1,105 @@
+package documents
+
+import (
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+	documentsv1 "github.com/tech/sendico/pkg/proto/billing/documents/v1"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+var (
+	metricsOnce sync.Once
+
+	requestsTotal  *prometheus.CounterVec
+	requestLatency *prometheus.HistogramVec
+	batchSize      prometheus.Histogram
+	documentBytes  *prometheus.HistogramVec
+)
+
+func initMetrics() {
+	metricsOnce.Do(func() {
+		requestsTotal = promauto.NewCounterVec(
+			prometheus.CounterOpts{
+				Namespace: "billing",
+				Subsystem: "documents",
+				Name:      "requests_total",
+				Help:      "Total number of billing document requests processed.",
+			},
+			[]string{"call", "status", "doc_type"},
+		)
+
+		requestLatency = promauto.NewHistogramVec(
+			prometheus.HistogramOpts{
+				Namespace: "billing",
+				Subsystem: "documents",
+				Name:      "request_latency_seconds",
+				Help:      "Latency of billing document requests.",
+				Buckets:   prometheus.DefBuckets,
+			},
+			[]string{"call", "status", "doc_type"},
+		)
+
+		batchSize = promauto.NewHistogram(
+			prometheus.HistogramOpts{
+				Namespace: "billing",
+				Subsystem: "documents",
+				Name:      "batch_size",
+				Help:      "Number of payment references in batch resolution requests.",
+				Buckets:   []float64{0, 1, 2, 5, 10, 20, 50, 100, 250, 500},
+			},
+		)
+
+		documentBytes = promauto.NewHistogramVec(
+			prometheus.HistogramOpts{
+				Namespace: "billing",
+				Subsystem: "documents",
+				Name:      "document_bytes",
+				Help:      "Size of generated billing document payloads.",
+				Buckets:   prometheus.ExponentialBuckets(1024, 2, 10),
+			},
+			[]string{"doc_type"},
+		)
+	})
+}
+
+func observeRequest(call string, docType documentsv1.DocumentType, statusLabel string, took time.Duration) {
+	typeLabel := docTypeLabel(docType)
+	requestsTotal.WithLabelValues(call, statusLabel, typeLabel).Inc()
+	requestLatency.WithLabelValues(call, statusLabel, typeLabel).Observe(took.Seconds())
+}
+
+func observeBatchSize(size int) {
+	batchSize.Observe(float64(size))
+}
+
+func observeDocumentBytes(docType documentsv1.DocumentType, size int) {
+	documentBytes.WithLabelValues(docTypeLabel(docType)).Observe(float64(size))
+}
+
+func statusFromError(err error) string {
+	if err == nil {
+		return "success"
+	}
+	st, ok := status.FromError(err)
+	if !ok {
+		return "error"
+	}
+	code := st.Code()
+	if code == codes.OK {
+		return "success"
+	}
+	return strings.ToLower(code.String())
+}
+
+func docTypeLabel(docType documentsv1.DocumentType) string {
+	label := docType.String()
+	if label == "" {
+		return "DOCUMENT_TYPE_UNSPECIFIED"
+	}
+	return label
+}