(Feat): Initial Commit

internal/metrics/service.go

@@ -0,0 +1,46 @@
+package metrics
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+
+	"allaboutapps.dev/aw/go-starter/internal/config"
+	"allaboutapps.dev/aw/go-starter/internal/metrics/users"
+	"allaboutapps.dev/aw/go-starter/internal/util"
+	"github.com/dlmiddlecote/sqlstats"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+type Service struct {
+	config config.Server
+	db     *sql.DB
+}
+
+func New(config config.Server, db *sql.DB) (*Service, error) {
+	return &Service{
+		config: config,
+		db:     db,
+	}, nil
+}
+
+func (s *Service) RegisterMetrics(ctx context.Context) error {
+	log := util.LogFromContext(ctx)
+
+	var metrics []prometheus.Collector
+
+	// custom metrics
+	metrics = append(metrics, users.Metrics(ctx, users.NewDatabaseMetricsCollector(s.db))...)
+
+	// sqlstats metrics, see https://github.com/dlmiddlecote/sqlstats?tab=readme-ov-file#exposed-metrics for the exposed metrics
+	metrics = append(metrics, sqlstats.NewStatsCollector(s.config.Database.Database, s.db))
+
+	for _, metric := range metrics {
+		if err := prometheus.Register(metric); err != nil {
+			log.Error().Err(err).Msg("Failed to register metric")
+			return fmt.Errorf("failed to register metric: %w", err)
+		}
+	}
+
+	return nil
+}

internal/metrics/users/collector.go

@@ -0,0 +1,29 @@
+package users
+
+import (
+	"context"
+	"database/sql"
+
+	"allaboutapps.dev/aw/go-starter/internal/models"
+	"allaboutapps.dev/aw/go-starter/internal/util"
+)
+
+type DatabaseMetricsCollector struct {
+	db *sql.DB
+}
+
+func NewDatabaseMetricsCollector(db *sql.DB) *DatabaseMetricsCollector {
+	return &DatabaseMetricsCollector{db: db}
+}
+
+func (c DatabaseMetricsCollector) GetTotalUsersCount(ctx context.Context) float64 {
+	log := util.LogFromContext(ctx)
+
+	count, err := models.Users().Count(ctx, c.db)
+	if err != nil {
+		log.Error().Err(err).Msg("Failed to total user count")
+		return 0
+	}
+
+	return float64(count)
+}

internal/metrics/users/metrics.go

@@ -0,0 +1,27 @@
+package users
+
+import (
+	"context"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+type MetricsCollector interface {
+	GetTotalUsersCount(ctx context.Context) float64
+}
+
+const (
+	MetricNameTotalUsers = "total_users"
+)
+
+func Metrics(ctx context.Context, collector MetricsCollector) []prometheus.Collector {
+	return []prometheus.Collector{
+		prometheus.NewGaugeFunc(
+			prometheus.GaugeOpts{
+				Name: MetricNameTotalUsers,
+				Help: "Total users",
+			},
+			func() float64 { return collector.GetTotalUsersCount(ctx) },
+		),
+	}
+}