CUB-124: scaffold Control Center Go backend

go-backend/internal/db/db.go

@@ -0,0 +1,62 @@
+// Package db provides PostgreSQL connection management using pgx.
+package db
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"time"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+// Pool wraps a pgx connection pool with lifecycle helpers.
+type Pool struct {
+	*pgxpool.Pool
+}
+
+// New creates a connection pool from a PostgreSQL DSN.
+func New(dsn string) (*Pool, error) {
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
+	cfg, err := pgxpool.ParseConfig(dsn)
+	if err != nil {
+		return nil, fmt.Errorf("parse pgx config: %w", err)
+	}
+
+	// Sensible defaults
+	cfg.MaxConns = 20
+	cfg.MinConns = 2
+	cfg.MaxConnLifetime = 30 * time.Minute
+	cfg.MaxConnIdleTime = 10 * time.Minute
+	cfg.HealthCheckPeriod = 5 * time.Second
+
+	pool, err := pgxpool.NewWithConfig(ctx, cfg)
+	if err != nil {
+		return nil, fmt.Errorf("create pgx pool: %w", err)
+	}
+
+	if err := pool.Ping(ctx); err != nil {
+		pool.Close()
+		return nil, fmt.Errorf("ping database: %w", err)
+	}
+
+	slog.Info("database connected", "pool", cfg.ConnConfig.Database)
+	return &Pool{Pool: pool}, nil
+}
+
+// Close shuts down the pool gracefully.
+func (p *Pool) Close() {
+	if p.Pool != nil {
+		p.Pool.Close()
+		slog.Info("database pool closed")
+	}
+}
+
+// Health returns nil if the database is reachable.
+func (p *Pool) Health(ctx context.Context) error {
+	ctx, cancel := context.WithTimeout(ctx, 3*time.Second)
+	defer cancel()
+	return p.Ping(ctx)
+}