feat: initialize independent Bell product skeleton (#9)

Bell/server/internal/platform/database.go

@@ -0,0 +1,30 @@
+package platform
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+func OpenDatabase(ctx context.Context, databaseURL string) (*pgxpool.Pool, error) {
+	poolConfig, err := pgxpool.ParseConfig(databaseURL)
+	if err != nil {
+		return nil, fmt.Errorf("parse Bell database URL: %w", err)
+	}
+	poolConfig.MaxConns = 8
+	poolConfig.MinConns = 1
+	poolConfig.MaxConnLifetime = 30 * time.Minute
+	pool, err := pgxpool.NewWithConfig(ctx, poolConfig)
+	if err != nil {
+		return nil, fmt.Errorf("open Bell database: %w", err)
+	}
+	pingCtx, cancel := context.WithTimeout(ctx, 5*time.Second)
+	defer cancel()
+	if err := pool.Ping(pingCtx); err != nil {
+		pool.Close()
+		return nil, fmt.Errorf("ping Bell database: %w", err)
+	}
+	return pool, nil
+}