Add backend foundation and config-driven workbench

backend/internal/store/postgres/db.go

@@ -0,0 +1,46 @@
+package postgres
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+type Store struct {
+	pool *pgxpool.Pool
+}
+
+type Tx = pgx.Tx
+
+func Open(ctx context.Context, databaseURL string) (*pgxpool.Pool, error) {
+	pool, err := pgxpool.New(ctx, databaseURL)
+	if err != nil {
+		return nil, fmt.Errorf("open postgres pool: %w", err)
+	}
+
+	if err := pool.Ping(ctx); err != nil {
+		pool.Close()
+		return nil, fmt.Errorf("ping postgres: %w", err)
+	}
+	return pool, nil
+}
+
+func NewStore(pool *pgxpool.Pool) *Store {
+	return &Store{pool: pool}
+}
+
+func (s *Store) Pool() *pgxpool.Pool {
+	return s.pool
+}
+
+func (s *Store) Close() {
+	if s.pool != nil {
+		s.pool.Close()
+	}
+}
+
+func (s *Store) Begin(ctx context.Context) (pgx.Tx, error) {
+	return s.pool.Begin(ctx)
+}