chore: establish local platform baseline

internal/database/postgres.go

@@ -0,0 +1,21 @@
+package database
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+func Open(ctx context.Context, databaseURL, applicationName string) (*pgxpool.Pool, error) {
+	poolConfig, err := pgxpool.ParseConfig(databaseURL)
+	if err != nil {
+		return nil, fmt.Errorf("parse database configuration: %w", err)
+	}
+	poolConfig.ConnConfig.RuntimeParams["application_name"] = applicationName
+	pool, err := pgxpool.NewWithConfig(ctx, poolConfig)
+	if err != nil {
+		return nil, fmt.Errorf("create database pool: %w", err)
+	}
+	return pool, nil
+}

internal/database/transaction.go

@@ -0,0 +1,24 @@
+package database
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+func Transact(ctx context.Context, pool *pgxpool.Pool, fn func(pgx.Tx) error) error {
+	tx, err := pool.BeginTx(ctx, pgx.TxOptions{})
+	if err != nil {
+		return fmt.Errorf("begin transaction: %w", err)
+	}
+	defer func() { _ = tx.Rollback(context.Background()) }()
+	if err := fn(tx); err != nil {
+		return err
+	}
+	if err := tx.Commit(ctx); err != nil {
+		return fmt.Errorf("commit transaction: %w", err)
+	}
+	return nil
+}