query-orchestration/internal/database/migrations/migrations.go

package migrations

import (
	"context"
	"database/sql"
	"fmt"
	"log/slog"
	"path"

	"queryorchestration/internal/serviceconfig"
	"queryorchestration/internal/serviceconfig/database"

	"github.com/golang-migrate/migrate/v4"
	_ "github.com/golang-migrate/migrate/v4/database/postgres"
	_ "github.com/golang-migrate/migrate/v4/source/file"
	_ "github.com/lib/pq"
)

func createDB(cfg database.ConfigProvider) error {
	connStr := fmt.Sprintf("%s?%s", cfg.GetDBBaseURI(), cfg.GetDBOptsString())

	db, err := sql.Open(cfg.GetDBDriver(), connStr)
	if err != nil {
		return fmt.Errorf("error opening database: %v", err)
	}

	err = db.Ping()
	if err != nil {
		return fmt.Errorf("error pinging database: %v", err)
	}

	rs, err := db.Query(fmt.Sprintf("SELECT 'CREATE DATABASE %s' WHERE NOT EXISTS (SELECT FROM pg_database WHERE datname = '%s')", cfg.GetDBName(), cfg.GetDBName()))
	if err != nil {
		return fmt.Errorf("error creating database: %v", err)
	}

	if rs.Next() {
		slog.Info("database created", "name", cfg.GetDBName())
	} else {
		slog.Info("database already exists", "name", cfg.GetDBName())
	}

	return nil
}

func Run(ctx context.Context, cfg serviceconfig.ConfigProvider) error {
	err := createDB(cfg)
	if err != nil {
		return err
	}

	migPath := "file://" + path.Join(cfg.GetBasePath(), "database/migrations")
	m, err := migrate.New(
		migPath,
		cfg.GetDBURI(),
	)
	if err != nil {
		return fmt.Errorf("failed to create migrate instance: %v", err)
	}

	err = m.Up()
	if err == migrate.ErrNoChange {
		slog.Info("No migration changes required")
	} else if err != nil {
		return fmt.Errorf("failed to apply migrations: %v", err)
	} else {
		slog.Info("Migrations applied successfully!")
	}

	return nil
}