migrations.go

package main

import (
	"database/sql"
	"io/ioutil"
	"log"
	"path/filepath"
	"regexp"
	"strconv"

	"github.com/GuiaBolso/darwin"
	"gopkg.in/yaml.v2"
)

const migrationsDir = "migrations"

type migrationSource struct {
	Script string
}

var fileNameRegexp = regexp.MustCompile("^([0-9]+)_(.+)\\.yaml$")

func loadMigrations(db *sql.DB) ([]darwin.Migration, error) {
	filePaths, globErr := filepath.Glob(filepath.Join(migrationsDir, "[0-9]*.yaml"))
	if nil != globErr {
		return nil, globErr
	}

	migrations := make([]darwin.Migration, 0, len(filePaths))

	for _, fullFileName := range filePaths {
		fileName := filepath.Base(fullFileName)
		matches := fileNameRegexp.FindStringSubmatch(fileName)
		versionStr := matches[1]
		description := matches[2]
		version, _ := strconv.ParseFloat(versionStr, 10)

		yamlData, readErr := ioutil.ReadFile(fullFileName)
		if nil != readErr {
			return nil, readErr
		}

		var source migrationSource

		if err := yaml.Unmarshal(yamlData, &source); nil != err {
			return nil, err
		}

		migrations = append(migrations, darwin.Migration{
			Version:     version,
			Description: description,
			Script:      source.Script,
		})
	}

	return migrations, nil
}

func logMigration(infoChan <-chan darwin.MigrationInfo) {
	log.Printf("Migration is started")
	for info := range infoChan {
		if nil == info.Error {
			log.Printf(
				`Migration %f "%s" is %s`,
				info.Migration.Version,
				info.Migration.Description,
				info.Status,
			)
		} else {
			log.Printf("Migration error: %v", info.Error)
		}
	}
	log.Printf("Migration is ended")
}

func appleMigrations(db *sql.DB) error {
	migrations, loadErr := loadMigrations(db)
	if nil != loadErr {
		return loadErr
	}

	driver := darwin.NewGenericDriver(db, darwin.PostgresDialect{})

	infoChan := make(chan darwin.MigrationInfo)

	go logMigration(infoChan)

	return darwin.Migrate(driver, migrations, infoChan)
}