Add io/fs#FS Driver #471

Makefile

@@ -1,4 +1,4 @@
-SOURCE ?= file go_bindata github github_ee bitbucket aws_s3 google_cloud_storage godoc_vfs gitlab
+SOURCE ?= file go_bindata github github_ee bitbucket aws_s3 google_cloud_storage godoc_vfs gitlab iofs
 DATABASE ?= postgres mysql redshift cassandra spanner cockroachdb clickhouse mongodb sqlserver firebird neo4j
 DATABASE_TEST ?= $(DATABASE) sqlite sqlcipher
 VERSION ?= $(shell git describe --tags 2>/dev/null | cut -c 2-)

internal/cli/build_iofs.go

@@ -0,0 +1,8 @@
+// +build go1.16
+// +build iofs
+
+package cli
+
+import (
+	_ "github.com/golang-migrate/migrate/v4/source/iofs"
+)

source/errors.go

@@ -1,15 +1,18 @@
 package source
 
-import "os"
-
 // ErrDuplicateMigration is an error type for reporting duplicate migration
 // files.
 type ErrDuplicateMigration struct {
 	Migration
-	os.FileInfo
+	FileInfo
 }
 
 // Error implements error interface.
 func (e ErrDuplicateMigration) Error() string {
 	return "duplicate migration file: " + e.Name()
 }
+
+// FileInfo is the interface that extracts the minimum required function from os.FileInfo by ErrDuplicateMigration.
+type FileInfo interface {
+	Name() string
+}

source/iofs/README.md

@@ -0,0 +1,38 @@
+# iofs
+
+Driver with file system interface (`io/fs#FS`) supported from Go 1.16.
+
+This Driver cannot be used with Go versions 1.15 and below.
+
+## Usage
+
+Directory embedding example
+
+```go
+package main
+
+import (
+	"embed"
+	"log"
+
+	"github.com/golang-migrate/migrate/v4"
+	_ "github.com/golang-migrate/migrate/v4/database/postgres"
+	"github.com/golang-migrate/migrate/v4/source/iofs"
+)
+
+//go:embed migrations
+var fs embed.FS
+
+func main() {
+	d, err := iofs.WithInstance(fs, "migrations")
+	if err != nil {
+		log.Fatal(err)
+	}
+	m, err := migrate.NewWithSourceInstance("iofs", d, "postgres://postgres@localhost/postgres?sslmode=disable")
+	if err != nil {
+		log.Fatal(err)
+	}
+	err = m.Up()
+	// ...
+}
+```

source/iofs/iofs.go

@@ -0,0 +1,160 @@
+// +build go1.16
+
+package iofs
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"io/fs"
+	"path"
+	"strconv"
+
+	"github.com/golang-migrate/migrate/v4/source"
+)
+
+func init() {
+	source.Register("iofs", &Iofs{})
+}
+
+// Iofs is a source driver for io/fs#FS.
+type Iofs struct {
+	migrations *source.Migrations
+	fsys       fs.ReadDirFS
+	path       string
+}
+
+// Open by url does not supported with Iofs.
+func (i *Iofs) Open(url string) (source.Driver, error) {
+	return nil, errors.New("iofs driver does not support open by url")
+}
+
+// WithInstance wraps io/fs#FS as source.Driver.
+func WithInstance(fsys fs.ReadDirFS, path string) (source.Driver, error) {
+	var i Iofs
+	if err := i.Init(fsys, path); err != nil {
+		return nil, fmt.Errorf("failed to init driver with path %s: %w", path, err)
+	}
+	return &i, nil
+}
+
+// Init prepares not initialized Iofs instance to read migrations from a
+// fs.ReadDirFS instance and a relative path.
+func (p *Iofs) Init(fsys fs.ReadDirFS, path string) error {
+	entries, err := fsys.ReadDir(path)
+	if err != nil {
+		return err
+	}
+
+	ms := source.NewMigrations()
+	for _, e := range entries {
+		if e.IsDir() {
+			continue
+		}
+		m, err := source.DefaultParse(e.Name())
+		if err != nil {
+			continue
+		}
+		if !ms.Append(m) {
+			return source.ErrDuplicateMigration{
+				Migration: *m,
+				FileInfo:  e,
+			}
+		}
+	}
+
+	p.fsys = fsys
+	p.path = path
+	p.migrations = ms
+	return nil
+}
+
+// Close is part of source.Driver interface implementation. This is a no-op.
+func (p *Iofs) Close() error {
+	return nil
+}
+
+// First is part of source.Driver interface implementation.
+func (p *Iofs) First() (version uint, err error) {
+	if version, ok := p.migrations.First(); ok {
+		return version, nil
+	}
+	return 0, &fs.PathError{
+		Op:   "first",
+		Path: p.path,
+		Err:  fs.ErrNotExist,
+	}
+}
+
+// Prev is part of source.Driver interface implementation.
+func (p *Iofs) Prev(version uint) (prevVersion uint, err error) {
+	if version, ok := p.migrations.Prev(version); ok {
+		return version, nil
+	}
+	return 0, &fs.PathError{
+		Op:   "prev for version " + strconv.FormatUint(uint64(version), 10),
+		Path: p.path,
+		Err:  fs.ErrNotExist,
+	}
+}
+
+// Next is part of source.Driver interface implementation.
+func (p *Iofs) Next(version uint) (nextVersion uint, err error) {
+	if version, ok := p.migrations.Next(version); ok {
+		return version, nil
+	}
+	return 0, &fs.PathError{
+		Op:   "next for version " + strconv.FormatUint(uint64(version), 10),
+		Path: p.path,
+		Err:  fs.ErrNotExist,
+	}
+}
+
+// ReadUp is part of source.Driver interface implementation.
+func (p *Iofs) ReadUp(version uint) (r io.ReadCloser, identifier string, err error) {
+	if m, ok := p.migrations.Up(version); ok {
+		body, err := p.open(path.Join(p.path, m.Raw))
+		if err != nil {
+			return nil, "", err
+		}
+		return body, m.Identifier, nil
+	}
+	return nil, "", &fs.PathError{
+		Op:   "read up for version " + strconv.FormatUint(uint64(version), 10),
+		Path: p.path,
+		Err:  fs.ErrNotExist,
+	}
+}
+
+// ReadDown is part of source.Driver interface implementation.
+func (p *Iofs) ReadDown(version uint) (r io.ReadCloser, identifier string, err error) {
+	if m, ok := p.migrations.Down(version); ok {
+		body, err := p.open(path.Join(p.path, m.Raw))
+		if err != nil {
+			return nil, "", err
+		}
+		return body, m.Identifier, nil
+	}
+	return nil, "", &fs.PathError{
+		Op:   "read down for version " + strconv.FormatUint(uint64(version), 10),
+		Path: p.path,
+		Err:  fs.ErrNotExist,
+	}
+}
+
+func (p *Iofs) open(path string) (fs.File, error) {
+	f, err := p.fsys.Open(path)
+	if err == nil {
+		return f, nil
+	}
+	// Some non-standard file systems may return errors that don't include the path, that
+	// makes debugging harder.
+	if !errors.As(err, new(*fs.PathError)) {
+		err = &fs.PathError{
+			Op:   "open",
+			Path: path,
+			Err:  err,
+		}
+	}
+	return nil, err
+}

source/iofs/iofs_test.go

@@ -0,0 +1,31 @@
+// +build go1.16
+
+package iofs_test
+
+import (
+	"embed"
+	"testing"
+
+	"github.com/golang-migrate/migrate/v4/source/iofs"
+	st "github.com/golang-migrate/migrate/v4/source/testing"
+)
+
+//go:embed testdata
+var fs embed.FS
+
+func Test(t *testing.T) {
+	d, err := iofs.WithInstance(fs, "testdata")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	st.Test(t, d)
+}
+
+func TestOpen(t *testing.T) {
+	i := new(iofs.Iofs)
+	_, err := i.Open("")
+	if err == nil {
+		t.Fatal("iofs driver does not support open by url")
+	}
+}

source/iofs/testdata/1_foobar.down.sql

@@ -0,0 +1 @@
+1 down

source/iofs/testdata/1_foobar.up.sql

@@ -0,0 +1 @@
+1 up

source/iofs/testdata/3_foobar.up.sql

@@ -0,0 +1 @@
+3 up

source/iofs/testdata/4_foobar.down.sql

@@ -0,0 +1 @@
+4 down

source/iofs/testdata/4_foobar.up.sql

@@ -0,0 +1 @@
+4 up

source/iofs/testdata/5_foobar.down.sql

@@ -0,0 +1 @@
+5 down

source/iofs/testdata/7_foobar.down.sql

@@ -0,0 +1 @@
+7 down

source/iofs/testdata/7_foobar.up.sql

@@ -0,0 +1 @@
+7 up