Merge pull request #57 from SamWhited/vfs

source/vfs: add virtual file system source

Makefile

@@ -1,4 +1,4 @@
-SOURCE ?= file go_bindata github aws_s3 google_cloud_storage
+SOURCE ?= file go_bindata github aws_s3 google_cloud_storage godoc_vfs
 DATABASE ?= postgres mysql redshift cassandra spanner cockroachdb clickhouse
 VERSION ?= $(shell git describe --tags 2>/dev/null | cut -c 2-)
 TEST_FLAGS ?=

cli/build_godoc-vfs.go

@@ -0,0 +1,7 @@
+// +build godoc_vfs
+
+package main
+
+import (
+	_ "github.com/golang-migrate/migrate/source/go_vfs"
+)

source/godoc_vfs/vfs.go

@@ -0,0 +1,137 @@
+// Package vfs contains a driver that reads migrations from a virtual file
+// system.
+//
+// Implementations of the filesystem interface that read from zip files and
+// maps, as well as the definition of the filesystem interface can be found in
+// the golang.org/x/tools/godoc/vfs package.
+package godoc_vfs
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"path"
+
+	"github.com/golang-migrate/migrate/source"
+	"golang.org/x/tools/godoc/vfs"
+)
+
+func init() {
+	source.Register("godoc-vfs", &VFS{})
+}
+
+// VFS is an implementation of driver that returns migrations from a virtual
+// file system.
+type VFS struct {
+	migrations *source.Migrations
+	fs         vfs.FileSystem
+	path       string
+}
+
+// Open implements the source.Driver interface for VFS.
+//
+// Calling this function panics, instead use the WithInstance function.
+// See the package level documentation for an example.
+func (b *VFS) Open(url string) (source.Driver, error) {
+	panic("not implemented")
+}
+
+// WithInstance creates a new driver from a virtual file system.
+// If a tree named searchPath exists in the virtual filesystem, WithInstance
+// searches for migration files there.
+// It defaults to "/".
+func WithInstance(fs vfs.FileSystem, searchPath string) (source.Driver, error) {
+	if searchPath == "" {
+		searchPath = "/"
+	}
+
+	bn := &VFS{
+		fs:         fs,
+		path:       searchPath,
+		migrations: source.NewMigrations(),
+	}
+
+	files, err := fs.ReadDir(searchPath)
+	if err != nil {
+		return nil, err
+	}
+
+	for _, fi := range files {
+		m, err := source.DefaultParse(fi.Name())
+		if err != nil {
+			continue // ignore files that we can't parse
+		}
+
+		if !bn.migrations.Append(m) {
+			return nil, fmt.Errorf("unable to parse file %v", fi)
+		}
+	}
+
+	return bn, nil
+}
+
+// Close implements the source.Driver interface for VFS.
+// It is a no-op and should not be used.
+func (b *VFS) Close() error {
+	return nil
+}
+
+// First returns the first migration verion found in the file system.
+// If no version is available os.ErrNotExist is returned.
+func (b *VFS) First() (version uint, err error) {
+	v, ok := b.migrations.First()
+	if !ok {
+		return 0, &os.PathError{"first", "<vfs>://" + b.path, os.ErrNotExist}
+	}
+	return v, nil
+}
+
+// Prev returns the previous version available to the driver.
+// If no previous version is available os.ErrNotExist is returned.
+func (b *VFS) Prev(version uint) (prevVersion uint, err error) {
+	v, ok := b.migrations.Prev(version)
+	if !ok {
+		return 0, &os.PathError{fmt.Sprintf("prev for version %v", version), "<vfs>://" + b.path, os.ErrNotExist}
+	}
+	return v, nil
+}
+
+// Prev returns the next version available to the driver.
+// If no previous version is available os.ErrNotExist is returned.
+func (b *VFS) Next(version uint) (nextVersion uint, err error) {
+	v, ok := b.migrations.Next(version)
+	if !ok {
+		return 0, &os.PathError{fmt.Sprintf("next for version %v", version), "<vfs>://" + b.path, os.ErrNotExist}
+	}
+	return v, nil
+}
+
+// ReadUp returns the up migration body and an identifier that helps with
+// finding this migration in the source.
+// If there is no up migration available for this version it returns
+// os.ErrNotExist.
+func (b *VFS) ReadUp(version uint) (r io.ReadCloser, identifier string, err error) {
+	if m, ok := b.migrations.Up(version); ok {
+		body, err := vfs.ReadFile(b.fs, path.Join(b.path, m.Raw))
+		if err != nil {
+			return nil, "", err
+		}
+		return ioutil.NopCloser(bytes.NewReader(body)), m.Identifier, nil
+	}
+	return nil, "", &os.PathError{fmt.Sprintf("read version %v", version), "<vfs>://" + b.path, os.ErrNotExist}
+}
+
+// ReadDown returns the down migration body and an identifier that helps with
+// finding this migration  in the source.
+func (b *VFS) ReadDown(version uint) (r io.ReadCloser, identifier string, err error) {
+	if m, ok := b.migrations.Down(version); ok {
+		body, err := vfs.ReadFile(b.fs, path.Join(b.path, m.Raw))
+		if err != nil {
+			return nil, "", err
+		}
+		return ioutil.NopCloser(bytes.NewReader(body)), m.Identifier, nil
+	}
+	return nil, "", &os.PathError{fmt.Sprintf("read version %v", version), "<vfs>://" + b.path, os.ErrNotExist}
+}

source/godoc_vfs/vfs_example_test.go

@@ -0,0 +1,30 @@
+package godoc_vfs_test
+
+import (
+	"github.com/golang-migrate/migrate"
+	"github.com/golang-migrate/migrate/source/godoc_vfs"
+	"golang.org/x/tools/godoc/vfs/mapfs"
+)
+
+func Example_mapfs() {
+	fs := mapfs.New(map[string]string{
+		"1_foobar.up.sql":   "1 up",
+		"1_foobar.down.sql": "1 down",
+		"3_foobar.up.sql":   "3 up",
+		"4_foobar.up.sql":   "4 up",
+		"4_foobar.down.sql": "4 down",
+		"5_foobar.down.sql": "5 down",
+		"7_foobar.up.sql":   "7 up",
+		"7_foobar.down.sql": "7 down",
+	})
+
+	d, err := godoc_vfs.WithInstance(fs, "")
+	if err != nil {
+		panic("bad migrations found!")
+	}
+	m, err := migrate.NewWithSourceInstance("godoc-vfs", d, "database://foobar")
+	if err != nil {
+		panic("error creating the migrations")
+	}
+	m.Up()
+}

source/godoc_vfs/vfs_test.go

@@ -0,0 +1,38 @@
+package godoc_vfs_test
+
+import (
+	"testing"
+
+	"github.com/golang-migrate/migrate/source/godoc_vfs"
+	st "github.com/golang-migrate/migrate/source/testing"
+	"golang.org/x/tools/godoc/vfs/mapfs"
+)
+
+func TestVFS(t *testing.T) {
+	fs := mapfs.New(map[string]string{
+		"1_foobar.up.sql":   "1 up",
+		"1_foobar.down.sql": "1 down",
+		"3_foobar.up.sql":   "3 up",
+		"4_foobar.up.sql":   "4 up",
+		"4_foobar.down.sql": "4 down",
+		"5_foobar.down.sql": "5 down",
+		"7_foobar.up.sql":   "7 up",
+		"7_foobar.down.sql": "7 down",
+	})
+
+	d, err := godoc_vfs.WithInstance(fs, "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	st.Test(t, d)
+}
+
+func TestOpen(t *testing.T) {
+	defer func() {
+		if r := recover(); r == nil {
+			t.Error("Expected Open to panic")
+		}
+	}()
+	b := &godoc_vfs.VFS{}
+	b.Open("")
+}