github.com/Systemnick/migrate@v3.5.4+incompatible/source/google_cloud_storage/storage.go (about)

     1  package googlecloudstorage
     2  
     3  import (
     4  	"fmt"
     5  	"io"
     6  	"net/url"
     7  	"os"
     8  	"path"
     9  	"strings"
    10  
    11  	"cloud.google.com/go/storage"
    12  	"github.com/golang-migrate/migrate/source"
    13  	"golang.org/x/net/context"
    14  	"google.golang.org/api/iterator"
    15  )
    16  
    17  func init() {
    18  	source.Register("gcs", &gcs{})
    19  }
    20  
    21  type gcs struct {
    22  	bucket     *storage.BucketHandle
    23  	prefix     string
    24  	migrations *source.Migrations
    25  }
    26  
    27  func (g *gcs) Open(folder string) (source.Driver, error) {
    28  	u, err := url.Parse(folder)
    29  	if err != nil {
    30  		return nil, err
    31  	}
    32  	client, err := storage.NewClient(context.Background())
    33  	if err != nil {
    34  		return nil, err
    35  	}
    36  	driver := gcs{
    37  		bucket:     client.Bucket(u.Host),
    38  		prefix:     strings.Trim(u.Path, "/") + "/",
    39  		migrations: source.NewMigrations(),
    40  	}
    41  	err = driver.loadMigrations()
    42  	if err != nil {
    43  		return nil, err
    44  	}
    45  	return &driver, nil
    46  }
    47  
    48  func (g *gcs) loadMigrations() error {
    49  	iter := g.bucket.Objects(context.Background(), &storage.Query{
    50  		Prefix:    g.prefix,
    51  		Delimiter: "/",
    52  	})
    53  	object, err := iter.Next()
    54  	for ; err == nil; object, err = iter.Next() {
    55  		_, fileName := path.Split(object.Name)
    56  		m, parseErr := source.DefaultParse(fileName)
    57  		if parseErr != nil {
    58  			continue
    59  		}
    60  		if !g.migrations.Append(m) {
    61  			return fmt.Errorf("unable to parse file %v", object.Name)
    62  		}
    63  	}
    64  	if err != iterator.Done {
    65  		return err
    66  	}
    67  	return nil
    68  }
    69  
    70  func (g *gcs) Close() error {
    71  	return nil
    72  }
    73  
    74  func (g *gcs) First() (uint, error) {
    75  	v, ok := g.migrations.First()
    76  	if !ok {
    77  		return 0, os.ErrNotExist
    78  	}
    79  	return v, nil
    80  }
    81  
    82  func (g *gcs) Prev(version uint) (uint, error) {
    83  	v, ok := g.migrations.Prev(version)
    84  	if !ok {
    85  		return 0, os.ErrNotExist
    86  	}
    87  	return v, nil
    88  }
    89  
    90  func (g *gcs) Next(version uint) (uint, error) {
    91  	v, ok := g.migrations.Next(version)
    92  	if !ok {
    93  		return 0, os.ErrNotExist
    94  	}
    95  	return v, nil
    96  }
    97  
    98  func (g *gcs) ReadUp(version uint) (io.ReadCloser, string, error) {
    99  	if m, ok := g.migrations.Up(version); ok {
   100  		return g.open(m)
   101  	}
   102  	return nil, "", os.ErrNotExist
   103  }
   104  
   105  func (g *gcs) ReadDown(version uint) (io.ReadCloser, string, error) {
   106  	if m, ok := g.migrations.Down(version); ok {
   107  		return g.open(m)
   108  	}
   109  	return nil, "", os.ErrNotExist
   110  }
   111  
   112  func (g *gcs) open(m *source.Migration) (io.ReadCloser, string, error) {
   113  	objectPath := path.Join(g.prefix, m.Raw)
   114  	reader, err := g.bucket.Object(objectPath).NewReader(context.Background())
   115  	if err != nil {
   116  		return nil, "", err
   117  	}
   118  	return reader, m.Identifier, nil
   119  }