/
s3.go
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/
s3.go
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// The contents of this package are based on
// https://github.com/golang-migrate/migrate/tree/331a15d92a86e002ce5043e788cc2ca287ab0cc2/source/aws_s3
// with the intention of hopefully proposing that it be added to
// golang-migrate/migrate.
package awss3v2
import (
"context"
"fmt"
"io"
"net/url"
"os"
"path"
"strings"
"github.com/aws/aws-sdk-go-v2/aws"
"github.com/aws/aws-sdk-go-v2/config"
"github.com/aws/aws-sdk-go-v2/service/s3"
"github.com/golang-migrate/migrate/v4/source"
)
var (
_ctx context.Context = context.TODO()
)
func init() {
source.Register("s3", &s3Driver{})
}
// SetContext allows setting the context used internally since the
// golang-migrate/migrate/v4/source Driver interface does not
// require a context.Context argument while the inner aws-sdk-go-v2
// functions do. No effort is made to lock writes to this internal
// context, so thread safety is very much punted.
func SetContext(ctx context.Context) {
_ctx = ctx
}
type S3er interface {
ListObjectsV2(context.Context, *s3.ListObjectsV2Input, ...func(*s3.Options)) (*s3.ListObjectsV2Output, error)
GetObject(context.Context, *s3.GetObjectInput, ...func(*s3.Options)) (*s3.GetObjectOutput, error)
}
type s3Driver struct {
s3client S3er
cfg *Config
migrations *source.Migrations
}
type Config struct {
Bucket string
Prefix string
}
func (s *s3Driver) Open(folder string) (source.Driver, error) {
cfg, err := parseURI(folder)
if err != nil {
return nil, err
}
awsCfg, err := config.LoadDefaultConfig(_ctx)
if err != nil {
return nil, err
}
return WithInstance(s3.NewFromConfig(awsCfg), cfg)
}
func WithInstance(s3client S3er, cfg *Config) (source.Driver, error) {
driver := &s3Driver{
cfg: cfg,
s3client: s3client,
migrations: source.NewMigrations(),
}
if err := driver.loadMigrations(); err != nil {
return nil, err
}
return driver, nil
}
func parseURI(uri string) (*Config, error) {
u, err := url.Parse(uri)
if err != nil {
return nil, err
}
prefix := strings.Trim(u.Path, "/")
if prefix != "" {
prefix += "/"
}
return &Config{
Bucket: u.Host,
Prefix: prefix,
}, nil
}
func (s *s3Driver) loadMigrations() error {
output, err := s.s3client.ListObjectsV2(_ctx, &s3.ListObjectsV2Input{
Bucket: aws.String(s.cfg.Bucket),
Prefix: aws.String(s.cfg.Prefix),
Delimiter: aws.String("/"),
})
if err != nil {
return err
}
for _, object := range output.Contents {
_, fileName := path.Split(aws.ToString(object.Key))
m, err := source.DefaultParse(fileName)
if err != nil {
continue
}
if !s.migrations.Append(m) {
return fmt.Errorf("unable to parse file %v", aws.ToString(object.Key))
}
}
return nil
}
func (s *s3Driver) Close() error {
return nil
}
func (s *s3Driver) First() (uint, error) {
v, ok := s.migrations.First()
if !ok {
return 0, os.ErrNotExist
}
return v, nil
}
func (s *s3Driver) Prev(version uint) (uint, error) {
v, ok := s.migrations.Prev(version)
if !ok {
return 0, os.ErrNotExist
}
return v, nil
}
func (s *s3Driver) Next(version uint) (uint, error) {
v, ok := s.migrations.Next(version)
if !ok {
return 0, os.ErrNotExist
}
return v, nil
}
func (s *s3Driver) ReadUp(version uint) (io.ReadCloser, string, error) {
if m, ok := s.migrations.Up(version); ok {
return s.open(m)
}
return nil, "", os.ErrNotExist
}
func (s *s3Driver) ReadDown(version uint) (io.ReadCloser, string, error) {
if m, ok := s.migrations.Down(version); ok {
return s.open(m)
}
return nil, "", os.ErrNotExist
}
func (s *s3Driver) open(m *source.Migration) (io.ReadCloser, string, error) {
key := path.Join(s.cfg.Prefix, m.Raw)
object, err := s.s3client.GetObject(_ctx, &s3.GetObjectInput{
Bucket: aws.String(s.cfg.Bucket),
Key: aws.String(key),
})
if err != nil {
return nil, "", err
}
return object.Body, m.Identifier, nil
}