/
main.go
342 lines (296 loc) · 7.62 KB
/
main.go
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package main
import (
"bufio"
"compress/gzip"
"context"
"errors"
"fmt"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/session"
"github.com/aws/aws-sdk-go/service/s3"
"github.com/aws/aws-sdk-go/service/s3/s3manager"
"github.com/dustin/go-humanize"
"github.com/jessevdk/go-flags"
"golang.org/x/sync/errgroup"
"io"
"os"
"path"
"strings"
"time"
)
type Options struct {
Region string `short:"r" long:"region" description:"AWSリージョンを指定します"`
Temp string `short:"t" long:"temp" description:"S3Objectのダウンロード先を指定します"`
Concurrency int `short:"c" long:"concurrency" description:"S3Objectの並列ダウンロード数を指定します"`
Timeout time.Duration `short:"e" long:"timeout" description:"ファイル取得のタイムアウトを設定します"`
Verbose bool `short:"v" long:"verbose" description:"詳細な出力を標準エラーに出力します"`
}
var opts = Options{
Concurrency: 1,
Temp: path.Join(os.TempDir(), "s3cat"),
}
func logFatal(err error) {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
func logError(err error) {
fmt.Fprintln(os.Stderr, err)
}
func stdout(format string, a ...interface{}) {
fmt.Fprintf(os.Stdout, format, a...)
}
func stderr(format string, a ...interface{}) {
fmt.Fprintf(os.Stderr, format, a...)
}
func main() {
// Parse option
parser := flags.NewParser(&opts, flags.HelpFlag|flags.PassDoubleDash)
parser.Name = os.Args[0]
parser.Usage = "[OPTIONS] PATTERN..."
args, err := parser.Parse()
if err != nil {
logFatal(err)
}
if len(args) == 0 {
parser.WriteHelp(os.Stderr)
os.Exit(1)
}
if opts.Verbose {
stderr("%+v => %+v\n", opts, args)
}
// Parse pattern
inputs, err := parseArgs(args)
if err != nil {
logFatal(err)
}
// Context
var (
ctx = context.Background()
cancel context.CancelFunc
)
if opts.Timeout > 0 {
ctx, cancel = context.WithTimeout(ctx, opts.Timeout)
defer cancel()
}
// Prepare aws session
cfgs := make([]*aws.Config, 0)
if opts.Region != "" {
cfgs = append(cfgs, &aws.Config{
Region: &opts.Region,
})
}
sess, err := session.NewSession(cfgs...)
if err != nil {
logFatal(err)
}
// Patternに一致するObject一覧を取得
objects, err := listS3Objects(ctx, sess, inputs)
if err != nil {
logFatal(err)
}
// ローカルとの差分をチェック
for _, object := range objects {
// ローカルに同じサイズのファイルが有る場合のみローカルフラグを立てる
fi, err := os.Stat(object.LocalPath(opts.Temp))
object.local = err == nil && fi.Size() == *object.raw.Size
}
// ダウンロード一覧を表示する
var download uint64
for _, object := range objects {
if !object.local {
download += uint64(*object.raw.Size)
}
if opts.Verbose {
stderr("[%1s] /%s/%s\n",
func(local bool) string {
if local {
return ""
}
return "D"
}(object.local),
object.bucket,
*object.raw.Key)
}
}
if opts.Verbose {
stderr("Download to '%s'\n", opts.Temp)
}
// ダウンロードサイズを表示
stderr("Size : %s\n", humanize.Bytes(download))
// ダウンロード
var (
deg, childCtx = errgroup.WithContext(ctx)
dsem = make(chan struct{}, opts.Concurrency)
s3m = s3manager.NewDownloader(sess)
)
for _, object := range objects {
if object.local {
continue
}
dsem <- struct{}{}
deg.Go(func(ctx context.Context, object *objectWrapper) func() error {
return func() error {
fp := object.LocalPath(opts.Temp)
if opts.Verbose {
stderr("%s ... Downloading\n", fp)
}
defer func() {
if opts.Verbose {
stderr("%s ... Done\n", fp)
}
<-dsem
}()
// ディレクトリがなければ作る
dir := path.Dir(fp)
if fi, err := os.Stat(dir); os.IsNotExist(err) {
if err := os.MkdirAll(dir, 0755); err != nil {
logFatal(fmt.Errorf("failed to create directory : %w", err))
}
} else if err != nil {
logFatal(fmt.Errorf("failed to stat : %w", err))
} else if !fi.IsDir() {
logFatal(fmt.Errorf("'%s' is not a directory", dir))
}
// ファイルを作る
f, err := os.Create(fp)
if err != nil {
return fmt.Errorf("failed to create local file '%s' : %w", fp, err)
}
defer func() {
if err := f.Close(); err != nil {
logFatal(fmt.Errorf("failed to close file : %w", err))
}
}()
// ダウンロード
if _, err =
s3m.DownloadWithContext(
ctx,
f,
&s3.GetObjectInput{
Bucket: &object.bucket,
Key: object.raw.Key,
}); err != nil {
return fmt.Errorf("failed to download file '%s' : %w", fp, err)
}
return nil
}
}(childCtx, object))
}
if err := deg.Wait(); err != nil {
logFatal(err)
}
// 出力
for _, object := range objects {
func () {
fp := object.LocalPath(opts.Temp)
var reader io.Reader
if f, err := os.Open(fp); err != nil {
logFatal(fmt.Errorf("failed to open '%s' : %w", fp, err))
} else {
defer f.Close()
reader = f
}
if strings.HasSuffix(fp, ".gz") {
if reader, err = gzip.NewReader(reader); err != nil {
logFatal(fmt.Errorf("failed to open '%s' as gzip : %w", err))
}
}
scanner := bufio.NewScanner(reader)
for scanner.Scan() {
stdout("%s\n", scanner.Text())
}
}()
}
}
func parseArgs(args []string) ([]*s3.ListObjectsV2Input, error) {
inputs := make([]*s3.ListObjectsV2Input, 0)
for _, arg := range args {
bucket, prefix, err := parseArg(arg)
if err != nil {
return nil, err
}
inputs = append(inputs, &s3.ListObjectsV2Input{Bucket: &bucket, Prefix: &prefix})
}
return inputs, nil
}
func parseArg(arg string) (bucket, prefix string, err error) {
if !path.IsAbs(arg) {
err = errors.New("PATTERN must be a start with '/'")
return
}
var (
bb strings.Builder
pb strings.Builder
isBucket = true
)
r := strings.NewReader(arg[1:])
for {
b, rberr := r.ReadByte()
if rberr == io.EOF {
break
} else if rberr != nil {
err = fmt.Errorf("failed to parse PATTERN : %w", rberr)
return
}
if isBucket {
if b == '/' {
isBucket = false
} else {
bb.WriteByte(b)
}
} else {
pb.WriteByte(b)
}
}
return bb.String(), pb.String(), nil
}
type objectWrapper struct {
bucket string
raw *s3.Object
local bool
}
func (w *objectWrapper) LocalPath(tmp string) string {
return path.Join(tmp, w.bucket, *w.raw.Key)
}
func listS3Objects(ctx context.Context, sess *session.Session, inputs []*s3.ListObjectsV2Input) ([]*objectWrapper, error) {
if opts.Verbose {
stderr("Fetch S3 object list ")
}
defer func() {
if opts.Verbose {
stderr(" OK\n")
}
}()
s3c := s3.New(sess)
results := make([]*objectWrapper, 0)
for _, input := range inputs {
objects, err := listS3Object(ctx, s3c, input, nil)
if err != nil {
return nil, err
}
results = append(results, objects...)
}
return results, nil
}
func listS3Object(ctx context.Context, s3c *s3.S3, input *s3.ListObjectsV2Input, token *string) ([]*objectWrapper, error) {
if opts.Verbose {
stderr(".")
}
input.ContinuationToken = token
out, err := s3c.ListObjectsV2WithContext(ctx, input)
if err != nil {
return nil, fmt.Errorf("failed to list S3 objects : %w", err)
}
results := make([]*objectWrapper, len(out.Contents))
for i, object := range out.Contents {
results[i] = &objectWrapper{bucket: *input.Bucket, raw: object}
}
if out.NextContinuationToken != nil {
nextOut, err := listS3Object(ctx, s3c, input, out.NextContinuationToken)
if err != nil {
return nil, err
}
results = append(results, nextOut...)
}
return results, nil
}