cmd/gomote/put.go - build - Git at Google

 // Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 package main

 import (
 	"archive/tar"
 	"bytes"
 	"context"
 	"errors"
 	"flag"
 	"fmt"
 	"io"
 	"mime/multipart"
 	"net/http"
 	"net/url"
 	"os"
 	"path/filepath"
 	"regexp"
 	"strconv"
 	"strings"

 	"golang.org/x/build/internal/gomote/protos"
 	"golang.org/x/build/tarutil"
 	"golang.org/x/sync/errgroup"
 )

 // putTar a .tar.gz
 func putTar(args []string) error {
 	fs := flag.NewFlagSet("put", flag.ContinueOnError)
 	fs.Usage = func() {
 		fmt.Fprintln(os.Stderr, "puttar usage: gomote puttar [put-opts] [instance] <source>")
 		fmt.Fprintln(os.Stderr)
 		fmt.Fprintln(os.Stderr, "<source> may be one of:")
 		fmt.Fprintln(os.Stderr, "- A path to a local .tar.gz file.")
 		fmt.Fprintln(os.Stderr, "- A URL that points at a .tar.gz file.")
 		fmt.Fprintln(os.Stderr, "- The '-' character to indicate a .tar.gz file passed via stdin.")
 		fmt.Fprintln(os.Stderr, "- Git hash (min 7 characters) for the Go repository (extract a .tar.gz of the repository at that commit w/o history)")
 		fmt.Fprintln(os.Stderr)
 		fmt.Fprintln(os.Stderr, "Instance name is optional if a group is specified.")
 		fs.PrintDefaults()
 		os.Exit(1)
 	}
 	var dir string
 	fs.StringVar(&dir, "dir", "", "relative directory from buildlet's work dir to extra tarball into")

 	fs.Parse(args)

 	// Parse arguments.
 	var putSet []string
 	var src string
 	switch fs.NArg() {
 	case 1:
 		// Must be just the source, so we need an active group.
 		if activeGroup == nil {
 			fmt.Fprintln(os.Stderr, "no active group found; need an active group with only 1 argument")
 			fs.Usage()
 		}
 		for _, inst := range activeGroup.Instances {
 			putSet = append(putSet, inst)
 		}
 		src = fs.Arg(0)
 	case 2:
 		// Instance and source is specified.
 		putSet = []string{fs.Arg(0)}
 		src = fs.Arg(1)
 	case 0:
 		fmt.Fprintln(os.Stderr, "error: not enough arguments")
 		fs.Usage()
 	default:
 		fmt.Fprintln(os.Stderr, "error: too many arguments")
 		fs.Usage()
 	}

 	// Interpret source.
 	var putTarFn func(ctx context.Context, inst string) error
 	if src == "-" {
 		// We might have multiple readers, so slurp up STDIN
 		// and store it, then hand out bytes.Readers to everyone.
 		var buf bytes.Buffer
 		_, err := io.Copy(&buf, os.Stdin)
 		if err != nil {
 			return fmt.Errorf("reading stdin: %w", err)
 		}
 		sharedTarBuf := buf.Bytes()
 		putTarFn = func(ctx context.Context, inst string) error {
 			return doPutTar(ctx, inst, dir, bytes.NewReader(sharedTarBuf))
 		}
 	} else {
 		u, err := url.Parse(src)
 		if err != nil {
 			// The URL parser should technically accept any of these, so the fact that
 			// we failed means its *very* malformed.
 			return fmt.Errorf("malformed source: not a path, a URL, -, or a git hash")
 		}
 		if u.Scheme != "" || u.Host != "" {
 			// Probably a real URL.
 			putTarFn = func(ctx context.Context, inst string) error {
 				return doPutTarURL(ctx, inst, dir, u.String())
 			}
 		} else {
 			// Probably a path. Check if it exists.
 			_, err := os.Stat(src)
 			if os.IsNotExist(err) {
 				// It must be a git hash. Check if this actually matches a git hash.
 				if len(src) < 7 || len(src) > 40 || regexp.MustCompile("[^a-f0-9]").MatchString(src) {
 					return fmt.Errorf("malformed source: not a path, a URL, -, or a git hash")
 				}
 				putTarFn = func(ctx context.Context, inst string) error {
 					return doPutTarGoRev(ctx, inst, dir, src)
 				}
 			} else if err != nil {
 				return fmt.Errorf("failed to stat %q: %w", src, err)
 			} else {
 				// It's a path.
 				putTarFn = func(ctx context.Context, inst string) error {
 					f, err := os.Open(src)
 					if err != nil {
 						return fmt.Errorf("opening %q: %w", src, err)
 					}
 					defer f.Close()
 					return doPutTar(ctx, inst, dir, f)
 				}
 			}
 		}
 	}
 	eg, ctx := errgroup.WithContext(context.Background())
 	for _, inst := range putSet {
 		inst := inst
 		eg.Go(func() error {
 			return putTarFn(ctx, inst)
 		})
 	}
 	return eg.Wait()
 }

 func doPutTarURL(ctx context.Context, name, dir, tarURL string) error {
 	client := gomoteServerClient(ctx)
 	_, err := client.WriteTGZFromURL(ctx, &protos.WriteTGZFromURLRequest{
 		GomoteId:  name,
 		Directory: dir,
 		Url:       tarURL,
 	})
 	if err != nil {
 		return fmt.Errorf("unable to write tar to instance: %w", err)
 	}
 	return nil
 }

 func doPutTarGoRev(ctx context.Context, name, dir, rev string) error {
 	tarURL := "https://go.googlesource.com/go/+archive/" + rev + ".tar.gz"
 	if err := doPutTarURL(ctx, name, dir, tarURL); err != nil {
 		return err
 	}

 	// Put a VERSION file there too, to avoid git usage.
 	version := strings.NewReader("devel " + rev)
 	var vtar tarutil.FileList
 	vtar.AddRegular(&tar.Header{
 		Name: "VERSION",
 		Mode: 0644,
 		Size: int64(version.Len()),
 	}, int64(version.Len()), version)
 	tgz := vtar.TarGz()
 	defer tgz.Close()

 	client := gomoteServerClient(ctx)
 	resp, err := client.UploadFile(ctx, &protos.UploadFileRequest{})
 	if err != nil {
 		return fmt.Errorf("unable to request credentials for a file upload: %w", err)
 	}
 	if err := uploadToGCS(ctx, resp.GetFields(), tgz, resp.GetObjectName(), resp.GetUrl()); err != nil {
 		return fmt.Errorf("unable to upload version file to GCS: %w", err)
 	}
 	if _, err = client.WriteTGZFromURL(ctx, &protos.WriteTGZFromURLRequest{
 		GomoteId:  name,
 		Directory: dir,
 		Url:       fmt.Sprintf("%s%s", resp.GetUrl(), resp.GetObjectName()),
 	}); err != nil {
 		return fmt.Errorf("unable to write tar to instance: %w", err)
 	}
 	return nil
 }

 func doPutTar(ctx context.Context, name, dir string, tgz io.Reader) error {
 	client := gomoteServerClient(ctx)
 	resp, err := client.UploadFile(ctx, &protos.UploadFileRequest{})
 	if err != nil {
 		return fmt.Errorf("unable to request credentials for a file upload: %w", err)
 	}
 	if err := uploadToGCS(ctx, resp.GetFields(), tgz, resp.GetObjectName(), resp.GetUrl()); err != nil {
 		return fmt.Errorf("unable to upload file to GCS: %w", err)
 	}
 	if _, err := client.WriteTGZFromURL(ctx, &protos.WriteTGZFromURLRequest{
 		GomoteId:  name,
 		Directory: dir,
 		Url:       fmt.Sprintf("%s%s", resp.GetUrl(), resp.GetObjectName()),
 	}); err != nil {
 		return fmt.Errorf("unable to write tar to instance: %w", err)
 	}
 	return nil
 }

 // putBootstrap places the bootstrap version of go in the workdir
 func putBootstrap(args []string) error {
 	fs := flag.NewFlagSet("putbootstrap", flag.ContinueOnError)
 	fs.Usage = func() {
 		fmt.Fprintln(os.Stderr, "putbootstrap usage: gomote putbootstrap [instance]")
 		fmt.Fprintln(os.Stderr)
 		fmt.Fprintln(os.Stderr, "Instance name is optional if a group is specified.")
 		fs.PrintDefaults()
 		os.Exit(1)
 	}
 	fs.Parse(args)

 	var putSet []string
 	switch fs.NArg() {
 	case 0:
 		if activeGroup == nil {
 			fmt.Fprintln(os.Stderr, "no active group found; need an active group with only 1 argument")
 			fs.Usage()
 		}
 		for _, inst := range activeGroup.Instances {
 			putSet = append(putSet, inst)
 		}
 	case 1:
 		putSet = []string{fs.Arg(0)}
 	default:
 		fmt.Fprintln(os.Stderr, "error: too many arguments")
 		fs.Usage()
 	}

 	eg, ctx := errgroup.WithContext(context.Background())
 	for _, inst := range putSet {
 		inst := inst
 		eg.Go(func() error {
 			client := gomoteServerClient(ctx)
 			resp, err := client.AddBootstrap(ctx, &protos.AddBootstrapRequest{
 				GomoteId: inst,
 			})
 			if err != nil {
 				return fmt.Errorf("unable to add bootstrap version of Go to instance: %w", err)
 			}
 			if resp.GetBootstrapGoUrl() == "" {
 				fmt.Printf("No GoBootstrapURL defined for %q; ignoring. (may be baked into image)\n", inst)
 			}
 			return nil
 		})
 	}
 	return eg.Wait()
 }

 // put single file
 func put(args []string) error {
 	fs := flag.NewFlagSet("put", flag.ContinueOnError)
 	fs.Usage = func() {
 		fmt.Fprintln(os.Stderr, "put usage: gomote put [put-opts] [instance] <source or '-' for stdin> [destination]")
 		fmt.Fprintln(os.Stderr)
 		fmt.Fprintln(os.Stderr, "Instance name is optional if a group is specified.")
 		fs.PrintDefaults()
 		os.Exit(1)
 	}
 	modeStr := fs.String("mode", "", "Unix file mode (octal); default to source file mode")
 	fs.Parse(args)

 	if fs.NArg() == 0 {
 		fs.Usage()
 	}

 	ctx := context.Background()
 	var putSet []string
 	var src, dst string
 	if err := doPing(ctx, fs.Arg(0)); instanceDoesNotExist(err) {
 		// When there's no active group, this is just an error.
 		if activeGroup == nil {
 			return fmt.Errorf("instance %q: %w", fs.Arg(0), err)
 		}
 		// When there is an active group, this just means that we're going
 		// to use the group instead and assume the rest is a command.
 		for _, inst := range activeGroup.Instances {
 			putSet = append(putSet, inst)
 		}
 		src = fs.Arg(0)
 		if fs.NArg() == 2 {
 			dst = fs.Arg(1)
 		} else if fs.NArg() != 1 {
 			fmt.Fprintln(os.Stderr, "error: too many arguments")
 			fs.Usage()
 		}
 	} else if err == nil {
 		putSet = append(putSet, fs.Arg(0))
 		if fs.NArg() == 1 {
 			fmt.Fprintln(os.Stderr, "error: missing source")
 			fs.Usage()
 		}
 		src = fs.Arg(1)
 		if fs.NArg() == 3 {
 			dst = fs.Arg(2)
 		} else if fs.NArg() != 2 {
 			fmt.Fprintln(os.Stderr, "error: too many arguments")
 			fs.Usage()
 		}
 	} else {
 		return fmt.Errorf("checking instance %q: %w", fs.Arg(0), err)
 	}
 	if dst == "" {
 		if src == "-" {
 			return errors.New("must specify destination file name when source is standard input")
 		}
 		dst = filepath.Base(src)
 	}

 	var mode os.FileMode = 0666
 	if *modeStr != "" {
 		modeInt, err := strconv.ParseInt(*modeStr, 8, 64)
 		if err != nil {
 			return err
 		}
 		mode = os.FileMode(modeInt)
 		if !mode.IsRegular() {
 			return fmt.Errorf("bad mode: %v", mode)
 		}
 	}

 	var putFileFn func(context.Context, string) error
 	if src == "-" {
 		var buf bytes.Buffer
 		_, err := io.Copy(&buf, os.Stdin)
 		if err != nil {
 			return fmt.Errorf("reading from stdin: %w", err)
 		}
 		sharedFileBuf := buf.Bytes()
 		putFileFn = func(ctx context.Context, inst string) error {
 			return doPutFile(ctx, inst, bytes.NewReader(sharedFileBuf), dst, mode)
 		}
 	} else {
 		putFileFn = func(ctx context.Context, inst string) error {
 			f, err := os.Open(src)
 			if err != nil {
 				return err
 			}
 			defer f.Close()

 			if *modeStr == "" {
 				fi, err := f.Stat()
 				if err != nil {
 					return err
 				}
 				mode = fi.Mode()
 			}
 			return doPutFile(ctx, inst, f, dst, mode)
 		}
 	}

 	eg, ctx := errgroup.WithContext(ctx)
 	for _, inst := range putSet {
 		inst := inst
 		eg.Go(func() error {
 			return putFileFn(ctx, inst)
 		})
 	}
 	return eg.Wait()
 }

 func doPutFile(ctx context.Context, inst string, r io.Reader, dst string, mode os.FileMode) error {
 	client := gomoteServerClient(ctx)
 	resp, err := client.UploadFile(ctx, &protos.UploadFileRequest{})
 	if err != nil {
 		return fmt.Errorf("unable to request credentials for a file upload: %w", err)
 	}
 	err = uploadToGCS(ctx, resp.GetFields(), r, dst, resp.GetUrl())
 	if err != nil {
 		return fmt.Errorf("unable to upload file to GCS: %w", err)
 	}
 	_, err = client.WriteFileFromURL(ctx, &protos.WriteFileFromURLRequest{
 		GomoteId: inst,
 		Url:      fmt.Sprintf("%s%s", resp.GetUrl(), resp.GetObjectName()),
 		Filename: dst,
 		Mode:     uint32(mode),
 	})
 	if err != nil {
 		return fmt.Errorf("unable to write the file from URL: %w", err)
 	}
 	return nil
 }

 func uploadToGCS(ctx context.Context, fields map[string]string, file io.Reader, filename, url string) error {
 	buf := new(bytes.Buffer)
 	mw := multipart.NewWriter(buf)

 	for k, v := range fields {
 		if err := mw.WriteField(k, v); err != nil {
 			return fmt.Errorf("unable to write field: %w", err)
 		}
 	}
 	_, err := mw.CreateFormFile("file", filename)
 	if err != nil {
 		return fmt.Errorf("unable to create form file: %w", err)
 	}
 	// Write our own boundary to avoid buffering entire file into the multipart Writer
 	bound := fmt.Sprintf("\r\n--%s--\r\n", mw.Boundary())
 	req, err := http.NewRequestWithContext(ctx, "POST", url, io.NopCloser(io.MultiReader(buf, file, strings.NewReader(bound))))
 	if err != nil {
 		return fmt.Errorf("unable to create request: %w", err)
 	}
 	req.Header.Set("Content-Type", mw.FormDataContentType())
 	res, err := http.DefaultClient.Do(req)
 	if err != nil {
 		return fmt.Errorf("http request failed: %w", err)
 	}
 	if res.StatusCode != http.StatusNoContent {
 		return fmt.Errorf("http post failed: status code=%d", res.StatusCode)
 	}
 	return nil
 }
	// Copyright 2015 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	package main

	import (
	"archive/tar"
	"bytes"
	"context"
	"errors"
	"flag"
	"fmt"
	"io"
	"mime/multipart"
	"net/http"
	"net/url"
	"os"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"

	"golang.org/x/build/internal/gomote/protos"
	"golang.org/x/build/tarutil"
	"golang.org/x/sync/errgroup"
	)

	// putTar a .tar.gz
	func putTar(args []string) error {
	fs := flag.NewFlagSet("put", flag.ContinueOnError)
	fs.Usage = func() {
	fmt.Fprintln(os.Stderr, "puttar usage: gomote puttar [put-opts] [instance] <source>")
	fmt.Fprintln(os.Stderr)
	fmt.Fprintln(os.Stderr, "<source> may be one of:")
	fmt.Fprintln(os.Stderr, "- A path to a local .tar.gz file.")
	fmt.Fprintln(os.Stderr, "- A URL that points at a .tar.gz file.")
	fmt.Fprintln(os.Stderr, "- The '-' character to indicate a .tar.gz file passed via stdin.")
	fmt.Fprintln(os.Stderr, "- Git hash (min 7 characters) for the Go repository (extract a .tar.gz of the repository at that commit w/o history)")
	fmt.Fprintln(os.Stderr)
	fmt.Fprintln(os.Stderr, "Instance name is optional if a group is specified.")
	fs.PrintDefaults()
	os.Exit(1)
	}
	var dir string
	fs.StringVar(&dir, "dir", "", "relative directory from buildlet's work dir to extra tarball into")

	fs.Parse(args)

	// Parse arguments.
	var putSet []string
	var src string
	switch fs.NArg() {
	case 1:
	// Must be just the source, so we need an active group.
	if activeGroup == nil {
	fmt.Fprintln(os.Stderr, "no active group found; need an active group with only 1 argument")
	fs.Usage()
	}
	for _, inst := range activeGroup.Instances {
	putSet = append(putSet, inst)
	}
	src = fs.Arg(0)
	case 2:
	// Instance and source is specified.
	putSet = []string{fs.Arg(0)}
	src = fs.Arg(1)
	case 0:
	fmt.Fprintln(os.Stderr, "error: not enough arguments")
	fs.Usage()
	default:
	fmt.Fprintln(os.Stderr, "error: too many arguments")
	fs.Usage()
	}

	// Interpret source.
	var putTarFn func(ctx context.Context, inst string) error
	if src == "-" {
	// We might have multiple readers, so slurp up STDIN
	// and store it, then hand out bytes.Readers to everyone.
	var buf bytes.Buffer
	_, err := io.Copy(&buf, os.Stdin)
	if err != nil {
	return fmt.Errorf("reading stdin: %w", err)
	}
	sharedTarBuf := buf.Bytes()
	putTarFn = func(ctx context.Context, inst string) error {
	return doPutTar(ctx, inst, dir, bytes.NewReader(sharedTarBuf))
	}
	} else {
	u, err := url.Parse(src)
	if err != nil {
	// The URL parser should technically accept any of these, so the fact that
	// we failed means its very malformed.
	return fmt.Errorf("malformed source: not a path, a URL, -, or a git hash")
	}
	if u.Scheme != "" \|\| u.Host != "" {
	// Probably a real URL.
	putTarFn = func(ctx context.Context, inst string) error {
	return doPutTarURL(ctx, inst, dir, u.String())
	}
	} else {
	// Probably a path. Check if it exists.
	_, err := os.Stat(src)
	if os.IsNotExist(err) {
	// It must be a git hash. Check if this actually matches a git hash.
	if len(src) < 7 \|\| len(src) > 40 \|\| regexp.MustCompile("[^a-f0-9]").MatchString(src) {
	return fmt.Errorf("malformed source: not a path, a URL, -, or a git hash")
	}
	putTarFn = func(ctx context.Context, inst string) error {
	return doPutTarGoRev(ctx, inst, dir, src)
	}
	} else if err != nil {
	return fmt.Errorf("failed to stat %q: %w", src, err)
	} else {
	// It's a path.
	putTarFn = func(ctx context.Context, inst string) error {
	f, err := os.Open(src)
	if err != nil {
	return fmt.Errorf("opening %q: %w", src, err)
	}
	defer f.Close()
	return doPutTar(ctx, inst, dir, f)
	}
	}
	}
	}
	eg, ctx := errgroup.WithContext(context.Background())
	for _, inst := range putSet {
	inst := inst
	eg.Go(func() error {
	return putTarFn(ctx, inst)
	})
	}
	return eg.Wait()
	}

	func doPutTarURL(ctx context.Context, name, dir, tarURL string) error {
	client := gomoteServerClient(ctx)
	_, err := client.WriteTGZFromURL(ctx, &protos.WriteTGZFromURLRequest{
	GomoteId: name,
	Directory: dir,
	Url: tarURL,
	})
	if err != nil {
	return fmt.Errorf("unable to write tar to instance: %w", err)
	}
	return nil
	}

	func doPutTarGoRev(ctx context.Context, name, dir, rev string) error {
	tarURL := "https://go.googlesource.com/go/+archive/" + rev + ".tar.gz"
	if err := doPutTarURL(ctx, name, dir, tarURL); err != nil {
	return err
	}

	// Put a VERSION file there too, to avoid git usage.
	version := strings.NewReader("devel " + rev)
	var vtar tarutil.FileList
	vtar.AddRegular(&tar.Header{
	Name: "VERSION",
	Mode: 0644,
	Size: int64(version.Len()),
	}, int64(version.Len()), version)
	tgz := vtar.TarGz()
	defer tgz.Close()

	client := gomoteServerClient(ctx)
	resp, err := client.UploadFile(ctx, &protos.UploadFileRequest{})
	if err != nil {
	return fmt.Errorf("unable to request credentials for a file upload: %w", err)
	}
	if err := uploadToGCS(ctx, resp.GetFields(), tgz, resp.GetObjectName(), resp.GetUrl()); err != nil {
	return fmt.Errorf("unable to upload version file to GCS: %w", err)
	}
	if _, err = client.WriteTGZFromURL(ctx, &protos.WriteTGZFromURLRequest{
	GomoteId: name,
	Directory: dir,
	Url: fmt.Sprintf("%s%s", resp.GetUrl(), resp.GetObjectName()),
	}); err != nil {
	return fmt.Errorf("unable to write tar to instance: %w", err)
	}
	return nil
	}

	func doPutTar(ctx context.Context, name, dir string, tgz io.Reader) error {
	client := gomoteServerClient(ctx)
	resp, err := client.UploadFile(ctx, &protos.UploadFileRequest{})
	if err != nil {
	return fmt.Errorf("unable to request credentials for a file upload: %w", err)
	}
	if err := uploadToGCS(ctx, resp.GetFields(), tgz, resp.GetObjectName(), resp.GetUrl()); err != nil {
	return fmt.Errorf("unable to upload file to GCS: %w", err)
	}
	if _, err := client.WriteTGZFromURL(ctx, &protos.WriteTGZFromURLRequest{
	GomoteId: name,
	Directory: dir,
	Url: fmt.Sprintf("%s%s", resp.GetUrl(), resp.GetObjectName()),
	}); err != nil {
	return fmt.Errorf("unable to write tar to instance: %w", err)
	}
	return nil
	}

	// putBootstrap places the bootstrap version of go in the workdir
	func putBootstrap(args []string) error {
	fs := flag.NewFlagSet("putbootstrap", flag.ContinueOnError)
	fs.Usage = func() {
	fmt.Fprintln(os.Stderr, "putbootstrap usage: gomote putbootstrap [instance]")
	fmt.Fprintln(os.Stderr)
	fmt.Fprintln(os.Stderr, "Instance name is optional if a group is specified.")
	fs.PrintDefaults()
	os.Exit(1)
	}
	fs.Parse(args)

	var putSet []string
	switch fs.NArg() {
	case 0:
	if activeGroup == nil {
	fmt.Fprintln(os.Stderr, "no active group found; need an active group with only 1 argument")
	fs.Usage()
	}
	for _, inst := range activeGroup.Instances {
	putSet = append(putSet, inst)
	}
	case 1:
	putSet = []string{fs.Arg(0)}
	default:
	fmt.Fprintln(os.Stderr, "error: too many arguments")
	fs.Usage()
	}

	eg, ctx := errgroup.WithContext(context.Background())
	for _, inst := range putSet {
	inst := inst
	eg.Go(func() error {
	client := gomoteServerClient(ctx)
	resp, err := client.AddBootstrap(ctx, &protos.AddBootstrapRequest{
	GomoteId: inst,
	})
	if err != nil {
	return fmt.Errorf("unable to add bootstrap version of Go to instance: %w", err)
	}
	if resp.GetBootstrapGoUrl() == "" {
	fmt.Printf("No GoBootstrapURL defined for %q; ignoring. (may be baked into image)\n", inst)
	}
	return nil
	})
	}
	return eg.Wait()
	}

	// put single file
	func put(args []string) error {
	fs := flag.NewFlagSet("put", flag.ContinueOnError)
	fs.Usage = func() {
	fmt.Fprintln(os.Stderr, "put usage: gomote put [put-opts] [instance] <source or '-' for stdin> [destination]")
	fmt.Fprintln(os.Stderr)
	fmt.Fprintln(os.Stderr, "Instance name is optional if a group is specified.")
	fs.PrintDefaults()
	os.Exit(1)
	}
	modeStr := fs.String("mode", "", "Unix file mode (octal); default to source file mode")
	fs.Parse(args)

	if fs.NArg() == 0 {
	fs.Usage()
	}

	ctx := context.Background()
	var putSet []string
	var src, dst string
	if err := doPing(ctx, fs.Arg(0)); instanceDoesNotExist(err) {
	// When there's no active group, this is just an error.
	if activeGroup == nil {
	return fmt.Errorf("instance %q: %w", fs.Arg(0), err)
	}
	// When there is an active group, this just means that we're going
	// to use the group instead and assume the rest is a command.
	for _, inst := range activeGroup.Instances {
	putSet = append(putSet, inst)
	}
	src = fs.Arg(0)
	if fs.NArg() == 2 {
	dst = fs.Arg(1)
	} else if fs.NArg() != 1 {
	fmt.Fprintln(os.Stderr, "error: too many arguments")
	fs.Usage()
	}
	} else if err == nil {
	putSet = append(putSet, fs.Arg(0))
	if fs.NArg() == 1 {
	fmt.Fprintln(os.Stderr, "error: missing source")
	fs.Usage()
	}
	src = fs.Arg(1)
	if fs.NArg() == 3 {
	dst = fs.Arg(2)
	} else if fs.NArg() != 2 {
	fmt.Fprintln(os.Stderr, "error: too many arguments")
	fs.Usage()
	}
	} else {
	return fmt.Errorf("checking instance %q: %w", fs.Arg(0), err)
	}
	if dst == "" {
	if src == "-" {
	return errors.New("must specify destination file name when source is standard input")
	}
	dst = filepath.Base(src)
	}

	var mode os.FileMode = 0666
	if *modeStr != "" {
	modeInt, err := strconv.ParseInt(*modeStr, 8, 64)
	if err != nil {
	return err
	}
	mode = os.FileMode(modeInt)
	if !mode.IsRegular() {
	return fmt.Errorf("bad mode: %v", mode)
	}
	}

	var putFileFn func(context.Context, string) error
	if src == "-" {
	var buf bytes.Buffer
	_, err := io.Copy(&buf, os.Stdin)
	if err != nil {
	return fmt.Errorf("reading from stdin: %w", err)
	}
	sharedFileBuf := buf.Bytes()
	putFileFn = func(ctx context.Context, inst string) error {
	return doPutFile(ctx, inst, bytes.NewReader(sharedFileBuf), dst, mode)
	}
	} else {
	putFileFn = func(ctx context.Context, inst string) error {
	f, err := os.Open(src)
	if err != nil {
	return err
	}
	defer f.Close()

	if *modeStr == "" {
	fi, err := f.Stat()
	if err != nil {
	return err
	}
	mode = fi.Mode()
	}
	return doPutFile(ctx, inst, f, dst, mode)
	}
	}

	eg, ctx := errgroup.WithContext(ctx)
	for _, inst := range putSet {
	inst := inst
	eg.Go(func() error {
	return putFileFn(ctx, inst)
	})
	}
	return eg.Wait()
	}

	func doPutFile(ctx context.Context, inst string, r io.Reader, dst string, mode os.FileMode) error {
	client := gomoteServerClient(ctx)
	resp, err := client.UploadFile(ctx, &protos.UploadFileRequest{})
	if err != nil {
	return fmt.Errorf("unable to request credentials for a file upload: %w", err)
	}
	err = uploadToGCS(ctx, resp.GetFields(), r, dst, resp.GetUrl())
	if err != nil {
	return fmt.Errorf("unable to upload file to GCS: %w", err)
	}
	_, err = client.WriteFileFromURL(ctx, &protos.WriteFileFromURLRequest{
	GomoteId: inst,
	Url: fmt.Sprintf("%s%s", resp.GetUrl(), resp.GetObjectName()),
	Filename: dst,
	Mode: uint32(mode),
	})
	if err != nil {
	return fmt.Errorf("unable to write the file from URL: %w", err)
	}
	return nil
	}

	func uploadToGCS(ctx context.Context, fields map[string]string, file io.Reader, filename, url string) error {
	buf := new(bytes.Buffer)
	mw := multipart.NewWriter(buf)

	for k, v := range fields {
	if err := mw.WriteField(k, v); err != nil {
	return fmt.Errorf("unable to write field: %w", err)
	}
	}
	_, err := mw.CreateFormFile("file", filename)
	if err != nil {
	return fmt.Errorf("unable to create form file: %w", err)
	}
	// Write our own boundary to avoid buffering entire file into the multipart Writer
	bound := fmt.Sprintf("\r\n--%s--\r\n", mw.Boundary())
	req, err := http.NewRequestWithContext(ctx, "POST", url, io.NopCloser(io.MultiReader(buf, file, strings.NewReader(bound))))
	if err != nil {
	return fmt.Errorf("unable to create request: %w", err)
	}
	req.Header.Set("Content-Type", mw.FormDataContentType())
	res, err := http.DefaultClient.Do(req)
	if err != nil {
	return fmt.Errorf("http request failed: %w", err)
	}
	if res.StatusCode != http.StatusNoContent {
	return fmt.Errorf("http post failed: status code=%d", res.StatusCode)
	}
	return nil
	}