shim: support shim v2 logging plugin

Now kata shim only supports stdout/stderr of fifo from
containerd/CRI-O, but shim v2 supports logging plugins,
and nerdctl default will use the binary schema for logs.

This commit will add the others type of log plugins:

- file
- binary

In case of binary, kata shim will receive a stdout/stderr like:

binary:///nerdctl?_NERDCTL_INTERNAL_LOGGING=/var/lib/nerdctl/1935db59

That means the nerdctl process will handle the logs(stdout/stderr)

Fixes: #4420

Signed-off-by: Bin Liu <bin@hyper.sh>

src/runtime/pkg/containerd-shim-v2/service.go

@@ -7,6 +7,7 @@ package containerdshim
 
 import (
 	"context"
+	"fmt"
 	"io"
 	"os"
 	sysexec "os/exec"
@@ -83,6 +84,11 @@ func New(ctx context.Context, id string, publisher cdshim.Publisher, shutdown fu
 	vci.SetLogger(ctx, shimLog)
 	katautils.SetLogger(ctx, shimLog, shimLog.Logger.Level)
 
+	ns, found := namespaces.Namespace(ctx)
+	if !found {
+		return nil, fmt.Errorf("shim namespace cannot be empty")
+	}
+
 	s := &service{
 		id:         id,
 		pid:        uint32(os.Getpid()),
@@ -91,6 +97,7 @@ func New(ctx context.Context, id string, publisher cdshim.Publisher, shutdown fu
 		events:     make(chan interface{}, chSize),
 		ec:         make(chan exit, bufferSize),
 		cancel:     shutdown,
+		namespace:  ns,
 	}
 
 	go s.processExits()
@@ -129,6 +136,9 @@ type service struct {
 
 	id string
 
+	// Namespace from upper container engine
+	namespace string
+
 	mu          sync.Mutex
 	eventSendMu sync.Mutex
 

src/runtime/pkg/containerd-shim-v2/shim_io_binary.go

@@ -0,0 +1,216 @@
+// Copyright (c) 2022 Ant Group
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+package containerdshim
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/url"
+	"os"
+	"syscall"
+	"time"
+
+	"golang.org/x/sys/execabs"
+
+	"github.com/hashicorp/go-multierror"
+)
+
+const (
+	binaryIOProcTermTimeout = 12 * time.Second // Give logger process solid 10 seconds for cleanup
+)
+
+var (
+	_ IO = &binaryIO{}
+)
+
+// binaryIO related code is from https://github.com/containerd/containerd/blob/v1.6.6/pkg/process/io.go#L311
+type binaryIO struct {
+	cmd      *execabs.Cmd
+	out, err *pipe
+}
+
+// https://github.com/containerd/containerd/blob/v1.6.6/pkg/process/io.go#L248
+func newBinaryIO(ctx context.Context, ns, id string, uri *url.URL) (bio *binaryIO, err error) {
+	var closers []func() error
+	defer func() {
+		if err == nil {
+			return
+		}
+		result := multierror.Append(err)
+		for _, fn := range closers {
+			result = multierror.Append(result, fn())
+		}
+		err = multierror.Flatten(result)
+	}()
+
+	out, err := newPipe()
+	if err != nil {
+		return nil, fmt.Errorf("failed to create stdout pipes: %w", err)
+	}
+	closers = append(closers, out.Close)
+
+	serr, err := newPipe()
+	if err != nil {
+		return nil, fmt.Errorf("failed to create stderr pipes: %w", err)
+	}
+	closers = append(closers, serr.Close)
+
+	r, w, err := os.Pipe()
+	if err != nil {
+		return nil, err
+	}
+	closers = append(closers, r.Close, w.Close)
+
+	cmd := newBinaryCmd(uri, id, ns)
+	cmd.ExtraFiles = append(cmd.ExtraFiles, out.r, serr.r, w)
+	// don't need to register this with the reaper or wait when
+	// running inside a shim
+	if err := cmd.Start(); err != nil {
+		return nil, fmt.Errorf("failed to start binary process: %w", err)
+	}
+	closers = append(closers, func() error { return cmd.Process.Kill() })
+
+	// close our side of the pipe after start
+	if err := w.Close(); err != nil {
+		return nil, fmt.Errorf("failed to close write pipe after start: %w", err)
+	}
+
+	// wait for the logging binary to be ready
+	b := make([]byte, 1)
+	if _, err := r.Read(b); err != nil && err != io.EOF {
+		return nil, fmt.Errorf("failed to read from logging binary: %w", err)
+	}
+
+	return &binaryIO{
+		cmd: cmd,
+		out: out,
+		err: serr,
+	}, nil
+}
+
+// newBinaryCmd returns a Cmd to be used to start a logging binary.
+// The Cmd is generated from the provided uri, and the container ID and
+// namespace are appended to the Cmd environment.
+func newBinaryCmd(binaryURI *url.URL, id, ns string) *execabs.Cmd {
+	var args []string
+	for k, vs := range binaryURI.Query() {
+		args = append(args, k)
+		if len(vs) > 0 {
+			args = append(args, vs[0])
+		}
+	}
+
+	cmd := execabs.Command(binaryURI.Path, args...)
+
+	cmd.Env = append(cmd.Env,
+		"CONTAINER_ID="+id,
+		"CONTAINER_NAMESPACE="+ns,
+	)
+
+	return cmd
+}
+
+func (bi *binaryIO) Stdin() io.ReadCloser {
+	return nil
+}
+
+func (bi *binaryIO) Stdout() io.Writer {
+	return bi.out.w
+}
+
+func (bi *binaryIO) Stderr() io.Writer {
+	return bi.err.w
+}
+
+func (bi *binaryIO) Close() error {
+	var (
+		result *multierror.Error
+	)
+
+	for _, v := range []*pipe{bi.out, bi.err} {
+		if v != nil {
+			if err := v.Close(); err != nil {
+				result = multierror.Append(result, err)
+			}
+		}
+	}
+
+	if err := bi.cancel(); err != nil {
+		result = multierror.Append(result, err)
+	}
+
+	return result.ErrorOrNil()
+}
+
+func (bi *binaryIO) cancel() error {
+	if bi.cmd == nil || bi.cmd.Process == nil {
+		return nil
+	}
+
+	// Send SIGTERM first, so logger process has a chance to flush and exit properly
+	if err := bi.cmd.Process.Signal(syscall.SIGTERM); err != nil {
+		result := multierror.Append(fmt.Errorf("failed to send SIGTERM: %w", err))
+
+		shimLog.WithError(err).Warn("failed to send SIGTERM signal, killing logging shim")
+
+		if err := bi.cmd.Process.Kill(); err != nil {
+			result = multierror.Append(result, fmt.Errorf("failed to kill process after faulty SIGTERM: %w", err))
+		}
+
+		return result.ErrorOrNil()
+	}
+
+	done := make(chan error, 1)
+	go func() {
+		done <- bi.cmd.Wait()
+	}()
+
+	select {
+	case err := <-done:
+		return err
+	case <-time.After(binaryIOProcTermTimeout):
+		shimLog.Warn("failed to wait for shim logger process to exit, killing")
+
+		err := bi.cmd.Process.Kill()
+		if err != nil {
+			return fmt.Errorf("failed to kill shim logger process: %w", err)
+		}
+
+		return nil
+	}
+}
+
+func newPipe() (*pipe, error) {
+	r, w, err := os.Pipe()
+	if err != nil {
+		return nil, err
+	}
+	return &pipe{
+		r: r,
+		w: w,
+	}, nil
+}
+
+type pipe struct {
+	r *os.File
+	w *os.File
+}
+
+// https://github.com/containerd/containerd/blob/v1.6.6/vendor/github.com/containerd/go-runc/io.go#L71
+func (p *pipe) Close() error {
+	var result *multierror.Error
+
+	if err := p.w.Close(); err != nil {
+		result = multierror.Append(result, fmt.Errorf("failed to close write pipe: %w", err))
+	}
+
+	if err := p.r.Close(); err != nil {
+		result = multierror.Append(result, fmt.Errorf("failed to close read pipe: %w", err))
+	}
+
+	return multierror.Prefix(result.ErrorOrNil(), "pipe:")
+}

src/runtime/pkg/containerd-shim-v2/shim_io_file.go

@@ -0,0 +1,80 @@
+// Copyright (c) 2022 Ant Group
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+package containerdshim
+
+import (
+	"context"
+	"io"
+	"net/url"
+	"os"
+	"path/filepath"
+
+	cioutil "github.com/containerd/containerd/pkg/ioutil"
+)
+
+var (
+	_ IO = &fileIO{}
+)
+
+// fileIO only support write both stdout/stderr to the same file
+type fileIO struct {
+	outw io.WriteCloser
+	errw io.WriteCloser
+	path string
+}
+
+// openLogFile opens/creates a container log file with its directory.
+func openLogFile(path string) (*os.File, error) {
+	if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
+		return nil, err
+	}
+	return os.OpenFile(path, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0640)
+}
+
+func newFileIO(ctx context.Context, stdio *stdio, uri *url.URL) (*fileIO, error) {
+	var outw, errw, f io.WriteCloser
+	var err error
+
+	logFile := uri.Path
+	if f, err = openLogFile(logFile); err != nil {
+		return nil, err
+	}
+
+	if stdio.Stdout != "" {
+		outw = cioutil.NewSerialWriteCloser(f)
+	}
+
+	if !stdio.Console && stdio.Stderr != "" {
+		errw = cioutil.NewSerialWriteCloser(f)
+	}
+
+	return &fileIO{
+		path: logFile,
+		outw: outw,
+		errw: errw,
+	}, nil
+}
+
+func (fi *fileIO) Close() error {
+	if fi.outw != nil {
+		return wc(fi.outw)
+	} else if fi.errw != nil {
+		return wc(fi.errw)
+	}
+	return nil
+}
+
+func (fi *fileIO) Stdin() io.ReadCloser {
+	return nil
+}
+
+func (fi *fileIO) Stdout() io.Writer {
+	return fi.outw
+}
+
+func (fi *fileIO) Stderr() io.Writer {
+	return fi.errw
+}

src/runtime/pkg/containerd-shim-v2/shim_io_pipe.go

@@ -0,0 +1,95 @@
+// Copyright (c) 2022 Ant Group
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+package containerdshim
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"syscall"
+
+	"github.com/containerd/fifo"
+	"github.com/hashicorp/go-multierror"
+)
+
+var (
+	_ IO = &pipeIO{}
+)
+
+type pipeIO struct {
+	in   io.ReadCloser
+	outw io.WriteCloser
+	errw io.WriteCloser
+}
+
+func newPipeIO(ctx context.Context, stdio *stdio) (*pipeIO, error) {
+	var in io.ReadCloser
+	var outw io.WriteCloser
+	var errw io.WriteCloser
+	var err error
+
+	if stdio.Stdin != "" {
+		in, err = fifo.OpenFifo(ctx, stdio.Stdin, syscall.O_RDONLY|syscall.O_NONBLOCK, 0)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	if stdio.Stdout != "" {
+		outw, err = fifo.OpenFifo(ctx, stdio.Stdout, syscall.O_RDWR, 0)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	if !stdio.Console && stdio.Stderr != "" {
+		errw, err = fifo.OpenFifo(ctx, stdio.Stderr, syscall.O_RDWR, 0)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	pipeIO := &pipeIO{
+		in:   in,
+		outw: outw,
+		errw: errw,
+	}
+
+	return pipeIO, nil
+}
+
+func (pi *pipeIO) Stdin() io.ReadCloser {
+	return pi.in
+}
+
+func (pi *pipeIO) Stdout() io.Writer {
+	return pi.outw
+}
+
+func (pi *pipeIO) Stderr() io.Writer {
+	return pi.errw
+}
+
+func (pi *pipeIO) Close() error {
+	var result *multierror.Error
+
+	if pi.in != nil {
+		if err := pi.in.Close(); err != nil {
+			result = multierror.Append(result, fmt.Errorf("failed to close stdin: %w", err))
+		}
+		pi.in = nil
+	}
+
+	if err := wc(pi.outw); err != nil {
+		result = multierror.Append(result, fmt.Errorf("failed to close stdout: %w", err))
+	}
+
+	if err := wc(pi.errw); err != nil {
+		result = multierror.Append(result, fmt.Errorf("failed to close stderr: %w", err))
+	}
+
+	return result.ErrorOrNil()
+}

src/runtime/pkg/containerd-shim-v2/start.go

@@ -8,6 +8,7 @@ package containerdshim
 import (
 	"context"
 	"fmt"
+
 	"github.com/sirupsen/logrus"
 
 	"github.com/containerd/containerd/api/types/task"
@@ -75,7 +76,7 @@ func startContainer(ctx context.Context, s *service, c *container) (retErr error
 	c.stdinPipe = stdin
 
 	if c.stdin != "" || c.stdout != "" || c.stderr != "" {
-		tty, err := newTtyIO(ctx, c.stdin, c.stdout, c.stderr, c.terminal)
+		tty, err := newTtyIO(ctx, s.namespace, c.id, c.stdin, c.stdout, c.stderr, c.terminal)
 		if err != nil {
 			return err
 		}
@@ -141,7 +142,7 @@ func startExec(ctx context.Context, s *service, containerID, execID string) (e *
 
 	execs.stdinPipe = stdin
 
-	tty, err := newTtyIO(ctx, execs.tty.stdin, execs.tty.stdout, execs.tty.stderr, execs.tty.terminal)
+	tty, err := newTtyIO(ctx, s.namespace, execs.id, execs.tty.stdin, execs.tty.stdout, execs.tty.stderr, execs.tty.terminal)
 	if err != nil {
 		return nil, err
 	}

src/runtime/pkg/containerd-shim-v2/stream.go

@@ -7,16 +7,22 @@ package containerdshim
 
 import (
 	"context"
+	"fmt"
 	"io"
+	"net/url"
 	"sync"
-	"syscall"
 
-	"github.com/containerd/fifo"
 	"github.com/sirupsen/logrus"
 )
 
-// The buffer size used to specify the buffer for IO streams copy
+const (
-const bufSize = 32 << 10
+	// The buffer size used to specify the buffer for IO streams copy
+	bufSize = 32 << 10
+
+	shimLogPluginBinary = "binary"
+	shimLogPluginFifo   = "fifo"
+	shimLogPluginFile   = "file"
+)
 
 var (
 	bufPool = sync.Pool{
@@ -27,76 +33,84 @@ var (
 	}
 )
 
+type stdio struct {
+	Stdin   string
+	Stdout  string
+	Stderr  string
+	Console bool
+}
+type IO interface {
+	io.Closer
+	Stdin() io.ReadCloser
+	Stdout() io.Writer
+	Stderr() io.Writer
+}
+
 type ttyIO struct {
-	Stdin  io.ReadCloser
+	io  IO
-	Stdout io.Writer
+	raw *stdio
-	Stderr io.Writer
 }
 
 func (tty *ttyIO) close() {
-
+	tty.io.Close()
-	if tty.Stdin != nil {
-		tty.Stdin.Close()
-		tty.Stdin = nil
-	}
-	cf := func(w io.Writer) {
-		if w == nil {
-			return
-		}
-		if c, ok := w.(io.WriteCloser); ok {
-			c.Close()
-		}
-	}
-	cf(tty.Stdout)
-	cf(tty.Stderr)
 }
 
-func newTtyIO(ctx context.Context, stdin, stdout, stderr string, console bool) (*ttyIO, error) {
+// newTtyIO creates a new ttyIO struct.
-	var in io.ReadCloser
+// ns(namespace)/id(container ID) are used for containerd binary IO.
-	var outw io.Writer
+// containerd will pass the ns/id as ENV to the binary log driver,
-	var errw io.Writer
+// and the binary log driver will use ns/id to get the log options config file.
+// for example nerdctl: https://github.com/containerd/nerdctl/blob/v0.21.0/pkg/logging/logging.go#L102
+func newTtyIO(ctx context.Context, ns, id, stdin, stdout, stderr string, console bool) (*ttyIO, error) {
 	var err error
+	var io IO
 
-	if stdin != "" {
+	raw := &stdio{
-		in, err = fifo.OpenFifo(ctx, stdin, syscall.O_RDONLY|syscall.O_NONBLOCK, 0)
+		Stdin:   stdin,
+		Stdout:  stdout,
+		Stderr:  stderr,
+		Console: console,
+	}
+
+	uri, err := url.Parse(stdout)
 	if err != nil {
-			return nil, err
+		return nil, fmt.Errorf("unable to parse stdout uri: %w", err)
-		}
+	}
+
+	if uri.Scheme == "" {
+		uri.Scheme = "fifo"
+	}
+
+	switch uri.Scheme {
+	case shimLogPluginFifo:
+		io, err = newPipeIO(ctx, raw)
+	case shimLogPluginBinary:
+		io, err = newBinaryIO(ctx, ns, id, uri)
+	case shimLogPluginFile:
+		io, err = newFileIO(ctx, raw, uri)
+	default:
+		return nil, fmt.Errorf("unknown STDIO scheme %s", uri.Scheme)
 	}
 
-	if stdout != "" {
-		outw, err = fifo.OpenFifo(ctx, stdout, syscall.O_RDWR, 0)
 	if err != nil {
-			return nil, err
+		return nil, fmt.Errorf("failed to creat io stream: %w", err)
-		}
 	}
 
-	if !console && stderr != "" {
+	return &ttyIO{
-		errw, err = fifo.OpenFifo(ctx, stderr, syscall.O_RDWR, 0)
+		io:  io,
-		if err != nil {
+		raw: raw,
-			return nil, err
+	}, nil
-		}
-	}
-
-	ttyIO := &ttyIO{
-		Stdin:  in,
-		Stdout: outw,
-		Stderr: errw,
-	}
-
-	return ttyIO, nil
 }
 
 func ioCopy(shimLog *logrus.Entry, exitch, stdinCloser chan struct{}, tty *ttyIO, stdinPipe io.WriteCloser, stdoutPipe, stderrPipe io.Reader) {
 	var wg sync.WaitGroup
 
-	if tty.Stdin != nil {
+	if tty.io.Stdin() != nil {
 		wg.Add(1)
 		go func() {
 			shimLog.Debug("stdin io stream copy started")
 			p := bufPool.Get().(*[]byte)
 			defer bufPool.Put(p)
-			io.CopyBuffer(stdinPipe, tty.Stdin, *p)
+			io.CopyBuffer(stdinPipe, tty.io.Stdin(), *p)
 			// notify that we can close process's io safely.
 			close(stdinCloser)
 			wg.Done()
@@ -104,30 +118,30 @@ func ioCopy(shimLog *logrus.Entry, exitch, stdinCloser chan struct{}, tty *ttyIO
 		}()
 	}
 
-	if tty.Stdout != nil {
+	if tty.io.Stdout() != nil {
 		wg.Add(1)
 
 		go func() {
 			shimLog.Debug("stdout io stream copy started")
 			p := bufPool.Get().(*[]byte)
 			defer bufPool.Put(p)
-			io.CopyBuffer(tty.Stdout, stdoutPipe, *p)
+			io.CopyBuffer(tty.io.Stdout(), stdoutPipe, *p)
 			wg.Done()
-			if tty.Stdin != nil {
+			if tty.io.Stdin() != nil {
 				// close stdin to make the other routine stop
-				tty.Stdin.Close()
+				tty.io.Stdin().Close()
 			}
 			shimLog.Debug("stdout io stream copy exited")
 		}()
 	}
 
-	if tty.Stderr != nil && stderrPipe != nil {
+	if tty.io.Stderr() != nil && stderrPipe != nil {
 		wg.Add(1)
 		go func() {
 			shimLog.Debug("stderr io stream copy started")
 			p := bufPool.Get().(*[]byte)
 			defer bufPool.Put(p)
-			io.CopyBuffer(tty.Stderr, stderrPipe, *p)
+			io.CopyBuffer(tty.io.Stderr(), stderrPipe, *p)
 			wg.Done()
 			shimLog.Debug("stderr io stream copy exited")
 		}()
@@ -138,3 +152,10 @@ func ioCopy(shimLog *logrus.Entry, exitch, stdinCloser chan struct{}, tty *ttyIO
 	close(exitch)
 	shimLog.Debug("all io stream copy goroutines exited")
 }
+
+func wc(w io.WriteCloser) error {
+	if w == nil {
+		return nil
+	}
+	return w.Close()
+}

src/runtime/pkg/containerd-shim-v2/stream_test.go

@@ -7,7 +7,6 @@ package containerdshim
 
 import (
 	"context"
-	"github.com/sirupsen/logrus"
 	"io"
 	"os"
 	"path/filepath"
@@ -15,6 +14,8 @@ import (
 	"testing"
 	"time"
 
+	"github.com/sirupsen/logrus"
+
 	"github.com/containerd/fifo"
 	"github.com/stretchr/testify/assert"
 )
@@ -45,7 +46,7 @@ func TestNewTtyIOFifoReopen(t *testing.T) {
 	defer outr.Close()
 	errr = createReadFifo(stderr)
 	defer errr.Close()
-	tty, err = newTtyIO(ctx, "", stdout, stderr, false)
+	tty, err = newTtyIO(ctx, "", "", "", stdout, stderr, false)
 	assert.NoError(err)
 	defer tty.close()
 
@@ -72,9 +73,9 @@ func TestNewTtyIOFifoReopen(t *testing.T) {
 		}
 	}
 
-	checkFifoWrite(tty.Stdout)
+	checkFifoWrite(tty.io.Stdout())
 	checkFifoRead(outr)
-	checkFifoWrite(tty.Stderr)
+	checkFifoWrite(tty.io.Stderr())
 	checkFifoRead(errr)
 
 	err = outr.Close()
@@ -84,8 +85,8 @@ func TestNewTtyIOFifoReopen(t *testing.T) {
 
 	// Make sure that writing to tty fifo will not get `EPIPE`
 	// when the read side is closed
-	checkFifoWrite(tty.Stdout)
+	checkFifoWrite(tty.io.Stdout())
-	checkFifoWrite(tty.Stderr)
+	checkFifoWrite(tty.io.Stderr())
 
 	// Reopen the fifo
 	outr = createReadFifo(stdout)
@@ -171,7 +172,7 @@ func TestIoCopy(t *testing.T) {
 			defer srcInW.Close()
 		}
 
-		tty, err := newTtyIO(ctx, srcStdinPath, dstStdoutPath, dstStderrPath, false)
+		tty, err := newTtyIO(ctx, "", "", srcStdinPath, dstStdoutPath, dstStderrPath, false)
 		assert.NoError(err)
 		defer tty.close()
 

src/runtime/vendor/github.com/containerd/containerd/pkg/ioutil/read_closer.go

@@ -0,0 +1,57 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package ioutil
+
+import "io"
+
+// writeCloseInformer wraps a reader with a close function.
+type wrapReadCloser struct {
+	reader *io.PipeReader
+	writer *io.PipeWriter
+}
+
+// NewWrapReadCloser creates a wrapReadCloser from a reader.
+// NOTE(random-liu): To avoid goroutine leakage, the reader passed in
+// must be eventually closed by the caller.
+func NewWrapReadCloser(r io.Reader) io.ReadCloser {
+	pr, pw := io.Pipe()
+	go func() {
+		_, _ = io.Copy(pw, r)
+		pr.Close()
+		pw.Close()
+	}()
+	return &wrapReadCloser{
+		reader: pr,
+		writer: pw,
+	}
+}
+
+// Read reads up to len(p) bytes into p.
+func (w *wrapReadCloser) Read(p []byte) (int, error) {
+	n, err := w.reader.Read(p)
+	if err == io.ErrClosedPipe {
+		return n, io.EOF
+	}
+	return n, err
+}
+
+// Close closes read closer.
+func (w *wrapReadCloser) Close() error {
+	w.reader.Close()
+	w.writer.Close()
+	return nil
+}

src/runtime/vendor/github.com/containerd/containerd/pkg/ioutil/write_closer.go

@@ -0,0 +1,102 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package ioutil
+
+import (
+	"io"
+	"sync"
+)
+
+// writeCloseInformer wraps passed in write closer with a close channel.
+// Caller could wait on the close channel for the write closer to be
+// closed.
+type writeCloseInformer struct {
+	close chan struct{}
+	wc    io.WriteCloser
+}
+
+// NewWriteCloseInformer creates the writeCloseInformer from a write closer.
+func NewWriteCloseInformer(wc io.WriteCloser) (io.WriteCloser, <-chan struct{}) {
+	close := make(chan struct{})
+	return &writeCloseInformer{
+		close: close,
+		wc:    wc,
+	}, close
+}
+
+// Write passes through the data into the internal write closer.
+func (w *writeCloseInformer) Write(p []byte) (int, error) {
+	return w.wc.Write(p)
+}
+
+// Close closes the internal write closer and inform the close channel.
+func (w *writeCloseInformer) Close() error {
+	err := w.wc.Close()
+	close(w.close)
+	return err
+}
+
+// nopWriteCloser wraps passed in writer with a nop close function.
+type nopWriteCloser struct {
+	w io.Writer
+}
+
+// NewNopWriteCloser creates the nopWriteCloser from a writer.
+func NewNopWriteCloser(w io.Writer) io.WriteCloser {
+	return &nopWriteCloser{w: w}
+}
+
+// Write passes through the data into the internal writer.
+func (n *nopWriteCloser) Write(p []byte) (int, error) {
+	return n.w.Write(p)
+}
+
+// Close is a nop close function.
+func (n *nopWriteCloser) Close() error {
+	return nil
+}
+
+// serialWriteCloser wraps a write closer and makes sure all writes
+// are done in serial.
+// Parallel write won't intersect with each other. Use case:
+// 1) Pipe: Write content longer than PIPE_BUF.
+//    See http://man7.org/linux/man-pages/man7/pipe.7.html
+// 2) <3.14 Linux Kernel: write is not atomic
+//    See http://man7.org/linux/man-pages/man2/write.2.html
+type serialWriteCloser struct {
+	mu sync.Mutex
+	wc io.WriteCloser
+}
+
+// NewSerialWriteCloser creates a SerialWriteCloser from a write closer.
+func NewSerialWriteCloser(wc io.WriteCloser) io.WriteCloser {
+	return &serialWriteCloser{wc: wc}
+}
+
+// Write writes a group of byte arrays in order atomically.
+func (s *serialWriteCloser) Write(data []byte) (int, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.wc.Write(data)
+}
+
+// Close closes the write closer.
+func (s *serialWriteCloser) Close() error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.wc.Close()
+}

src/runtime/vendor/github.com/containerd/containerd/pkg/ioutil/writer_group.go

@@ -0,0 +1,105 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package ioutil
+
+import (
+	"errors"
+	"io"
+	"sync"
+)
+
+// WriterGroup is a group of writers. Writer could be dynamically
+// added and removed.
+type WriterGroup struct {
+	mu      sync.Mutex
+	writers map[string]io.WriteCloser
+	closed  bool
+}
+
+var _ io.Writer = &WriterGroup{}
+
+// NewWriterGroup creates an empty writer group.
+func NewWriterGroup() *WriterGroup {
+	return &WriterGroup{
+		writers: make(map[string]io.WriteCloser),
+	}
+}
+
+// Add adds a writer into the group. The writer will be closed
+// if the writer group is closed.
+func (g *WriterGroup) Add(key string, w io.WriteCloser) {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	if g.closed {
+		w.Close()
+		return
+	}
+	g.writers[key] = w
+}
+
+// Get gets a writer from the group, returns nil if the writer
+// doesn't exist.
+func (g *WriterGroup) Get(key string) io.WriteCloser {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	return g.writers[key]
+}
+
+// Remove removes a writer from the group.
+func (g *WriterGroup) Remove(key string) {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	w, ok := g.writers[key]
+	if !ok {
+		return
+	}
+	w.Close()
+	delete(g.writers, key)
+}
+
+// Write writes data into each writer. If a writer returns error,
+// it will be closed and removed from the writer group. It returns
+// error if writer group is empty.
+func (g *WriterGroup) Write(p []byte) (int, error) {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	for k, w := range g.writers {
+		n, err := w.Write(p)
+		if err == nil && len(p) == n {
+			continue
+		}
+		// The writer is closed or in bad state, remove it.
+		w.Close()
+		delete(g.writers, k)
+	}
+	if len(g.writers) == 0 {
+		return 0, errors.New("writer group is empty")
+	}
+	return len(p), nil
+}
+
+// Close closes the writer group. Write will return error after
+// closed.
+func (g *WriterGroup) Close() {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	for _, w := range g.writers {
+		w.Close()
+	}
+	g.writers = nil
+	g.closed = true
+}

src/runtime/vendor/modules.txt

@@ -79,6 +79,7 @@ github.com/containerd/containerd/mount
 github.com/containerd/containerd/namespaces
 github.com/containerd/containerd/pkg/cri/annotations
 github.com/containerd/containerd/pkg/dialer
+github.com/containerd/containerd/pkg/ioutil
 github.com/containerd/containerd/pkg/runtimeoptions/v1
 github.com/containerd/containerd/pkg/shutdown
 github.com/containerd/containerd/pkg/ttrpcutil