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Implement non-terminal attach

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We use a SOCK_SEQPACKET socket for the attach unix domain socket, which
means the kernel will ensure that the reading side only ever get the
data from one write operation. We use this for frameing, where the
first byte is the pipe that the next bytes are for. We have to make sure
that all reads from the socket are using at least the same size of buffer
as the write side, because otherwise the extra data in the message
will be dropped.

This also adds a stdin pipe for the container, similar to the ones we
use for stdout/err, because we need a way for an attached client
to write to stdin, even if not using a tty.

This fixes https://github.com/kubernetes-incubator/cri-o/issues/569

Signed-off-by: Alexander Larsson <alexl@redhat.com>
This commit is contained in:
Alexander Larsson 2017-06-08 22:08:29 +02:00
parent e3170caa2e
commit 7bb957bf75
8 changed files with 143 additions and 42 deletions
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60
server/container_attach.go
View file

@ -3,14 +3,12 @@ package server
import (
"fmt"
"io"
"io/ioutil"
"net"
"os"
"path/filepath"
"syscall"
"github.com/Sirupsen/logrus"
"github.com/docker/docker/pkg/pools"
"github.com/kubernetes-incubator/cri-o/oci"
"github.com/kubernetes-incubator/cri-o/utils"
"golang.org/x/net/context"
@ -19,6 +17,13 @@ import (
"k8s.io/kubernetes/pkg/util/term"
)
/* Sync with stdpipe_t in conmon.c */
const (
AttachPipeStdin = 1
AttachPipeStdout = 2
AttachPipeStderr = 3
)
// Attach prepares a streaming endpoint to attach to a running container.
func (s *Server) Attach(ctx context.Context, req *pb.AttachRequest) (*pb.AttachResponse, error) {
logrus.Debugf("AttachRequest %+v", req)
@ -63,7 +68,7 @@ func (ss streamService) Attach(containerID string, inputStream io.Reader, output
})
attachSocketPath := filepath.Join("/var/run/crio", c.ID(), "attach")
conn, err := net.Dial("unix", attachSocketPath)
conn, err := net.DialUnix("unixpacket", nil, &net.UnixAddr{Name: attachSocketPath, Net: "unixpacket"})
if err != nil {
return fmt.Errorf("failed to connect to container %s attach socket: %v", c.ID(), err)
}
@ -72,7 +77,7 @@ func (ss streamService) Attach(containerID string, inputStream io.Reader, output
receiveStdout := make(chan error)
if outputStream != nil || errorStream != nil {
go func() {
receiveStdout <- redirectResponseToOutputStream(tty, outputStream, errorStream, conn)
receiveStdout <- redirectResponseToOutputStreams(outputStream, errorStream, conn)
}()
}
@ -81,6 +86,7 @@ func (ss streamService) Attach(containerID string, inputStream io.Reader, output
var err error
if inputStream != nil {
_, err = utils.CopyDetachable(conn, inputStream, nil)
conn.CloseWrite()
}
stdinDone <- err
}()
@ -100,18 +106,42 @@ func (ss streamService) Attach(containerID string, inputStream io.Reader, output
return nil
}
func redirectResponseToOutputStream(tty bool, outputStream, errorStream io.Writer, conn io.Reader) error {
if outputStream == nil {
outputStream = ioutil.Discard
}
if errorStream == nil {
// errorStream = ioutil.Discard
}
func redirectResponseToOutputStreams(outputStream, errorStream io.Writer, conn io.Reader) error {
var err error
if tty {
_, err = pools.Copy(outputStream, conn)
} else {
// TODO
buf := make([]byte, 8192+1) /* Sync with conmon STDIO_BUF_SIZE */
for {
nr, er := conn.Read(buf)
if nr > 0 {
var dst io.Writer
if buf[0] == AttachPipeStdout {
dst = outputStream
} else if buf[0] == AttachPipeStderr {
dst = errorStream
} else {
logrus.Infof("Got unexpected attach type %+d", buf[0])
}
if dst != nil {
nw, ew := dst.Write(buf[1:nr])
if ew != nil {
err = ew
break
}
if nr != nw+1 {
err = io.ErrShortWrite
break
}
}
}
if er == io.EOF {
break
}
if er != nil {
err = er
break
}
}
return err
}