containerd/linux/shim/service_linux.go
Daniel Dao 8e53465842
use epoll to manage console i/o in linux
this adds a `platform` interface for shim service to manage platform-specific
behaviors such as I/O (which uses epoll in linux to work around bugs with applications
that closes all consoles i.e. https://github.com/opencontainers/runc/pull/1434
and https://github.com/moby/moby/issues/27202)

Its expected that we only have 1 epollfd per containerd_shim to manage all processes.
Since all the work are done outside of the container runtime, upgrading of runc
is not required and should be done separately.

Signed-off-by: Daniel Dao <dqminh89@gmail.com>
2017-07-30 10:50:39 +01:00

88 lines
1.8 KiB
Go

package shim
import (
"io"
"sync"
"syscall"
"github.com/containerd/console"
"github.com/containerd/fifo"
"github.com/pkg/errors"
"golang.org/x/net/context"
)
type linuxPlatform struct {
epoller *console.Epoller
}
func (p *linuxPlatform) copyConsole(ctx context.Context, console console.Console, stdin, stdout, stderr string, wg, cwg *sync.WaitGroup) (console.Console, error) {
if p.epoller == nil {
return nil, errors.New("uninitialized epoller")
}
epollConsole, err := p.epoller.Add(console)
if err != nil {
return nil, err
}
if stdin != "" {
in, err := fifo.OpenFifo(ctx, stdin, syscall.O_RDONLY, 0)
if err != nil {
return nil, err
}
cwg.Add(1)
go func() {
cwg.Done()
io.Copy(epollConsole, in)
}()
}
outw, err := fifo.OpenFifo(ctx, stdout, syscall.O_WRONLY, 0)
if err != nil {
return nil, err
}
outr, err := fifo.OpenFifo(ctx, stdout, syscall.O_RDONLY, 0)
if err != nil {
return nil, err
}
wg.Add(1)
cwg.Add(1)
go func() {
cwg.Done()
io.Copy(outw, epollConsole)
epollConsole.Close()
outr.Close()
outw.Close()
wg.Done()
}()
return epollConsole, nil
}
func (p *linuxPlatform) shutdownConsole(ctx context.Context, cons console.Console) error {
if p.epoller == nil {
return errors.New("uninitialized epoller")
}
epollConsole, ok := cons.(*console.EpollConsole)
if !ok {
return errors.Errorf("expected EpollConsole, got %#v", cons)
}
return epollConsole.Shutdown(p.epoller.CloseConsole)
}
// initialize a single epoll fd to manage our consoles. `initPlatform` should
// only be called once.
func (s *Service) initPlatform() error {
if s.platform != nil {
return nil
}
epoller, err := console.NewEpoller()
if err != nil {
return errors.Wrap(err, "failed to initialize epoller")
}
s.platform = &linuxPlatform{
epoller: epoller,
}
go epoller.Wait()
return nil
}