exec.go

/*
   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 tasks

import (
	"errors"
	"io"
	"net/url"
	"os"

	"github.com/containerd/console"
	"github.com/containerd/containerd"
	"github.com/containerd/containerd/cio"
	"github.com/containerd/containerd/cmd/ctr/commands"
	"github.com/sirupsen/logrus"
	"github.com/urfave/cli"
)

//TODO:(jessvalarezo) exec-id is optional here, update to required arg
var execCommand = cli.Command{
	Name:           "exec",
	Usage:          "execute additional processes in an existing container",
	ArgsUsage:      "[flags] CONTAINER CMD [ARG...]",
	SkipArgReorder: true,
	Flags: []cli.Flag{
		cli.StringFlag{
			Name:  "cwd",
			Usage: "working directory of the new process",
		},
		cli.BoolFlag{
			Name:  "tty,t",
			Usage: "allocate a TTY for the container",
		},
		cli.BoolFlag{
			Name:  "detach,d",
			Usage: "detach from the task after it has started execution",
		},
		cli.StringFlag{
			Name:  "exec-id",
			Usage: "exec specific id for the process",
		},
		cli.StringFlag{
			Name:  "fifo-dir",
			Usage: "directory used for storing IO FIFOs",
		},
		cli.StringFlag{
			Name:  "log-uri",
			Usage: "log uri for custom shim logging",
		},
	},
	Action: func(context *cli.Context) error {
		var (
			id     = context.Args().First()
			args   = context.Args().Tail()
			tty    = context.Bool("tty")
			detach = context.Bool("detach")
		)
		if id == "" {
			return errors.New("container id must be provided")
		}
		client, ctx, cancel, err := commands.NewClient(context)
		if err != nil {
			return err
		}
		defer cancel()
		container, err := client.LoadContainer(ctx, id)
		if err != nil {
			return err
		}
		spec, err := container.Spec(ctx)
		if err != nil {
			return err
		}
		task, err := container.Task(ctx, nil)
		if err != nil {
			return err
		}

		pspec := spec.Process
		pspec.Terminal = tty
		pspec.Args = args

		var (
			ioCreator cio.Creator
			stdinC    = &stdinCloser{
				stdin: os.Stdin,
			}
		)

		if logURI := context.String("log-uri"); logURI != "" {
			uri, err := url.Parse(logURI)
			if err != nil {
				return err
			}

			if dir := context.String("fifo-dir"); dir != "" {
				return errors.New("can't use log-uri with fifo-dir")
			}

			if tty {
				return errors.New("can't use log-uri with tty")
			}

			ioCreator = cio.LogURI(uri)
		} else {
			cioOpts := []cio.Opt{cio.WithStreams(stdinC, os.Stdout, os.Stderr), cio.WithFIFODir(context.String("fifo-dir"))}
			if tty {
				cioOpts = append(cioOpts, cio.WithTerminal)
			}
			ioCreator = cio.NewCreator(cioOpts...)
		}

		process, err := task.Exec(ctx, context.String("exec-id"), pspec, ioCreator)
		if err != nil {
			return err
		}
		stdinC.closer = func() {
			process.CloseIO(ctx, containerd.WithStdinCloser)
		}
		// if detach, we should not call this defer
		if !detach {
			defer process.Delete(ctx)
		}

		statusC, err := process.Wait(ctx)
		if err != nil {
			return err
		}

		var con console.Console
		if tty {
			con = console.Current()
			defer con.Reset()
			if err := con.SetRaw(); err != nil {
				return err
			}
		}
		if !detach {
			if tty {
				if err := HandleConsoleResize(ctx, process, con); err != nil {
					logrus.WithError(err).Error("console resize")
				}
			} else {
				sigc := commands.ForwardAllSignals(ctx, process)
				defer commands.StopCatch(sigc)
			}
		}

		if err := process.Start(ctx); err != nil {
			return err
		}
		if detach {
			return nil
		}
		status := <-statusC
		code, _, err := status.Result()
		if err != nil {
			return err
		}
		if code != 0 {
			return cli.NewExitError("", int(code))
		}
		return nil
	},
}

type stdinCloser struct {
	stdin  *os.File
	closer func()
}

func (s *stdinCloser) Read(p []byte) (int, error) {
	n, err := s.stdin.Read(p)
	if err == io.EOF {
		if s.closer != nil {
			s.closer()
		}
	}
	return n, err
}