cmd/ctr/commands/tasks/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"
	containerd "github.com/containerd/containerd/v2/client"
	"github.com/containerd/containerd/v2/cmd/ctr/commands"
	"github.com/containerd/containerd/v2/pkg/cio"
	"github.com/containerd/containerd/v2/pkg/oci"
	"github.com/containerd/log"
	"github.com/urfave/cli/v2"
)

var execCommand = &cli.Command{
	Name:      "exec",
	Usage:     "Execute additional processes in an existing container",
	ArgsUsage: "[flags] CONTAINER CMD [ARG...]",
	Flags: []cli.Flag{
		&cli.StringFlag{
			Name:  "cwd",
			Usage: "Working directory of the new process",
		},
		&cli.BoolFlag{
			Name:    "tty",
			Aliases: []string{"t"},
			Usage:   "Allocate a TTY for the container",
		},
		&cli.BoolFlag{
			Name:    "detach",
			Aliases: []string{"d"},
			Usage:   "Detach from the task after it has started execution",
		},
		&cli.StringFlag{
			Name:     "exec-id",
			Required: true,
			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",
		},
		&cli.StringFlag{
			Name:  "user",
			Usage: "User id or name",
		},
	},
	Action: func(cliContext *cli.Context) error {
		var (
			id     = cliContext.Args().First()
			args   = cliContext.Args().Tail()
			tty    = cliContext.Bool("tty")
			detach = cliContext.Bool("detach")
		)
		if id == "" {
			return errors.New("container id must be provided")
		}
		client, ctx, cancel, err := commands.NewClient(cliContext)
		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
		}
		if user := cliContext.String("user"); user != "" {
			c, err := container.Info(ctx)
			if err != nil {
				return err
			}
			if err := oci.WithUser(user)(ctx, client, &c, spec); err != nil {
				return err
			}
		}

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

		if cwd := cliContext.String("cwd"); cwd != "" {
			pspec.Cwd = cwd
		}

		task, err := container.Task(ctx, nil)
		if err != nil {
			return err
		}

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

		fifoDir := cliContext.String("fifo-dir")
		logURI := cliContext.String("log-uri")
		ioOpts := []cio.Opt{cio.WithFIFODir(fifoDir)}
		switch {
		case tty && logURI != "":
			return errors.New("can't use log-uri with tty")
		case logURI != "" && fifoDir != "":
			return errors.New("can't use log-uri with fifo-dir")

		case tty:
			con = console.Current()
			defer con.Reset()
			if err := con.SetRaw(); err != nil {
				return err
			}
			ioCreator = cio.NewCreator(append([]cio.Opt{cio.WithStreams(con, con, nil), cio.WithTerminal}, ioOpts...)...)

		case logURI != "":
			uri, err := url.Parse(logURI)
			if err != nil {
				return err
			}
			ioCreator = cio.LogURI(uri)

		default:
			ioCreator = cio.NewCreator(append([]cio.Opt{cio.WithStreams(stdinC, os.Stdout, os.Stderr)}, ioOpts...)...)
		}

		process, err := task.Exec(ctx, cliContext.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
		}

		if err := process.Start(ctx); err != nil {
			return err
		}
		if detach {
			return nil
		}
		if tty {
			if err := HandleConsoleResize(ctx, process, con); err != nil {
				log.L.WithError(err).Error("console resize")
			}
		} else {
			sigc := commands.ForwardAllSignals(ctx, process)
			defer commands.StopCatch(sigc)
		}
		status := <-statusC
		code, _, err := status.Result()
		if err != nil {
			return err
		}
		if code != 0 {
			return cli.Exit("", 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
}