Merge pull request #2672 from amscanne:shim-integrated

PiperOrigin-RevId: 321053634

1 files changed, 265 insertions, 0 deletions

diff --git a/shim/v1/main.go b/shim/v1/main.go
new file mode 100644
index 000000000..3159923af
--- /dev/null
+++ b/shim/v1/main.go
@@ -0,0 +1,265 @@
+// Copyright 2018 The containerd Authors.
+// Copyright 2019 The gVisor 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
+//
+//     https://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 main
+
+import (
+	"bytes"
+	"context"
+	"flag"
+	"fmt"
+	"log"
+	"net"
+	"os"
+	"os/exec"
+	"os/signal"
+	"path/filepath"
+	"strings"
+	"sync"
+	"syscall"
+
+	"github.com/containerd/containerd/events"
+	"github.com/containerd/containerd/namespaces"
+	"github.com/containerd/containerd/sys"
+	"github.com/containerd/containerd/sys/reaper"
+	"github.com/containerd/ttrpc"
+	"github.com/containerd/typeurl"
+	"github.com/gogo/protobuf/types"
+	"golang.org/x/sys/unix"
+
+	"gvisor.dev/gvisor/pkg/shim/runsc"
+	"gvisor.dev/gvisor/pkg/shim/v1/shim"
+)
+
+var (
+	debugFlag            bool
+	namespaceFlag        string
+	socketFlag           string
+	addressFlag          string
+	workdirFlag          string
+	runtimeRootFlag      string
+	containerdBinaryFlag string
+	shimConfigFlag       string
+)
+
+// Containerd defaults to runc, unless another runtime is explicitly specified.
+// We keep the same default to make the default behavior consistent.
+const defaultRoot = "/run/containerd/runc"
+
+func init() {
+	flag.BoolVar(&debugFlag, "debug", false, "enable debug output in logs")
+	flag.StringVar(&namespaceFlag, "namespace", "", "namespace that owns the shim")
+	flag.StringVar(&socketFlag, "socket", "", "abstract socket path to serve")
+	flag.StringVar(&addressFlag, "address", "", "grpc address back to main containerd")
+	flag.StringVar(&workdirFlag, "workdir", "", "path used to storge large temporary data")
+	flag.StringVar(&runtimeRootFlag, "runtime-root", defaultRoot, "root directory for the runtime")
+
+	// Currently, the `containerd publish` utility is embedded in the
+	// daemon binary.  The daemon invokes `containerd-shim
+	// -containerd-binary ...` with its own os.Executable() path.
+	flag.StringVar(&containerdBinaryFlag, "containerd-binary", "containerd", "path to containerd binary (used for `containerd publish`)")
+	flag.StringVar(&shimConfigFlag, "config", "/etc/containerd/runsc.toml", "path to the shim configuration file")
+}
+
+func main() {
+	flag.Parse()
+
+	// This is a hack. Exec current process to run standard containerd-shim
+	// if runtime root is not `runsc`. We don't need this for shim v2 api.
+	if filepath.Base(runtimeRootFlag) != "runsc" {
+		if err := executeRuncShim(); err != nil {
+			fmt.Fprintf(os.Stderr, "gvisor-containerd-shim: %s\n", err)
+			os.Exit(1)
+		}
+	}
+
+	// Run regular shim if needed.
+	if err := executeShim(); err != nil {
+		fmt.Fprintf(os.Stderr, "gvisor-containerd-shim: %s\n", err)
+		os.Exit(1)
+	}
+}
+
+// executeRuncShim execs current process to a containerd-shim process and
+// retains all flags and envs.
+func executeRuncShim() error {
+	c, err := loadConfig(shimConfigFlag)
+	if err != nil && !os.IsNotExist(err) {
+		return fmt.Errorf("failed to load shim config: %w", err)
+	}
+	shimPath := c.RuncShim
+	if shimPath == "" {
+		shimPath, err = exec.LookPath("containerd-shim")
+		if err != nil {
+			return fmt.Errorf("lookup containerd-shim failed: %w", err)
+		}
+	}
+
+	args := append([]string{shimPath}, os.Args[1:]...)
+	if err := syscall.Exec(shimPath, args, os.Environ()); err != nil {
+		return fmt.Errorf("exec containerd-shim @ %q failed: %w", shimPath, err)
+	}
+	return nil
+}
+
+func executeShim() error {
+	// start handling signals as soon as possible so that things are
+	// properly reaped or if runtime exits before we hit the handler.
+	signals, err := setupSignals()
+	if err != nil {
+		return err
+	}
+	path, err := os.Getwd()
+	if err != nil {
+		return err
+	}
+	server, err := ttrpc.NewServer(ttrpc.WithServerHandshaker(ttrpc.UnixSocketRequireSameUser()))
+	if err != nil {
+		return fmt.Errorf("failed creating server: %w", err)
+	}
+	c, err := loadConfig(shimConfigFlag)
+	if err != nil && !os.IsNotExist(err) {
+		return fmt.Errorf("failed to load shim config: %w", err)
+	}
+	sv, err := shim.NewService(
+		shim.Config{
+			Path:        path,
+			Namespace:   namespaceFlag,
+			WorkDir:     workdirFlag,
+			RuntimeRoot: runtimeRootFlag,
+			RunscConfig: c.RunscConfig,
+		},
+		&remoteEventsPublisher{address: addressFlag},
+	)
+	if err != nil {
+		return err
+	}
+	registerShimService(server, sv)
+	if err := serve(server, socketFlag); err != nil {
+		return err
+	}
+	return handleSignals(signals, server, sv)
+}
+
+// serve serves the ttrpc API over a unix socket at the provided path this
+// function does not block.
+func serve(server *ttrpc.Server, path string) error {
+	var (
+		l   net.Listener
+		err error
+	)
+	if path == "" {
+		l, err = net.FileListener(os.NewFile(3, "socket"))
+		path = "[inherited from parent]"
+	} else {
+		if len(path) > 106 {
+			return fmt.Errorf("%q: unix socket path too long (> 106)", path)
+		}
+		l, err = net.Listen("unix", "\x00"+path)
+	}
+	if err != nil {
+		return err
+	}
+	go func() {
+		defer l.Close()
+		err := server.Serve(context.Background(), l)
+		if err != nil && !strings.Contains(err.Error(), "use of closed network connection") {
+			log.Fatalf("ttrpc server failure: %v", err)
+		}
+	}()
+	return nil
+}
+
+// setupSignals creates a new signal handler for all signals and sets the shim
+// as a sub-reaper so that the container processes are reparented.
+func setupSignals() (chan os.Signal, error) {
+	signals := make(chan os.Signal, 32)
+	signal.Notify(signals, unix.SIGTERM, unix.SIGINT, unix.SIGCHLD, unix.SIGPIPE)
+	// make sure runc is setup to use the monitor for waiting on processes.
+	// TODO(random-liu): Move shim/reaper.go to a separate package.
+	runsc.Monitor = reaper.Default
+	// Set the shim as the subreaper for all orphaned processes created by
+	// the container.
+	if err := unix.Prctl(unix.PR_SET_CHILD_SUBREAPER, 1, 0, 0, 0); err != nil {
+		return nil, err
+	}
+	return signals, nil
+}
+
+func handleSignals(signals chan os.Signal, server *ttrpc.Server, sv *shim.Service) error {
+	var (
+		termOnce sync.Once
+		done     = make(chan struct{})
+	)
+
+	for {
+		select {
+		case <-done:
+			return nil
+		case s := <-signals:
+			switch s {
+			case unix.SIGCHLD:
+				if _, err := sys.Reap(false); err != nil {
+					log.Printf("reap error: %v", err)
+				}
+			case unix.SIGTERM, unix.SIGINT:
+				go termOnce.Do(func() {
+					ctx := context.TODO()
+					if err := server.Shutdown(ctx); err != nil {
+						log.Printf("failed to shutdown server: %v", err)
+					}
+					// Ensure our child is dead if any.
+					sv.Kill(ctx, &KillRequest{
+						Signal: uint32(syscall.SIGKILL),
+						All:    true,
+					})
+					sv.Delete(context.Background(), &types.Empty{})
+					close(done)
+				})
+			case unix.SIGPIPE:
+			}
+		}
+	}
+}
+
+type remoteEventsPublisher struct {
+	address string
+}
+
+func (l *remoteEventsPublisher) Publish(ctx context.Context, topic string, event events.Event) error {
+	ns, _ := namespaces.Namespace(ctx)
+	encoded, err := typeurl.MarshalAny(event)
+	if err != nil {
+		return err
+	}
+	data, err := encoded.Marshal()
+	if err != nil {
+		return err
+	}
+	cmd := exec.CommandContext(ctx, containerdBinaryFlag, "--address", l.address, "publish", "--topic", topic, "--namespace", ns)
+	cmd.Stdin = bytes.NewReader(data)
+	c, err := reaper.Default.Start(cmd)
+	if err != nil {
+		return err
+	}
+	status, err := reaper.Default.Wait(cmd, c)
+	if err != nil {
+		return fmt.Errorf("failed to publish event: %w", err)
+	}
+	if status != 0 {
+		return fmt.Errorf("failed to publish event: status %d", status)
+	}
+	return nil
+}