151 lines
4.2 KiB
Go
151 lines
4.2 KiB
Go
// Copyright 2018 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package cmd
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import (
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"context"
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"os"
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"path/filepath"
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"syscall"
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"flag"
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"github.com/google/subcommands"
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"gvisor.googlesource.com/gvisor/pkg/log"
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"gvisor.googlesource.com/gvisor/runsc/boot"
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"gvisor.googlesource.com/gvisor/runsc/container"
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"gvisor.googlesource.com/gvisor/runsc/specutils"
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)
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// File containing the container's saved image/state within the given image-path's directory.
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const checkpointFileName = "checkpoint.img"
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// Checkpoint implements subcommands.Command for the "checkpoint" command.
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type Checkpoint struct {
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imagePath string
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leaveRunning bool
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}
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// Name implements subcommands.Command.Name.
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func (*Checkpoint) Name() string {
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return "checkpoint"
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}
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// Synopsis implements subcommands.Command.Synopsis.
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func (*Checkpoint) Synopsis() string {
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return "checkpoint current state of container (experimental)"
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}
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// Usage implements subcommands.Command.Usage.
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func (*Checkpoint) Usage() string {
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return `checkpoint [flags] <container id> - save current state of container.
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`
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}
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// SetFlags implements subcommands.Command.SetFlags.
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func (c *Checkpoint) SetFlags(f *flag.FlagSet) {
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f.StringVar(&c.imagePath, "image-path", "", "directory path to saved container image")
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f.BoolVar(&c.leaveRunning, "leave-running", false, "restart the container after checkpointing")
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// Unimplemented flags necessary for compatibility with docker.
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var wp string
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f.StringVar(&wp, "work-path", "", "ignored")
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}
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// Execute implements subcommands.Command.Execute.
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func (c *Checkpoint) Execute(_ context.Context, f *flag.FlagSet, args ...interface{}) subcommands.ExitStatus {
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if f.NArg() != 1 {
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f.Usage()
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return subcommands.ExitUsageError
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}
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id := f.Arg(0)
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conf := args[0].(*boot.Config)
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waitStatus := args[1].(*syscall.WaitStatus)
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cont, err := container.Load(conf.RootDir, id)
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if err != nil {
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Fatalf("loading container: %v", err)
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}
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if c.imagePath == "" {
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Fatalf("image-path flag must be provided")
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}
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if err := os.MkdirAll(c.imagePath, 0755); err != nil {
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Fatalf("making directories at path provided: %v", err)
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}
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fullImagePath := filepath.Join(c.imagePath, checkpointFileName)
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// Create the image file and open for writing.
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file, err := os.OpenFile(fullImagePath, os.O_CREATE|os.O_EXCL|os.O_RDWR, 0644)
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if err != nil {
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Fatalf("os.OpenFile(%q) failed: %v", fullImagePath, err)
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}
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defer file.Close()
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if err := cont.Checkpoint(file); err != nil {
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Fatalf("checkpoint failed: %v", err)
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}
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if !c.leaveRunning {
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return subcommands.ExitSuccess
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}
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// TODO: Make it possible to restore into same container.
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// For now, we can fake it by destroying the container and making a
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// new container with the same ID. This hack does not work with docker
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// which uses the container pid to ensure that the restore-container is
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// actually the same as the checkpoint-container. By restoring into
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// the same container, we will solve the docker incompatibility.
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// Restore into new container with same ID.
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bundleDir := cont.BundleDir
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if bundleDir == "" {
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Fatalf("setting bundleDir")
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}
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spec, err := specutils.ReadSpec(bundleDir)
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if err != nil {
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Fatalf("reading spec: %v", err)
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}
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specutils.LogSpec(spec)
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if cont.ConsoleSocket != "" {
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log.Warningf("ignoring console socket since it cannot be restored")
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}
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if err := cont.Destroy(); err != nil {
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Fatalf("destroying container: %v", err)
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}
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cont, err = container.Create(id, spec, conf, bundleDir, "", "", "")
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if err != nil {
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Fatalf("restoring container: %v", err)
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}
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defer cont.Destroy()
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if err := cont.Restore(spec, conf, fullImagePath); err != nil {
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Fatalf("starting container: %v", err)
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}
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ws, err := cont.Wait()
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*waitStatus = ws
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return subcommands.ExitSuccess
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}
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