Merge pull request #2272 from adrianreber/migration

Add support to migrate containers

1 files changed, 145 insertions, 0 deletions

diff --git a/pkg/adapter/checkpoint_restore.go b/pkg/adapter/checkpoint_restore.go
new file mode 100644
index 000000000..97ba5ecf7
--- /dev/null
+++ b/pkg/adapter/checkpoint_restore.go
@@ -0,0 +1,145 @@
+// +build !remoteclient
+
+package adapter
+
+import (
+	"context"
+	"github.com/containers/libpod/libpod"
+	"github.com/containers/libpod/libpod/image"
+	"github.com/containers/storage/pkg/archive"
+	jsoniter "github.com/json-iterator/go"
+	spec "github.com/opencontainers/runtime-spec/specs-go"
+	"github.com/pkg/errors"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+)
+
+// Prefixing the checkpoint/restore related functions with 'cr'
+
+// crImportFromJSON imports the JSON files stored in the exported
+// checkpoint tarball
+func crImportFromJSON(filePath string, v interface{}) error {
+	jsonFile, err := os.Open(filePath)
+	if err != nil {
+		return errors.Wrapf(err, "Failed to open container definition %s for restore", filePath)
+	}
+	defer jsonFile.Close()
+
+	content, err := ioutil.ReadAll(jsonFile)
+	if err != nil {
+		return errors.Wrapf(err, "Failed to read container definition %s for restore", filePath)
+	}
+	json := jsoniter.ConfigCompatibleWithStandardLibrary
+	if err = json.Unmarshal([]byte(content), v); err != nil {
+		return errors.Wrapf(err, "Failed to unmarshal container definition %s for restore", filePath)
+	}
+
+	return nil
+}
+
+// crImportCheckpoint it the function which imports the information
+// from checkpoint tarball and re-creates the container from that information
+func crImportCheckpoint(ctx context.Context, runtime *libpod.Runtime, input string, name string) ([]*libpod.Container, error) {
+	// First get the container definition from the
+	// tarball to a temporary directory
+	archiveFile, err := os.Open(input)
+	if err != nil {
+		return nil, errors.Wrapf(err, "Failed to open checkpoint archive %s for import", input)
+	}
+	defer archiveFile.Close()
+	options := &archive.TarOptions{
+		// Here we only need the files config.dump and spec.dump
+		ExcludePatterns: []string{
+			"checkpoint",
+			"artifacts",
+			"ctr.log",
+			"network.status",
+		},
+	}
+	dir, err := ioutil.TempDir("", "checkpoint")
+	if err != nil {
+		return nil, err
+	}
+	defer os.RemoveAll(dir)
+	err = archive.Untar(archiveFile, dir, options)
+	if err != nil {
+		return nil, errors.Wrapf(err, "Unpacking of checkpoint archive %s failed", input)
+	}
+
+	// Load spec.dump from temporary directory
+	spec := new(spec.Spec)
+	if err := crImportFromJSON(filepath.Join(dir, "spec.dump"), spec); err != nil {
+		return nil, err
+	}
+
+	// Load config.dump from temporary directory
+	config := new(libpod.ContainerConfig)
+	if err = crImportFromJSON(filepath.Join(dir, "config.dump"), config); err != nil {
+		return nil, err
+	}
+
+	// This should not happen as checkpoints with these options are not exported.
+	if (len(config.Dependencies) > 0) || (len(config.NamedVolumes) > 0) {
+		return nil, errors.Errorf("Cannot import checkpoints of containers with named volumes or dependencies")
+	}
+
+	ctrID := config.ID
+	newName := false
+
+	// Check if the restored container gets a new name
+	if name != "" {
+		config.ID = ""
+		config.Name = name
+		newName = true
+	}
+
+	ctrName := config.Name
+
+	// The code to load the images is copied from create.go
+	var writer io.Writer
+	// In create.go this only set if '--quiet' does not exist.
+	writer = os.Stderr
+	rtc, err := runtime.GetConfig()
+	if err != nil {
+		return nil, err
+	}
+
+	_, err = runtime.ImageRuntime().New(ctx, config.RootfsImageName, rtc.SignaturePolicyPath, "", writer, nil, image.SigningOptions{}, false, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	// Now create a new container from the just loaded information
+	container, err := runtime.RestoreContainer(ctx, spec, config)
+	if err != nil {
+		return nil, err
+	}
+
+	var containers []*libpod.Container
+	if container == nil {
+		return nil, nil
+	}
+
+	containerConfig := container.Config()
+	if containerConfig.Name != ctrName {
+		return nil, errors.Errorf("Name of restored container (%s) does not match requested name (%s)", containerConfig.Name, ctrName)
+	}
+
+	if newName == false {
+		// Only check ID for a restore with the same name.
+		// Using -n to request a new name for the restored container, will also create a new ID
+		if containerConfig.ID != ctrID {
+			return nil, errors.Errorf("ID of restored container (%s) does not match requested ID (%s)", containerConfig.ID, ctrID)
+		}
+	}
+
+	// Check if the ExitCommand points to the correct container ID
+	if containerConfig.ExitCommand[len(containerConfig.ExitCommand)-1] != containerConfig.ID {
+		return nil, errors.Errorf("'ExitCommandID' uses ID %s instead of container ID %s", containerConfig.ExitCommand[len(containerConfig.ExitCommand)-1], containerConfig.ID)
+	}
+
+	containers = append(containers, container)
+	return containers, nil
+}