btrfs: auto-detect device
No longer need to set `plugins.snapshot-btrfs.device` manually Signed-off-by: Akihiro Suda <suda.akihiro@lab.ntt.co.jp>
This commit is contained in:
Akihiro Suda
parent
e37c337a3b
commit
d5707d3ac7
@ -7,51 +7,69 @@ import (
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"fmt"
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"os"
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"path/filepath"
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"strings"
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"github.com/Sirupsen/logrus"
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"github.com/containerd/btrfs"
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"github.com/containerd/containerd"
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"github.com/containerd/containerd/log"
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"github.com/containerd/containerd/mountinfo"
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"github.com/containerd/containerd/plugin"
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"github.com/containerd/containerd/snapshot"
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"github.com/containerd/containerd/snapshot/storage"
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"github.com/pkg/errors"
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)
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type btrfsConfig struct {
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Device string `toml:"device"`
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}
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func init() {
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plugin.Register("snapshot-btrfs", &plugin.Registration{
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Type: plugin.SnapshotPlugin,
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Config: &btrfsConfig{},
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Init: func(ic *plugin.InitContext) (interface{}, error) {
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root := filepath.Join(ic.Root, "snapshot", "btrfs")
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conf := ic.Config.(*btrfsConfig)
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if conf.Device == "" {
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// TODO: check device for root
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return nil, errors.Errorf("btrfs requires \"device\" configuration")
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}
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return NewSnapshotter(conf.Device, root)
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return NewSnapshotter(root)
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},
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})
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}
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type snapshotter struct {
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device string // maybe we can resolve it with path?
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device string // device of the root
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root string // root provides paths for internal storage.
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ms *storage.MetaStore
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}
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// NewSnapshotter returns a Snapshotter using btrfs. Uses the provided
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// device and root directory for snapshots and stores the metadata in
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// a file in the provided root.
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func NewSnapshotter(device, root string) (snapshot.Snapshotter, error) {
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if err := os.MkdirAll(root, 0700); err != nil {
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return nil, err
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func getBtrfsDevice(root string, mounts []*mountinfo.Info) (string, error) {
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device := ""
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deviceMountpoint := ""
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for _, info := range mounts {
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if (info.Root == "/" || info.Root == "") && strings.HasPrefix(root, info.Mountpoint) {
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if info.Fstype == "btrfs" && len(info.Mountpoint) > len(deviceMountpoint) {
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device = info.Source
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deviceMountpoint = info.Mountpoint
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}
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if root == info.Mountpoint && info.Fstype != "btrfs" {
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return "", fmt.Errorf("%s needs to be btrfs, but seems %s", root, info.Fstype)
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}
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}
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}
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if device == "" {
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// TODO: automatically mount loopback device here?
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return "", fmt.Errorf("%s is not mounted as btrfs", root)
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}
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return device, nil
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}
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// NewSnapshotter returns a Snapshotter using btrfs. Uses the provided
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// root directory for snapshots and stores the metadata in
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// a file in the provided root.
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// root needs to be a mount point of btrfs.
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func NewSnapshotter(root string) (snapshot.Snapshotter, error) {
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mounts, err := mountinfo.GetMounts()
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if err != nil {
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return nil, err
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}
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device, err := getBtrfsDevice(root, mounts)
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if err != nil {
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return nil, err
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}
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var (
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active = filepath.Join(root, "active")
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snapshots = filepath.Join(root, "snapshots")
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@ -193,7 +211,7 @@ func (b *snapshotter) mounts(dir string) ([]containerd.Mount, error) {
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return []containerd.Mount{
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{
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Type: "btrfs",
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Source: b.device, // device?
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Source: b.device,
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// NOTE(stevvooe): While it would be nice to use to uuids for
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// mounts, they don't work reliably if the uuids are missing.
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Options: options,
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@ -12,6 +12,7 @@ import (
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"testing"
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"github.com/containerd/containerd"
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"github.com/containerd/containerd/mountinfo"
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"github.com/containerd/containerd/snapshot"
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"github.com/containerd/containerd/snapshot/testsuite"
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"github.com/containerd/containerd/testutil"
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@ -24,7 +25,7 @@ const (
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func boltSnapshotter(t *testing.T) func(context.Context, string) (snapshot.Snapshotter, func(), error) {
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return func(ctx context.Context, root string) (snapshot.Snapshotter, func(), error) {
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device := setupBtrfsLoopbackDevice(t, root)
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snapshotter, err := NewSnapshotter(device.deviceName, root)
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snapshotter, err := NewSnapshotter(root)
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if err != nil {
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t.Fatal(err)
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}
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@ -215,3 +216,64 @@ func (device *testDevice) remove(t *testing.T) {
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t.Error(err)
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}
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}
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func TestGetBtrfsDevice(t *testing.T) {
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testCases := []struct {
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expectedDevice string
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expectedError string
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root string
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mounts []*mountinfo.Info
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}{
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{
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expectedDevice: "/dev/loop0",
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root: "/var/lib/containerd/snapshot/btrfs",
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mounts: []*mountinfo.Info{
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{Root: "/", Mountpoint: "/", Fstype: "ext4", Source: "/dev/sda1"},
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{Root: "/", Mountpoint: "/var/lib/containerd/snapshot/btrfs", Fstype: "btrfs", Source: "/dev/loop0"},
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},
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},
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{
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expectedError: "/var/lib/containerd/snapshot/btrfs is not mounted as btrfs",
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root: "/var/lib/containerd/snapshot/btrfs",
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mounts: []*mountinfo.Info{
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{Root: "/", Mountpoint: "/", Fstype: "ext4", Source: "/dev/sda1"},
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},
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},
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{
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expectedDevice: "/dev/sda1",
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root: "/var/lib/containerd/snapshot/btrfs",
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mounts: []*mountinfo.Info{
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{Root: "/", Mountpoint: "/", Fstype: "btrfs", Source: "/dev/sda1"},
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},
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},
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{
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expectedDevice: "/dev/sda2",
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root: "/var/lib/containerd/snapshot/btrfs",
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mounts: []*mountinfo.Info{
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{Root: "/", Mountpoint: "/", Fstype: "btrfs", Source: "/dev/sda1"},
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{Root: "/", Mountpoint: "/var/lib/containerd/snapshot/btrfs", Fstype: "btrfs", Source: "/dev/sda2"},
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},
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},
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{
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expectedDevice: "/dev/sda2",
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root: "/var/lib/containerd/snapshot/btrfs",
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mounts: []*mountinfo.Info{
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{Root: "/", Mountpoint: "/var/lib/containerd/snapshot/btrfs", Fstype: "btrfs", Source: "/dev/sda2"},
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{Root: "/", Mountpoint: "/var/lib/foooooooooooooooooooo/baaaaaaaaaaaaaaaaaaaar", Fstype: "btrfs", Source: "/dev/sda3"}, // mountpoint length longer than /var/lib/containerd/snapshot/btrfs
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{Root: "/", Mountpoint: "/", Fstype: "btrfs", Source: "/dev/sda1"},
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},
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},
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}
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for i, tc := range testCases {
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device, err := getBtrfsDevice(tc.root, tc.mounts)
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if err != nil && tc.expectedError == "" {
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t.Fatalf("%d: expected nil, got %v", i, err)
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}
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if err != nil && !strings.Contains(err.Error(), tc.expectedError) {
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t.Fatalf("%d: expected %s, got %v", i, tc.expectedError, err)
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}
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if err == nil && device != tc.expectedDevice {
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t.Fatalf("%d: expected %s, got %s", i, tc.expectedDevice, device)
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}
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}
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}
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