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Merge pull request #532 from dmcgowan/snapshot-overlay-view

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Snapshot overlay view
This commit is contained in:
Stephen Day 2017-02-27 13:53:27 -08:00 committed by GitHub
commit 4edcaa32be
2 changed files with 144 additions and 13 deletions
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61
snapshot/overlay/overlay.go
View file

@ -102,7 +102,7 @@ func (o *Snapshotter) stat(path string) (snapshot.Info, error) {
}
func (o *Snapshotter) Prepare(ctx context.Context, key, parent string) ([]containerd.Mount, error) {
active, err := o.newActiveDir(key)
active, err := o.newActiveDir(key, false)
if err != nil {
return nil, err
}
@ -115,7 +115,16 @@ func (o *Snapshotter) Prepare(ctx context.Context, key, parent string) ([]contai
}
func (o *Snapshotter) View(ctx context.Context, key, parent string) ([]containerd.Mount, error) {
panic("not implemented")
active, err := o.newActiveDir(key, true)
if err != nil {
return nil, err
}
if parent != "" {
if err := active.setParent(parent); err != nil {
return nil, err
}
}
return active.mounts(o.links)
}
// Mounts returns the mounts for the transaction identified by key. Can be
@ -175,7 +184,7 @@ func (o *Snapshotter) Walk(ctx context.Context, fn func(context.Context, snapsho
})
}
func (o *Snapshotter) newActiveDir(key string) (*activeDir, error) {
func (o *Snapshotter) newActiveDir(key string, readonly bool) (*activeDir, error) {
var (
path = filepath.Join(o.root, "active", hash(key))
name = filepath.Join(path, "name")
@ -186,6 +195,7 @@ func (o *Snapshotter) newActiveDir(key string) (*activeDir, error) {
committedDir: filepath.Join(o.root, "committed"),
indexlink: indexlink,
}
if !readonly {
for _, p := range []string{
"work",
"fs",
@ -195,6 +205,12 @@ func (o *Snapshotter) newActiveDir(key string) (*activeDir, error) {
return nil, err
}
}
} else {
if err := os.MkdirAll(filepath.Join(path, "fs"), 0700); err != nil {
a.delete()
return nil, err
}
}
if err := ioutil.WriteFile(name, []byte(key), 0644); err != nil {
a.delete()
@ -237,6 +253,13 @@ func (a *activeDir) setParent(name string) error {
}
func (a *activeDir) commit(name string, c *cache) error {
if _, err := os.Stat(filepath.Join(a.path, "fs")); err != nil {
if os.IsNotExist(err) {
return errors.New("cannot commit view")
}
return err
}
// TODO(stevvooe): This doesn't quite meet the current model. The new model
// is to copy all of this out and let the transaction continue. We don't
// really have tests for it yet, but this will be the spot to fix it.
@ -287,22 +310,48 @@ func (a *activeDir) mounts(c *cache) ([]containerd.Mount, error) {
if len(parents) == 0 {
// if we only have one layer/no parents then just return a bind mount as overlay
// will not work
roFlag := "rw"
if _, err := os.Stat(filepath.Join(a.path, "work")); err != nil {
if !os.IsNotExist(err) {
return nil, err
}
roFlag = "ro"
}
return []containerd.Mount{
{
Source: filepath.Join(a.path, "fs"),
Type: "bind",
Options: []string{
"rw",
roFlag,
"rbind",
},
},
}, nil
}
options := []string{
var options []string
if _, err := os.Stat(filepath.Join(a.path, "work")); err == nil {
options = append(options,
fmt.Sprintf("workdir=%s", filepath.Join(a.path, "work")),
fmt.Sprintf("upperdir=%s", filepath.Join(a.path, "fs")),
fmt.Sprintf("lowerdir=%s", strings.Join(parents, ":")),
)
} else if !os.IsNotExist(err) {
return nil, err
} else if len(parents) == 1 {
return []containerd.Mount{
{
Source: parents[0],
Type: "bind",
Options: []string{
"ro",
"rbind",
},
},
}, nil
}
options = append(options, fmt.Sprintf("lowerdir=%s", strings.Join(parents, ":")))
return []containerd.Mount{
{
Type: "overlay",

82
snapshot/overlay/overlay_test.go
View file

@ -2,6 +2,7 @@ package overlay
import (
"context"
"fmt"
"io/ioutil"
"os"
"path/filepath"
@ -196,3 +197,84 @@ func TestOverlayOverlayRead(t *testing.T) {
return
}
}
func TestOverlayView(t *testing.T) {
ctx := context.TODO()
root, err := ioutil.TempDir("", "overlay")
if err != nil {
t.Fatal(err)
}
defer os.RemoveAll(root)
o, err := NewSnapshotter(root)
if err != nil {
t.Fatal(err)
}
key := "/tmp/base"
mounts, err := o.Prepare(ctx, key, "")
if err != nil {
t.Fatal(err)
}
m := mounts[0]
if err := ioutil.WriteFile(filepath.Join(m.Source, "foo"), []byte("hi"), 0660); err != nil {
t.Fatal(err)
}
if err := o.Commit(ctx, "base", key); err != nil {
t.Fatal(err)
}
key = "/tmp/top"
_, err = o.Prepare(ctx, key, "base")
if err != nil {
t.Fatal(err)
}
if err := ioutil.WriteFile(filepath.Join(root, "active", hash(key), "fs", "foo"), []byte("hi, again"), 0660); err != nil {
t.Fatal(err)
}
if err := o.Commit(ctx, "top", key); err != nil {
t.Fatal(err)
}
mounts, err = o.View(ctx, "/tmp/view1", "base")
if err != nil {
t.Fatal(err)
}
if len(mounts) != 1 {
t.Fatalf("should only have 1 mount but received %d", len(mounts))
}
m = mounts[0]
if m.Type != "bind" {
t.Errorf("mount type should be bind but received %q", m.Type)
}
expected := filepath.Join(root, "committed", hash("base"), "fs")
if m.Source != expected {
t.Errorf("expected source %q but received %q", expected, m.Source)
}
if m.Options[0] != "ro" {
t.Errorf("expected mount option ro but received %q", m.Options[0])
}
if m.Options[1] != "rbind" {
t.Errorf("expected mount option rbind but received %q", m.Options[1])
}
mounts, err = o.View(ctx, "/tmp/view2", "top")
if err != nil {
t.Fatal(err)
}
if len(mounts) != 1 {
t.Fatalf("should only have 1 mount but received %d", len(mounts))
}
m = mounts[0]
if m.Type != "overlay" {
t.Errorf("mount type should be overlay but received %q", m.Type)
}
if m.Source != "overlay" {
t.Errorf("mount source should be overlay but received %q", m.Source)
}
if len(m.Options) != 1 {
t.Errorf("expected 1 mount option but got %d", len(m.Options))
}
expected = fmt.Sprintf("lowerdir=%s:%s", filepath.Join(root, "committed", hash("top"), "fs"), filepath.Join(root, "committed", hash("base"), "fs"))
if m.Options[0] != expected {
t.Errorf("expected option %q but received %q", expected, m.Options[0])
}
}