Merge pull request #567 from samuelkarp/snapshotter-context

snapshot: Add context to Snapshotter interface

rootfs/apply.go

@@ -30,6 +30,7 @@ type Mounter interface {
 func ApplyLayer(snapshots snapshot.Snapshotter, mounter Mounter, rd io.Reader, parent digest.Digest) (digest.Digest, error) {
 	digester := digest.Canonical.Digester() // used to calculate diffID.
 	rd = io.TeeReader(rd, digester.Hash())
+	ctx := context.TODO()
 
 	// create a temporary directory to work from, needs to be on same
 	// filesystem. Probably better if this shared but we'll use a tempdir, for
@@ -45,13 +46,13 @@ func ApplyLayer(snapshots snapshot.Snapshotter, mounter Mounter, rd io.Reader, p
 	// layerID (since we don't know the diffID until we are done!).
 	key := dir
 
-	mounts, err := snapshots.Prepare(key, parent.String())
+	mounts, err := snapshots.Prepare(ctx, key, parent.String())
 	if err != nil {
 		return "", err
 	}
 
 	if err := mounter.Mount(mounts...); err != nil {
-		if err := snapshots.Remove(key); err != nil {
+		if err := snapshots.Remove(ctx, key); err != nil {
 			log.L.WithError(err).Error("snapshot rollback failed")
 		}
 		return "", err
@@ -74,7 +75,7 @@ func ApplyLayer(snapshots snapshot.Snapshotter, mounter Mounter, rd io.Reader, p
 		chainID = identity.ChainID([]digest.Digest{parent, chainID})
 	}
 
-	return diffID, snapshots.Commit(chainID.String(), key)
+	return diffID, snapshots.Commit(ctx, chainID.String(), key)
 }
 
 // Prepare the root filesystem from the set of layers. Snapshots are created
@@ -83,7 +84,7 @@ func ApplyLayer(snapshots snapshot.Snapshotter, mounter Mounter, rd io.Reader, p
 //
 // If successful, the chainID for the top-level layer is returned. That
 // identifier can be used to check out a snapshot.
-func Prepare(snapshots snapshot.Snapshotter, mounter Mounter, layers []ocispec.Descriptor,
+func Prepare(ctx context.Context, snapshots snapshot.Snapshotter, mounter Mounter, layers []ocispec.Descriptor,
 	// TODO(stevvooe): The following functions are candidate for internal
 	// object functions. We can use these to formulate the beginnings of a
 	// rootfs Controller.
@@ -110,7 +111,7 @@ func Prepare(snapshots snapshot.Snapshotter, mounter Mounter, layers []ocispec.D
 			chainLocal := append(chain, diffID)
 			chainID := identity.ChainID(chainLocal)
 
-			if _, err := snapshots.Stat(chainID.String()); err == nil {
+			if _, err := snapshots.Stat(ctx, chainID.String()); err == nil {
 				continue
 			}
 		}

snapshot/btrfs/btrfs.go

@@ -1,6 +1,7 @@
 package btrfs
 
 import (
+	"context"
 	"crypto/sha256"
 	"fmt"
 	"io/ioutil"
@@ -48,7 +49,7 @@ func NewSnapshotter(device, root string) (*Snapshotter, error) {
 //
 // Should be used for parent resolution, existence checks and to discern
 // the kind of snapshot.
-func (b *Snapshotter) Stat(key string) (snapshot.Info, error) {
+func (b *Snapshotter) Stat(ctx context.Context, key string) (snapshot.Info, error) {
 	// resolve the snapshot out of the index.
 	target, err := os.Readlink(filepath.Join(b.root, "index", hash(key)))
 	if err != nil {
@@ -119,11 +120,11 @@ func (b *Snapshotter) stat(target string) (snapshot.Info, error) {
 
 }
 
-func (b *Snapshotter) Prepare(key, parent string) ([]containerd.Mount, error) {
+func (b *Snapshotter) Prepare(ctx context.Context, key, parent string) ([]containerd.Mount, error) {
 	return b.makeActive(key, parent, false)
 }
 
-func (b *Snapshotter) View(key, parent string) ([]containerd.Mount, error) {
+func (b *Snapshotter) View(ctx context.Context, key, parent string) ([]containerd.Mount, error) {
 	return b.makeActive(key, parent, true)
 }
 
@@ -198,7 +199,7 @@ func (b *Snapshotter) mounts(dir string) ([]containerd.Mount, error) {
 	}, nil
 }
 
-func (b *Snapshotter) Commit(name, key string) error {
+func (b *Snapshotter) Commit(ctx context.Context, name, key string) error {
 	var (
 		active        = filepath.Join(b.root, "active")
 		snapshots     = filepath.Join(b.root, "snapshots")
@@ -283,19 +284,19 @@ func (b *Snapshotter) Commit(name, key string) error {
 // called on an read-write or readonly transaction.
 //
 // This can be used to recover mounts after calling View or Prepare.
-func (b *Snapshotter) Mounts(key string) ([]containerd.Mount, error) {
+func (b *Snapshotter) Mounts(ctx context.Context, key string) ([]containerd.Mount, error) {
 	dir := filepath.Join(b.root, "active", hash(key))
 	return b.mounts(dir)
 }
 
 // Remove abandons the transaction identified by key. All resources
 // associated with the key will be removed.
-func (b *Snapshotter) Remove(key string) error {
+func (b *Snapshotter) Remove(ctx context.Context, key string) error {
 	panic("not implemented")
 }
 
 // Walk the committed snapshots.
-func (b *Snapshotter) Walk(fn func(snapshot.Info) error) error {
+func (b *Snapshotter) Walk(ctx context.Context, fn func(context.Context, snapshot.Info) error) error {
 	// TODO(stevvooe): Copy-pasted almost verbatim from overlay. Really need to
 	// unify the metadata for snapshot implementations.
 	root := filepath.Join(b.root, "index")
@@ -325,7 +326,7 @@ func (b *Snapshotter) Walk(fn func(snapshot.Info) error) error {
 			return err
 		}
 
-		if err := fn(si); err != nil {
+		if err := fn(ctx, si); err != nil {
 			return err
 		}
 

snapshot/btrfs/btrfs_test.go

@@ -1,6 +1,7 @@
 package btrfs
 
 import (
+	"context"
 	"io/ioutil"
 	"os"
 	"os/exec"
@@ -34,6 +35,7 @@ func TestBtrfs(t *testing.T) {
 
 func TestBtrfsMounts(t *testing.T) {
 	testutil.RequiresRoot(t)
+	ctx := context.TODO()
 
 	// create temporary directory for mount point
 	mountPoint, err := ioutil.TempDir("", "containerd-btrfs-test")
@@ -56,7 +58,7 @@ func TestBtrfsMounts(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	mounts, err := b.Prepare(target, "")
+	mounts, err := b.Prepare(ctx, target, "")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -92,12 +94,12 @@ func TestBtrfsMounts(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	if err := b.Commit(filepath.Join(root, "snapshots/committed"), filepath.Join(root, "test")); err != nil {
+	if err := b.Commit(ctx, filepath.Join(root, "snapshots/committed"), filepath.Join(root, "test")); err != nil {
 		t.Fatal(err)
 	}
 
 	target = filepath.Join(root, "test2")
-	mounts, err = b.Prepare(target, filepath.Join(root, "snapshots/committed"))
+	mounts, err = b.Prepare(ctx, target, filepath.Join(root, "snapshots/committed"))
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -116,7 +118,7 @@ func TestBtrfsMounts(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	if err := b.Commit(filepath.Join(root, "snapshots/committed2"), target); err != nil {
+	if err := b.Commit(ctx, filepath.Join(root, "snapshots/committed2"), target); err != nil {
 		t.Fatal(err)
 	}
 }

snapshot/overlay/overlay.go

@@ -1,6 +1,7 @@
 package overlay
 
 import (
+	"context"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -43,7 +44,7 @@ func NewSnapshotter(root string) (*Snapshotter, error) {
 //
 // Should be used for parent resolution, existence checks and to discern
 // the kind of snapshot.
-func (o *Snapshotter) Stat(key string) (snapshot.Info, error) {
+func (o *Snapshotter) Stat(ctx context.Context, key string) (snapshot.Info, error) {
 	path, err := o.links.get(filepath.Join(o.root, "index", hash(key)))
 	if err != nil {
 		if !os.IsNotExist(err) {
@@ -100,7 +101,7 @@ func (o *Snapshotter) stat(path string) (snapshot.Info, error) {
 	}, nil
 }
 
-func (o *Snapshotter) Prepare(key, parent string) ([]containerd.Mount, error) {
+func (o *Snapshotter) Prepare(ctx context.Context, key, parent string) ([]containerd.Mount, error) {
 	active, err := o.newActiveDir(key)
 	if err != nil {
 		return nil, err
@@ -113,7 +114,7 @@ func (o *Snapshotter) Prepare(key, parent string) ([]containerd.Mount, error) {
 	return active.mounts(o.links)
 }
 
-func (o *Snapshotter) View(key, parent string) ([]containerd.Mount, error) {
+func (o *Snapshotter) View(ctx context.Context, key, parent string) ([]containerd.Mount, error) {
 	panic("not implemented")
 }
 
@@ -121,24 +122,24 @@ func (o *Snapshotter) View(key, parent string) ([]containerd.Mount, error) {
 // called on an read-write or readonly transaction.
 //
 // This can be used to recover mounts after calling View or Prepare.
-func (o *Snapshotter) Mounts(key string) ([]containerd.Mount, error) {
+func (o *Snapshotter) Mounts(ctx context.Context, key string) ([]containerd.Mount, error) {
 	active := o.getActive(key)
 	return active.mounts(o.links)
 }
 
-func (o *Snapshotter) Commit(name, key string) error {
+func (o *Snapshotter) Commit(ctx context.Context, name, key string) error {
 	active := o.getActive(key)
 	return active.commit(name, o.links)
 }
 
 // Remove abandons the transaction identified by key. All resources
 // associated with the key will be removed.
-func (o *Snapshotter) Remove(key string) error {
+func (o *Snapshotter) Remove(ctx context.Context, key string) error {
 	panic("not implemented")
 }
 
 // Walk the committed snapshots.
-func (o *Snapshotter) Walk(fn func(snapshot.Info) error) error {
+func (o *Snapshotter) Walk(ctx context.Context, fn func(context.Context, snapshot.Info) error) error {
 	root := filepath.Join(o.root, "index")
 	return filepath.Walk(root, func(path string, fi os.FileInfo, err error) error {
 		if err != nil {
@@ -166,7 +167,7 @@ func (o *Snapshotter) Walk(fn func(snapshot.Info) error) error {
 			return err
 		}
 
-		if err := fn(si); err != nil {
+		if err := fn(ctx, si); err != nil {
 			return err
 		}
 

snapshot/overlay/overlay_test.go

@@ -1,6 +1,7 @@
 package overlay
 
 import (
+	"context"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -25,6 +26,7 @@ func TestOverlay(t *testing.T) {
 }
 
 func TestOverlayMounts(t *testing.T) {
+	ctx := context.TODO()
 	root, err := ioutil.TempDir("", "overlay")
 	if err != nil {
 		t.Fatal(err)
@@ -35,7 +37,7 @@ func TestOverlayMounts(t *testing.T) {
 		t.Error(err)
 		return
 	}
-	mounts, err := o.Prepare("/tmp/test", "")
+	mounts, err := o.Prepare(ctx, "/tmp/test", "")
 	if err != nil {
 		t.Error(err)
 		return
@@ -60,6 +62,7 @@ func TestOverlayMounts(t *testing.T) {
 }
 
 func TestOverlayCommit(t *testing.T) {
+	ctx := context.TODO()
 	root, err := ioutil.TempDir("", "overlay")
 	if err != nil {
 		t.Fatal(err)
@@ -71,7 +74,7 @@ func TestOverlayCommit(t *testing.T) {
 		return
 	}
 	key := "/tmp/test"
-	mounts, err := o.Prepare(key, "")
+	mounts, err := o.Prepare(ctx, key, "")
 	if err != nil {
 		t.Error(err)
 		return
@@ -81,13 +84,14 @@ func TestOverlayCommit(t *testing.T) {
 		t.Error(err)
 		return
 	}
-	if err := o.Commit("base", key); err != nil {
+	if err := o.Commit(ctx, "base", key); err != nil {
 		t.Error(err)
 		return
 	}
 }
 
 func TestOverlayOverlayMount(t *testing.T) {
+	ctx := context.TODO()
 	root, err := ioutil.TempDir("", "overlay")
 	if err != nil {
 		t.Fatal(err)
@@ -99,16 +103,16 @@ func TestOverlayOverlayMount(t *testing.T) {
 		return
 	}
 	key := "/tmp/test"
-	mounts, err := o.Prepare(key, "")
+	mounts, err := o.Prepare(ctx, key, "")
 	if err != nil {
 		t.Error(err)
 		return
 	}
-	if err := o.Commit("base", key); err != nil {
+	if err := o.Commit(ctx, "base", key); err != nil {
 		t.Error(err)
 		return
 	}
-	if mounts, err = o.Prepare("/tmp/layer2", "base"); err != nil {
+	if mounts, err = o.Prepare(ctx, "/tmp/layer2", "base"); err != nil {
 		t.Error(err)
 		return
 	}
@@ -142,6 +146,7 @@ func TestOverlayOverlayMount(t *testing.T) {
 
 func TestOverlayOverlayRead(t *testing.T) {
 	testutil.RequiresRoot(t)
+	ctx := context.TODO()
 	root, err := ioutil.TempDir("", "overlay")
 	if err != nil {
 		t.Fatal(err)
@@ -153,7 +158,7 @@ func TestOverlayOverlayRead(t *testing.T) {
 		return
 	}
 	key := "/tmp/test"
-	mounts, err := o.Prepare(key, "")
+	mounts, err := o.Prepare(ctx, key, "")
 	if err != nil {
 		t.Error(err)
 		return
@@ -163,11 +168,11 @@ func TestOverlayOverlayRead(t *testing.T) {
 		t.Error(err)
 		return
 	}
-	if err := o.Commit("base", key); err != nil {
+	if err := o.Commit(ctx, "base", key); err != nil {
 		t.Error(err)
 		return
 	}
-	if mounts, err = o.Prepare("/tmp/layer2", "base"); err != nil {
+	if mounts, err = o.Prepare(ctx, "/tmp/layer2", "base"); err != nil {
 		t.Error(err)
 		return
 	}

snapshot/snapshotter.go

@@ -1,6 +1,7 @@
 package snapshot
 
 import (
+	"context"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -148,14 +149,14 @@ type Snapshotter interface {
 	//
 	// Should be used for parent resolution, existence checks and to discern
 	// the kind of snapshot.
-	Stat(key string) (Info, error)
+	Stat(ctx context.Context, key string) (Info, error)
 
 	// Mounts returns the mounts for the active snapshot transaction identified
 	// by key. Can be called on an read-write or readonly transaction. This is
 	// available only for active snapshots.
 	//
 	// This can be used to recover mounts after calling View or Prepare.
-	Mounts(key string) ([]containerd.Mount, error)
+	Mounts(ctx context.Context, key string) ([]containerd.Mount, error)
 
 	// Prepare creates an active snapshot identified by key descending from the
 	// provided parent.  The returned mounts can be used to mount the snapshot
@@ -171,7 +172,7 @@ type Snapshotter interface {
 	// one is done with the transaction, Remove should be called on the key.
 	//
 	// Multiple calls to Prepare or View with the same key should fail.
-	Prepare(key, parent string) ([]containerd.Mount, error)
+	Prepare(ctx context.Context, key, parent string) ([]containerd.Mount, error)
 
 	// View behaves identically to Prepare except the result may not be
 	// committed back to the snapshot snapshotter. View returns a readonly view on
@@ -186,7 +187,7 @@ type Snapshotter interface {
 	// Commit may not be called on the provided key and will return an error.
 	// To collect the resources associated with key, Remove must be called with
 	// key as the argument.
-	View(key, parent string) ([]containerd.Mount, error)
+	View(ctx context.Context, key, parent string) ([]containerd.Mount, error)
 
 	// Commit captures the changes between key and its parent into a snapshot
 	// identified by name.  The name can then be used with the snapshotter's other
@@ -198,7 +199,7 @@ type Snapshotter interface {
 	// Commit may be called multiple times on the same key. Snapshots created
 	// in this manner will all reference the parent used to start the
 	// transaction.
-	Commit(name, key string) error
+	Commit(ctx context.Context, name, key string) error
 
 	// Remove the committed or active snapshot by the provided key.
 	//
@@ -206,11 +207,11 @@ type Snapshotter interface {
 	//
 	// If the snapshot is a parent of another snapshot, its children must be
 	// removed before proceeding.
-	Remove(key string) error
+	Remove(ctx context.Context, key string) error
 
 	// Walk the committed snapshots. For each snapshot in the snapshotter, the
 	// function will be called.
-	Walk(fn func(Info) error) error
+	Walk(ctx context.Context, fn func(context.Context, Info) error) error
 }
 
 // SnapshotterSuite runs a test suite on the snapshotter given a factory function.
@@ -255,12 +256,13 @@ func makeTest(t *testing.T, name string, snapshotterFn func(root string) (Snapsh
 
 // checkSnapshotterBasic tests the basic workflow of a snapshot snapshotter.
 func checkSnapshotterBasic(t *testing.T, snapshotter Snapshotter, work string) {
+	ctx := context.TODO()
 	preparing := filepath.Join(work, "preparing")
 	if err := os.MkdirAll(preparing, 0777); err != nil {
 		t.Fatal(err)
 	}
 
-	mounts, err := snapshotter.Prepare(preparing, "")
+	mounts, err := snapshotter.Prepare(ctx, preparing, "")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -283,11 +285,11 @@ func checkSnapshotterBasic(t *testing.T, snapshotter Snapshotter, work string) {
 	}
 
 	committed := filepath.Join(work, "committed")
-	if err := snapshotter.Commit(committed, preparing); err != nil {
+	if err := snapshotter.Commit(ctx, committed, preparing); err != nil {
 		t.Fatal(err)
 	}
 
-	si, err := snapshotter.Stat(committed)
+	si, err := snapshotter.Stat(ctx, committed)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -299,7 +301,7 @@ func checkSnapshotterBasic(t *testing.T, snapshotter Snapshotter, work string) {
 		t.Fatal(err)
 	}
 
-	mounts, err = snapshotter.Prepare(next, committed)
+	mounts, err = snapshotter.Prepare(ctx, next, committed)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -322,11 +324,11 @@ func checkSnapshotterBasic(t *testing.T, snapshotter Snapshotter, work string) {
 	}
 
 	nextCommitted := filepath.Join(work, "committed-next")
-	if err := snapshotter.Commit(nextCommitted, next); err != nil {
+	if err := snapshotter.Commit(ctx, nextCommitted, next); err != nil {
 		t.Fatal(err)
 	}
 
-	si2, err := snapshotter.Stat(nextCommitted)
+	si2, err := snapshotter.Stat(ctx, nextCommitted)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -338,7 +340,7 @@ func checkSnapshotterBasic(t *testing.T, snapshotter Snapshotter, work string) {
 		si2.Name: si2,
 	}
 	walked := map[string]Info{} // walk is not ordered
-	assert.NoError(t, snapshotter.Walk(func(si Info) error {
+	assert.NoError(t, snapshotter.Walk(ctx, func(ctx context.Context, si Info) error {
 		walked[si.Name] = si
 		return nil
 	}))