Merge pull request #405 from samuelkarp/btrfs-test-setup

snapshot: automate btrfs test setup

snapshot/btrfs_test.go

@@ -1,26 +1,32 @@
 package snapshot
 
 import (
+	"bytes"
 	"io/ioutil"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"strings"
 	"testing"
 
 	"github.com/docker/containerd"
+	btrfs "github.com/stevvooe/go-btrfs"
+)
+
+const (
+	mib = 1024 * 1024
 )
 
 func TestBtrfs(t *testing.T) {
-	// SORRY(stevvooe): This is where I mount a btrfs loopback. We can probably
-	// set this up as part of the test.
-	root, err := ioutil.TempDir("/tmp/snapshots", "TestBtrfsPrepare-")
+	device := setupBtrfsLoopbackDevice(t)
+	defer removeBtrfsLoopbackDevice(t, device)
+	root, err := ioutil.TempDir(device.mountPoint, "TestBtrfsPrepare-")
 	if err != nil {
 		t.Fatal(err)
 	}
 	defer os.RemoveAll(root)
-	// TODO(stevvooe): Cleanup subvolumes
 
-	sm, err := NewBtrfs("/dev/loop0", root)
+	sm, err := NewBtrfs(device.deviceName, root)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -47,6 +53,11 @@ func TestBtrfs(t *testing.T) {
 	if err := containerd.MountAll(mounts...); err != nil {
 		t.Fatal(err)
 	}
+	defer func(mounts []containerd.Mount) {
+		for _, mount := range mounts {
+			unmount(t, mount.Target)
+		}
+	}(mounts)
 
 	// write in some data
 	if err := ioutil.WriteFile(filepath.Join(mounts[0].Target, "foo"), []byte("content"), 0777); err != nil {
@@ -62,6 +73,13 @@ func TestBtrfs(t *testing.T) {
 	if err := sm.Commit(filepath.Join(root, "snapshots/committed"), filepath.Join(root, "test")); err != nil {
 		t.Fatal(err)
 	}
+	defer func() {
+		t.Log("Delete snapshot 1")
+		err := btrfs.SubvolDelete(filepath.Join(root, "snapshots/committed"))
+		if err != nil {
+			t.Error("snapshot delete failed", err)
+		}
+	}()
 
 	mounts, err = sm.Prepare(filepath.Join(root, "test2"), filepath.Join(root, "snapshots/committed"))
 	if err != nil {
@@ -75,6 +93,11 @@ func TestBtrfs(t *testing.T) {
 	if err := containerd.MountAll(mounts...); err != nil {
 		t.Fatal(err)
 	}
+	defer func(mounts []containerd.Mount) {
+		for _, mount := range mounts {
+			unmount(t, mount.Target)
+		}
+	}(mounts)
 
 	// TODO(stevvooe): Verify contents of "foo"
 	if err := ioutil.WriteFile(filepath.Join(mounts[0].Target, "bar"), []byte("content"), 0777); err != nil {
@@ -84,4 +107,120 @@ func TestBtrfs(t *testing.T) {
 	if err := sm.Commit(filepath.Join(root, "snapshots/committed2"), filepath.Join(root, "test2")); err != nil {
 		t.Fatal(err)
 	}
+	defer func() {
+		t.Log("Delete snapshot 2")
+		err := btrfs.SubvolDelete(filepath.Join(root, "snapshots/committed2"))
+		if err != nil {
+			t.Error("snapshot delete failed", err)
+		}
+	}()
+}
+
+type testDevice struct {
+	mountPoint string
+	fileName   string
+	deviceName string
+}
+
+// setupBtrfsLoopbackDevice creates a file, mounts it as a loopback device, and
+// formats it as btrfs.  The device should be cleaned up by calling
+// removeBtrfsLoopbackDevice.
+func setupBtrfsLoopbackDevice(t *testing.T) *testDevice {
+	// create temporary directory for mount point
+	mountPoint, err := ioutil.TempDir("", "containerd-btrfs-test")
+	if err != nil {
+		t.Fatal("Could not create mount point for btrfs test", err)
+	}
+	t.Log("Temporary mount point created", mountPoint)
+
+	// create temporary file for the disk image
+	file, err := ioutil.TempFile("", "containerd-btrfs-test")
+	if err != nil {
+		t.Fatal("Could not create temporary file for btrfs test", err)
+	}
+	t.Log("Temporary file created", file.Name())
+
+	// initialize file with 100 MiB
+	zero := [mib]byte{}
+	for i := 0; i < 100; i++ {
+		_, err = file.Write(zero[:])
+		if err != nil {
+			t.Fatal("Could not write to btrfs file", err)
+		}
+	}
+	file.Close()
+
+	// create device
+	losetup := exec.Command("losetup", "--find", "--show", file.Name())
+	var stdout, stderr bytes.Buffer
+	losetup.Stdout = &stdout
+	losetup.Stderr = &stderr
+	err = losetup.Run()
+	if err != nil {
+		t.Log(stderr.String())
+		t.Fatal("Could not run losetup", err)
+	}
+	deviceName := strings.TrimSpace(stdout.String())
+	t.Log("Created loop device", deviceName)
+
+	// format
+	t.Log("Creating btrfs filesystem")
+	mkfs := exec.Command("mkfs.btrfs", deviceName)
+	err = mkfs.Run()
+	if err != nil {
+		t.Fatal("Could not run mkfs.btrfs", err)
+	}
+
+	// mount
+	t.Logf("Mounting %s at %s", deviceName, mountPoint)
+	mount := exec.Command("mount", deviceName, mountPoint)
+	err = mount.Run()
+	if err != nil {
+		t.Fatal("Could not mount", err)
+	}
+
+	return &testDevice{
+		mountPoint: mountPoint,
+		fileName:   file.Name(),
+		deviceName: deviceName,
+	}
+}
+
+// removeBtrfsLoopbackDevice unmounts the loopback device and deletes the
+// file holding the disk image.
+func removeBtrfsLoopbackDevice(t *testing.T, device *testDevice) {
+	// unmount
+	unmount(t, device.mountPoint)
+
+	// detach device
+	t.Log("Removing loop device")
+	losetup := exec.Command("losetup", "--detach", device.deviceName)
+	err := losetup.Run()
+	if err != nil {
+		t.Error("Could not remove loop device", device.deviceName, err)
+	}
+
+	// remove file
+	t.Log("Removing temporary file")
+	err = os.Remove(device.fileName)
+	if err != nil {
+		t.Error(err)
+	}
+
+	// remove mount point
+	t.Log("Removing temporary mount point")
+	err = os.RemoveAll(device.mountPoint)
+	if err != nil {
+		t.Error(err)
+	}
+}
+
+func unmount(t *testing.T, mountPoint string) {
+	t.Log("unmount", mountPoint)
+	umount := exec.Command("umount", mountPoint)
+	err := umount.Run()
+	if err != nil {
+
+		t.Error("Could not umount", mountPoint, err)
+	}
 }