o/snapstate, overlord, o/devicestate: support downloading components …

…in snapstate.Download

overlord/devicestate/devicestate.go

@@ -1764,15 +1764,14 @@ func CreateRecoverySystem(st *state.State, label string, opts CreateRecoverySyst
 			continue
 		}
 
-		const userID = 0
 		// TODO: this respects the passed in validation sets, but does not
 		// currently respect refresh-control style of constraining snap
 		// revisions.
-		ts, info, err := snapstateDownload(context.TODO(), st, sn.Name, dirs.SnapBlobDir, &snapstate.RevisionOptions{
+		ts, info, err := snapstateDownload(context.TODO(), st, sn.Name, nil, dirs.SnapBlobDir, snapstate.RevisionOptions{
 			Channel:        sn.DefaultChannel,
 			Revision:       rev,
 			ValidationSets: valsets,
-		}, userID, snapstate.Flags{}, nil)
+		}, snapstate.Options{})
 		if err != nil {
 			return nil, err
 		}

overlord/devicestate/devicestate_systems_test.go

@@ -3465,20 +3465,20 @@ func (s *deviceMgrSystemsCreateSuite) testDeviceManagerCreateRecoverySystemValid
 	}, nil)
 
 	devicestate.MockSnapstateDownload(func(
-		_ context.Context, _ *state.State, name string, _ string, opts *snapstate.RevisionOptions, _ int, _ snapstate.Flags, _ snapstate.DeviceContext) (*state.TaskSet, *snap.Info, error,
+		ctx context.Context, st *state.State, name string, components []string, blobDirectory string, revOpts snapstate.RevisionOptions, opts snapstate.Options) (*state.TaskSet, *snap.Info, error,
 	) {
 		expectedRev, ok := snapRevisions[name]
 		if !ok {
 			return nil, nil, fmt.Errorf("unexpected snap name %q", name)
 		}
 
-		c.Check(expectedRev, Equals, opts.Revision)
+		c.Check(expectedRev, Equals, revOpts.Revision)
 
-		tDownload := s.state.NewTask("mock-download", fmt.Sprintf("Download %s to track %s", name, opts.Channel))
+		tDownload := s.state.NewTask("mock-download", fmt.Sprintf("Download %s to track %s", name, revOpts.Channel))
 
 		si := &snap.SideInfo{
 			RealName: name,
-			Revision: opts.Revision,
+			Revision: revOpts.Revision,
 			SnapID:   fakeSnapID(name),
 		}
 		tDownload.Set("snap-setup", &snapstate.SnapSetup{
@@ -3654,7 +3654,7 @@ func (s *deviceMgrSystemsCreateSuite) TestDeviceManagerCreateRecoverySystemOffli
 	defer s.state.Unlock()
 
 	devicestate.MockSnapstateDownload(func(
-		_ context.Context, _ *state.State, name string, _ string, opts *snapstate.RevisionOptions, _ int, _ snapstate.Flags, _ snapstate.DeviceContext) (*state.TaskSet, *snap.Info, error,
+		ctx context.Context, st *state.State, name string, components []string, blobDirectory string, revOpts snapstate.RevisionOptions, opts snapstate.Options) (*state.TaskSet, *snap.Info, error,
 	) {
 		c.Errorf("snapstate.Download called unexpectedly")
 		return nil, nil, nil
@@ -3825,7 +3825,7 @@ func (s *deviceMgrSystemsCreateSuite) TestDeviceManagerCreateRecoverySystemValid
 	assertstatetest.AddMany(s.state, vsetAssert)
 
 	devicestate.MockSnapstateDownload(func(
-		_ context.Context, _ *state.State, name string, _ string, opts *snapstate.RevisionOptions, _ int, _ snapstate.Flags, _ snapstate.DeviceContext) (*state.TaskSet, *snap.Info, error,
+		ctx context.Context, st *state.State, name string, components []string, blobDirectory string, revOpts snapstate.RevisionOptions, opts snapstate.Options) (*state.TaskSet, *snap.Info, error,
 	) {
 		c.Errorf("snapstate.Download called unexpectedly")
 		return nil, nil, nil
@@ -4310,19 +4310,19 @@ func (s *deviceMgrSystemsCreateSuite) TestDeviceManagerCreateRecoverySystemValid
 	vset := vsetAssert.(*asserts.ValidationSet)
 
 	devicestate.MockSnapstateDownload(func(
-		_ context.Context, _ *state.State, name string, _ string, opts *snapstate.RevisionOptions, _ int, _ snapstate.Flags, _ snapstate.DeviceContext) (*state.TaskSet, *snap.Info, error,
+		ctx context.Context, st *state.State, name string, components []string, blobDirectory string, revOpts snapstate.RevisionOptions, opts snapstate.Options) (*state.TaskSet, *snap.Info, error,
 	) {
 		expectedRev, ok := snapRevisions[name]
 		if !ok {
 			return nil, nil, fmt.Errorf("unexpected snap name %q", name)
 		}
 
-		c.Check(expectedRev, Equals, opts.Revision)
+		c.Check(expectedRev, Equals, revOpts.Revision)
 
-		tDownload := s.state.NewTask("fake-download", fmt.Sprintf("Download %s to track %s", name, opts.Channel))
+		tDownload := s.state.NewTask("fake-download", fmt.Sprintf("Download %s to track %s", name, revOpts.Channel))
 		si := &snap.SideInfo{
 			RealName: name,
-			Revision: opts.Revision,
+			Revision: revOpts.Revision,
 			SnapID:   fakeSnapID(name),
 		}
 

overlord/devicestate/export_test.go

@@ -185,7 +185,7 @@ func MockSnapstateUpdatePathWithDeviceContext(f func(st *state.State, si *snap.S
 	return r
 }
 
-func MockSnapstateDownload(f func(ctx context.Context, st *state.State, name string, blobDirectory string, opts *snapstate.RevisionOptions, userID int, flags snapstate.Flags, deviceCtx snapstate.DeviceContext) (*state.TaskSet, *snap.Info, error)) (restore func()) {
+func MockSnapstateDownload(f func(ctx context.Context, st *state.State, name string, components []string, blobDirectory string, revOpts snapstate.RevisionOptions, opts snapstate.Options) (*state.TaskSet, *snap.Info, error)) (restore func()) {
 	r := testutil.Backup(&snapstateDownload)
 	snapstateDownload = f
 	return r

overlord/managers_test.go

@@ -13693,7 +13693,7 @@ func (s *mgrsSuite) testDownload(c *C, downloadDir string) {
 	st.Lock()
 	defer st.Unlock()
 
-	ts, info, err := snapstate.Download(context.TODO(), st, "foo", downloadDir, nil, 0, snapstate.Flags{}, nil)
+	ts, info, err := snapstate.Download(context.TODO(), st, "foo", nil, downloadDir, snapstate.RevisionOptions{}, snapstate.Options{})
 	c.Assert(err, IsNil)
 	chg := st.NewChange("download-snap", "...")
 	chg.AddAll(ts)
@@ -13753,9 +13753,9 @@ func (s *mgrsSuite) TestDownloadSpecificRevision(c *C) {
 	st.Lock()
 	defer st.Unlock()
 
-	ts, info, err := snapstate.Download(context.TODO(), st, "foo", "", &snapstate.RevisionOptions{
+	ts, info, err := snapstate.Download(context.TODO(), st, "foo", nil, "", snapstate.RevisionOptions{
 		Revision: snap.R(snapOldRev),
-	}, 0, snapstate.Flags{}, nil)
+	}, snapstate.Options{})
 	c.Assert(err, IsNil)
 	chg := st.NewChange("download-snap", "...")
 	chg.AddAll(ts)

overlord/snapstate/snapstate.go

@@ -1535,22 +1535,30 @@ func InstallPathWithDeviceContext(st *state.State, si *snap.SideInfo, path, name
 	return ts, nil
 }
 
-// Download returns a set of tasks for downloading a snap into the given
-// blobDirectory. If blobDirectory is empty, then dirs.SnapBlobDir is used. The
-// snap.Info for the snap that is downloaded is also returned. The tasks that
-// are returned will also download and validate the snap's assertion.
-// Prerequisites for the snap are not downloaded.
-func Download(ctx context.Context, st *state.State, name string, blobDirectory string, opts *RevisionOptions, userID int, flags Flags, deviceCtx DeviceContext) (*state.TaskSet, *snap.Info, error) {
-	if opts == nil {
-		opts = &RevisionOptions{}
+// Download returns a set of tasks for downloading a snap and components into
+// the given blobDirectory. If blobDirectory is empty, then dirs.SnapBlobDir is
+// used. The snap.Info for the snap that is downloaded is also returned. The
+// tasks that are returned will also download and validate the snap's and
+// components' assertions. Prerequisites for the snap are not downloaded.
+func Download(
+	ctx context.Context,
+	st *state.State,
+	name string,
+	components []string,
+	blobDirectory string,
+	revOpts RevisionOptions,
+	opts Options,
+) (*state.TaskSet, *snap.Info, error) {
+	if revOpts.CohortKey != "" && !revOpts.Revision.Unset() {
+		return nil, nil, errors.New("internal error: cannot specify revision and cohort")
 	}
 
-	if opts.CohortKey != "" && !opts.Revision.Unset() {
-		return nil, nil, errors.New("cannot specify revision and cohort")
+	if revOpts.Channel == "" {
+		revOpts.Channel = "stable"
 	}
 
-	if opts.Channel == "" {
-		opts.Channel = "stable"
+	if revOpts.ValidationSets == nil {
+		revOpts.ValidationSets = snapasserts.NewValidationSets()
 	}
 
 	var snapst SnapState
@@ -1563,35 +1571,40 @@ func Download(ctx context.Context, st *state.State, name string, blobDirectory s
 		return nil, nil, fmt.Errorf("invalid instance name: %v", err)
 	}
 
-	sar, err := downloadInfo(ctx, st, name, opts, userID, deviceCtx)
+	sars, err := sendDownloadActions(ctx, st, []StoreSnap{{
+		InstanceName: name,
+		Components:   components,
+		RevOpts:      revOpts,
+	}}, opts)
 	if err != nil {
 		return nil, nil, err
 	}
+	if len(sars) != 1 {
+		return nil, nil, fmt.Errorf("expected exactly one result from the store, got %d", len(sars))
+	}
 
+	sar := sars[0]
 	info := sar.Info
 
-	// if we are going to use the default download dir, and the same snap
-	// revision is already installed, then we should not overwrite the snap that
-	// is already in the dir.
-	if (blobDirectory == "" || blobDirectory == dirs.SnapBlobDir) && info.Revision == snapst.Current {
-		return nil, nil, &snap.AlreadyInstalledError{Snap: name}
+	if opts.PrereqTracker != nil {
+		opts.PrereqTracker.Add(info)
 	}
 
-	if flags.RequireTypeBase && info.Type() != snap.TypeBase && info.Type() != snap.TypeOS {
+	if opts.Flags.RequireTypeBase && info.Type() != snap.TypeBase && info.Type() != snap.TypeOS {
 		return nil, nil, fmt.Errorf("unexpected snap type %q, instead of 'base'", info.Type())
 	}
 
 	snapsup := &SnapSetup{
-		Channel:            opts.Channel,
+		Channel:            revOpts.Channel,
 		Base:               info.Base,
-		UserID:             userID,
-		Flags:              flags.ForSnapSetup(),
+		UserID:             opts.UserID,
+		Flags:              opts.Flags.ForSnapSetup(),
 		DownloadInfo:       &info.DownloadInfo,
 		SideInfo:           &info.SideInfo,
 		Type:               info.Type(),
 		Version:            info.Version,
 		InstanceKey:        info.InstanceKey,
-		CohortKey:          opts.CohortKey,
+		CohortKey:          revOpts.CohortKey,
 		ExpectedProvenance: info.SnapProvenance,
 		DownloadBlobDir:    blobDirectory,
 	}
@@ -1600,25 +1613,105 @@ func Download(ctx context.Context, st *state.State, name string, blobDirectory s
 		snapsup.Channel = sar.RedirectChannel
 	}
 
+	compsups, err := componentTargetsFromActionResult("download", sar, components)
+	if err != nil {
+		return nil, nil, fmt.Errorf("cannot extract components from snap resources: %w", err)
+	}
+
+	for i := range compsups {
+		compsups[i].DownloadBlobDir = blobDirectory
+	}
+
+	if err := checkSnapActionAgainstValidationSets(sar, compsups, "download", revOpts.ValidationSets); err != nil {
+		return nil, nil, err
+	}
+
 	toDownloadTo := filepath.Dir(snapsup.MountFile())
+
+	// TODO:COMPS: support checking for available space for components
 	if err := checkDiskSpaceDownload([]minimalInstallInfo{installSnapInfo{info}}, toDownloadTo); err != nil {
 		return nil, nil, err
 	}
 
+	snapAlreadyInstalled := (blobDirectory == "" || blobDirectory == dirs.SnapBlobDir) &&
+		snapst.Sequence.LastIndex(info.Revision) != -1
+	componentAlreadyInstalled := make(map[string]bool, len(compsups))
+	allInstalled := snapAlreadyInstalled
+	for _, c := range compsups {
+		componentAlreadyInstalled[c.ComponentName()] = (blobDirectory == "" || blobDirectory == dirs.SnapBlobDir) &&
+			snapst.Sequence.IsComponentRevPresent(c.CompSideInfo)
+		allInstalled = allInstalled && componentAlreadyInstalled[c.ComponentName()]
+	}
+
+	if allInstalled {
+		return nil, nil, &snap.AlreadyInstalledError{Snap: name}
+	}
+
+	ts := state.NewTaskSet()
+	var snapsupTask, prev *state.Task
+	addTask := func(t *state.Task) {
+		ts.AddTask(t)
+		if prev == nil {
+			t.Set("snap-setup", snapsup)
+			snapsupTask = t
+			ts.MarkEdge(t, BeginEdge)
+		} else {
+			t.WaitFor(prev)
+			t.Set("snap-setup-task", snapsupTask.ID())
+		}
+		prev = t
+	}
+
 	revisionStr := fmt.Sprintf(" (%s)", snapsup.Revision())
 
-	download := st.NewTask("download-snap", fmt.Sprintf(i18n.G("Download snap %q%s from channel %q"), snapsup.InstanceName(), revisionStr, snapsup.Channel))
-	download.Set("snap-setup", snapsup)
+	if !snapAlreadyInstalled {
+		download := st.NewTask("download-snap", fmt.Sprintf(i18n.G("Download snap %q%s from channel %q"), snapsup.InstanceName(), revisionStr, snapsup.Channel))
+		addTask(download)
+	} else {
+		// validate-snap expects this to be set, and since we know that this
+		// already should exist, we can set it here
+		snapsup.SnapPath = snapsup.MountFile()
+	}
+
+	validate := st.NewTask("validate-snap", fmt.Sprintf(i18n.G("Fetch and check assertions for snap %q%s"), snapsup.InstanceName(), revisionStr))
+	addTask(validate)
 
-	checkAsserts := st.NewTask("validate-snap", fmt.Sprintf(i18n.G("Fetch and check assertions for snap %q%s"), snapsup.InstanceName(), revisionStr))
-	checkAsserts.Set("snap-setup-task", download.ID())
-	checkAsserts.WaitFor(download)
+	compsupIDs := make([]string, 0, len(compsups))
+	for _, c := range compsups {
+		rev := fmt.Sprintf(" (%s)", c.CompSideInfo.Revision)
 
-	installSet := state.NewTaskSet(download, checkAsserts)
-	installSet.MarkEdge(download, BeginEdge)
-	installSet.MarkEdge(checkAsserts, LastBeforeLocalModificationsEdge)
+		var compsupTaskID string
+		if !componentAlreadyInstalled[c.ComponentName()] {
+			download := st.NewTask("download-component", fmt.Sprintf(i18n.G("Download component %q%s"), c.ComponentName(), rev))
+			download.Set("component-setup", c)
+			addTask(download)
+			compsupTaskID = download.ID()
+		}
+
+		// even if the component itself is already installed, it might not have
+		// been installed with the same snap revision. in that case,
+		// validate-component will fetch new assertions from the store.
+		validate := st.NewTask("validate-component", fmt.Sprintf(
+			i18n.G("Fetch and check assertions for component %q%s"), c.ComponentName(), rev),
+		)
+		if compsupTaskID == "" {
+			validate.Set("component-setup", c)
+			compsupTaskID = validate.ID()
+		} else {
+			validate.Set("component-setup-task", compsupTaskID)
+		}
+		addTask(validate)
 
-	return installSet, info, nil
+		compsupIDs = append(compsupIDs, compsupTaskID)
+	}
+
+	snapsupTask.Set("component-setup-tasks", compsupIDs)
+
+	// since nothing in this function does any "local" modifications, we just
+	// set this edge on the last task in the chain
+	ts.MarkEdge(prev, LastBeforeLocalModificationsEdge)
+
+	return ts, info, nil
 }
 
 func validatedInfoFromPathAndSideInfo(instanceName string, path string, si *snap.SideInfo) (*snap.Info, error) {