Support persistent home directory

This commit allows the `/home/user/` directory in workspaces to  persist if  persistent storage is enabled
(through the use of the 'per-user' ('common') or 'per-workspace' storage class).

To enable this feature, modify the DWOC and set `config.workspace.persistUserHome.enabled` to `true`.

When enabled, a Devfile volume named `persistentHome` will be added to DevWorkspaces. All DevWorkspace container
components will mount the `persistentHome` volume at `/home/user/`. If a container component of a DevWorkspace already
mounts to `/home/user/`, the DWO-provisioned `persistentHome` volume will not be added to the DevWorkspace.

Fix #1097

Signed-off-by: Andrew Obuchowicz <aobuchow@redhat.com>

controllers/workspace/devworkspace_controller.go

@@ -34,6 +34,7 @@ import (
 	containerlib "github.com/devfile/devworkspace-operator/pkg/library/container"
 	"github.com/devfile/devworkspace-operator/pkg/library/env"
 	"github.com/devfile/devworkspace-operator/pkg/library/flatten"
+	"github.com/devfile/devworkspace-operator/pkg/library/home"
 	kubesync "github.com/devfile/devworkspace-operator/pkg/library/kubernetes"
 	"github.com/devfile/devworkspace-operator/pkg/library/projects"
 	"github.com/devfile/devworkspace-operator/pkg/library/status"
@@ -289,6 +290,15 @@ func (r *DevWorkspaceReconciler) Reconcile(ctx context.Context, req ctrl.Request
 		return r.failWorkspace(workspace, fmt.Sprintf("Error provisioning storage: %s", err), metrics.ReasonBadRequest, reqLogger, &reconcileStatus), nil
 	}
 
+	if home.NeedsPersistentHomeDirectory(workspace) {
+		workspaceWithHomeVolume, err := home.AddPersistentHomeVolume(workspace)
+		if err != nil {
+			reconcileStatus.addWarning(fmt.Sprintf("Info: default persistentHome volume is not being used: %s", err.Error()))
+		} else {
+			workspace.Spec.Template = *workspaceWithHomeVolume
+		}
+	}
+
 	// Set finalizer on DevWorkspace if necessary
 	// Note: we need to check the flattened workspace to see if a finalizer is needed, as plugins could require storage
 	if storageProvisioner.NeedsStorage(&workspace.Spec.Template) && !controllerutil.ContainsFinalizer(clusterWorkspace, constants.StorageCleanupFinalizer) {

pkg/constants/constants.go

@@ -37,6 +37,10 @@ var (
 const (
 	DefaultProjectsSourcesRoot = "/projects"
 
+	HomeUserDirectory = "/home/user/"
+
+	HomeVolumeName = "persistentHome"
+
 	ServiceAccount = "devworkspace"
 
 	SidecarDefaultMemoryLimit   = "128M"

pkg/library/home/persistentHome.go

@@ -0,0 +1,82 @@
+//
+// Copyright (c) 2019-2023 Red Hat, Inc.
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+package home
+
+import (
+	"fmt"
+
+	"github.com/devfile/api/v2/pkg/apis/workspaces/v1alpha2"
+	devfilevalidation "github.com/devfile/api/v2/pkg/validation"
+	"k8s.io/utils/pointer"
+
+	"github.com/devfile/devworkspace-operator/pkg/common"
+	"github.com/devfile/devworkspace-operator/pkg/constants"
+)
+
+// Returns a modified copy of the given DevWorkspace's Template Spec which contains an additional
+// Devfile volume 'persistentHome' that is mounted  to `/home/user/` for every container component defined in the DevWorkspace.
+// An error is returned if the addition of the 'persistentHome' volume would result
+// in an invalid DevWorkspace.
+func AddPersistentHomeVolume(workspace *common.DevWorkspaceWithConfig) (*v1alpha2.DevWorkspaceTemplateSpec, error) {
+	dwTemplateSpecCopy := workspace.Spec.Template.DeepCopy()
+	homeVolume := v1alpha2.Component{
+		Name: constants.HomeVolumeName,
+		ComponentUnion: v1alpha2.ComponentUnion{
+			Volume: &v1alpha2.VolumeComponent{},
+		},
+	}
+	homeVolumeMount := v1alpha2.VolumeMount{
+		Name: constants.HomeVolumeName,
+		Path: constants.HomeUserDirectory,
+	}
+
+	dwTemplateSpecCopy.Components = append(dwTemplateSpecCopy.Components, homeVolume)
+	for _, component := range dwTemplateSpecCopy.Components {
+		if component.Container == nil {
+			continue
+		}
+		component.Container.VolumeMounts = append(component.Container.VolumeMounts, homeVolumeMount)
+	}
+
+	err := devfilevalidation.ValidateComponents(dwTemplateSpecCopy.Components)
+	if err != nil {
+		return nil, fmt.Errorf("addition of %s volume would render DevWorkspace invalid: %w", constants.HomeVolumeName, err)
+	}
+
+	return dwTemplateSpecCopy, nil
+}
+
+// Returns true if `persistUserHome` is enabled in the DevWorkspaceOperatorConfig
+// and none of the container components in the DevWorkspace mount a volume to `/home/user/`.
+// Returns false otherwise.
+func NeedsPersistentHomeDirectory(workspace *common.DevWorkspaceWithConfig) bool {
+	if !pointer.BoolDeref(workspace.Config.Workspace.PersistUserHome.Enabled, false) {
+		return false
+	}
+	for _, component := range workspace.Spec.Template.Components {
+		if component.Container == nil {
+			continue
+		}
+		for _, volumeMount := range component.Container.VolumeMounts {
+			if volumeMount.Path == constants.HomeUserDirectory {
+				// If a volume is already being mounted to /home/user/, it takes precedence
+				// over the DWO-provisioned home directory volume.
+				return false
+			}
+		}
+	}
+	return true
+}

pkg/provision/workspace/persistentHome_test.go

@@ -0,0 +1,105 @@
+//
+// Copyright (c) 2019-2023 Red Hat, Inc.
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+package workspace
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	dw "github.com/devfile/api/v2/pkg/apis/workspaces/v1alpha2"
+	"github.com/devfile/devworkspace-operator/apis/controller/v1alpha1"
+	"github.com/devfile/devworkspace-operator/pkg/common"
+	"github.com/google/go-cmp/cmp"
+	"sigs.k8s.io/yaml"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type testCase struct {
+	Name   string     `json:"name,omitempty"`
+	Input  testInput  `json:"input,omitempty"`
+	Output testOutput `json:"output,omitempty"`
+}
+
+type testInput struct {
+	DevWorkspaceID string                          `json:"devworkspaceId,omitempty"`
+	Workspace      *dw.DevWorkspaceTemplateSpec    `json:"workspace,omitempty"`
+	Config         *v1alpha1.OperatorConfiguration `json:"config,omitempty"`
+}
+
+type testOutput struct {
+	Workspace *dw.DevWorkspaceTemplateSpec `json:"workspace,omitempty"`
+}
+
+func loadTestCaseOrPanic(t *testing.T, testFilepath string) testCase {
+	bytes, err := os.ReadFile(testFilepath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var test testCase
+	if err := yaml.Unmarshal(bytes, &test); err != nil {
+		t.Fatal(err)
+	}
+	return test
+}
+
+func loadAllTestCasesOrPanic(t *testing.T, fromDir string) []testCase {
+	files, err := os.ReadDir(fromDir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var tests []testCase
+	for _, file := range files {
+		if file.IsDir() {
+			continue
+		}
+		tests = append(tests, loadTestCaseOrPanic(t, filepath.Join(fromDir, file.Name())))
+	}
+	return tests
+}
+
+func getDevWorkspaceWithConfig(input testInput) *common.DevWorkspaceWithConfig {
+	return &common.DevWorkspaceWithConfig{
+		DevWorkspace: &dw.DevWorkspace{
+			Spec: dw.DevWorkspaceSpec{
+				Template: *input.Workspace,
+			},
+		},
+		Config: input.Config,
+	}
+}
+
+func TestPersistentHomeVolume(t *testing.T) {
+	tests := loadAllTestCasesOrPanic(t, "testdata/persistent-home")
+	for _, tt := range tests {
+		t.Run(tt.Name, func(t *testing.T) {
+			// sanity check that file is read correctly.
+			assert.NotNil(t, tt.Input.Workspace, "Input does not define workspace")
+			assert.NotNil(t, tt.Input.Config, "Input does not define a config")
+			workspace := getDevWorkspaceWithConfig(tt.Input)
+
+			if NeedsPersistentHomeDirectory(workspace) {
+				AddHomeVolume(&workspace.Spec.Template)
+			}
+
+			assert.Equal(t, tt.Output.Workspace.DevWorkspaceTemplateSpecContent, workspace.Spec.Template.DevWorkspaceTemplateSpecContent,
+				"DevWorkspace Template Spec should match expected output: Diff: %s",
+				cmp.Diff(tt.Output.Workspace.DevWorkspaceTemplateSpecContent, workspace.Spec.Template.DevWorkspaceTemplateSpecContent))
+		})
+	}
+
+}