remove always false parameter

Simplify allocDir.Build() function to avoid depending on client/structs,
and remove a parameter that's always set to `false`.

The motivation here is to avoid a dependency cycle between
drivers/cstructs and alloc_dir.

client/allocdir/alloc_dir_test.go

@@ -14,7 +14,6 @@ import (
 	"syscall"
 	"testing"
 
-	cstructs "github.com/hashicorp/nomad/client/structs"
 	"github.com/hashicorp/nomad/helper/testlog"
 	"github.com/hashicorp/nomad/nomad/structs"
 	"github.com/stretchr/testify/require"
@@ -112,11 +111,11 @@ func TestAllocDir_MountSharedAlloc(t *testing.T) {
 
 	// Build 2 task dirs
 	td1 := d.NewTaskDir(t1.Name)
-	if err := td1.Build(false, nil, cstructs.FSIsolationChroot); err != nil {
+	if err := td1.Build(true, nil); err != nil {
 		t.Fatalf("error build task=%q dir: %v", t1.Name, err)
 	}
 	td2 := d.NewTaskDir(t2.Name)
-	if err := td2.Build(false, nil, cstructs.FSIsolationChroot); err != nil {
+	if err := td2.Build(true, nil); err != nil {
 		t.Fatalf("error build task=%q dir: %v", t2.Name, err)
 	}
 
@@ -157,11 +156,11 @@ func TestAllocDir_Snapshot(t *testing.T) {
 
 	// Build 2 task dirs
 	td1 := d.NewTaskDir(t1.Name)
-	if err := td1.Build(false, nil, cstructs.FSIsolationImage); err != nil {
+	if err := td1.Build(false, nil); err != nil {
 		t.Fatalf("error build task=%q dir: %v", t1.Name, err)
 	}
 	td2 := d.NewTaskDir(t2.Name)
-	if err := td2.Build(false, nil, cstructs.FSIsolationImage); err != nil {
+	if err := td2.Build(false, nil); err != nil {
 		t.Fatalf("error build task=%q dir: %v", t2.Name, err)
 	}
 
@@ -249,7 +248,7 @@ func TestAllocDir_Move(t *testing.T) {
 	defer d2.Destroy()
 
 	td1 := d1.NewTaskDir(t1.Name)
-	if err := td1.Build(false, nil, cstructs.FSIsolationImage); err != nil {
+	if err := td1.Build(false, nil); err != nil {
 		t.Fatalf("TaskDir.Build() faild: %v", err)
 	}
 
@@ -345,7 +344,7 @@ func TestAllocDir_ReadAt_SecretDir(t *testing.T) {
 	defer d.Destroy()
 
 	td := d.NewTaskDir(t1.Name)
-	if err := td.Build(false, nil, cstructs.FSIsolationImage); err != nil {
+	if err := td.Build(false, nil); err != nil {
 		t.Fatalf("TaskDir.Build() failed: %v", err)
 	}
 

client/allocdir/task_dir.go

@@ -7,7 +7,6 @@ import (
 	"path/filepath"
 
 	hclog "github.com/hashicorp/go-hclog"
-	cstructs "github.com/hashicorp/nomad/client/structs"
 )
 
 // TaskDir contains all of the paths relevant to a task. All paths are on the
@@ -75,7 +74,7 @@ func (t *TaskDir) Copy() *TaskDir {
 // Build default directories and permissions in a task directory. chrootCreated
 // allows skipping chroot creation if the caller knows it has already been
 // done.
-func (t *TaskDir) Build(chrootCreated bool, chroot map[string]string, fsi cstructs.FSIsolation) error {
+func (t *TaskDir) Build(createChroot bool, chroot map[string]string) error {
 	if err := os.MkdirAll(t.Dir, 0777); err != nil {
 		return err
 	}
@@ -110,7 +109,7 @@ func (t *TaskDir) Build(chrootCreated bool, chroot map[string]string, fsi cstruc
 	// Image based isolation will bind the shared alloc dir in the driver.
 	// If there's no isolation the task will use the host path to the
 	// shared alloc dir.
-	if fsi == cstructs.FSIsolationChroot {
+	if createChroot {
 		// If the path doesn't exist OR it exists and is empty, link it
 		empty, _ := pathEmpty(t.SharedTaskDir)
 		if !pathExists(t.SharedTaskDir) || empty {
@@ -130,8 +129,8 @@ func (t *TaskDir) Build(chrootCreated bool, chroot map[string]string, fsi cstruc
 	}
 
 	// Build chroot if chroot filesystem isolation is going to be used
-	if fsi == cstructs.FSIsolationChroot {
-		if err := t.buildChroot(chrootCreated, chroot); err != nil {
+	if createChroot {
+		if err := t.buildChroot(chroot); err != nil {
 			return err
 		}
 	}
@@ -142,15 +141,9 @@ func (t *TaskDir) Build(chrootCreated bool, chroot map[string]string, fsi cstruc
 // buildChroot takes a mapping of absolute directory or file paths on the host
 // to their intended, relative location within the task directory. This
 // attempts hardlink and then defaults to copying. If the path exists on the
-// host and can't be embedded an error is returned. If chrootCreated is true
-// skip expensive embedding operations and only ephemeral operations (eg
-// mounting /dev) are done.
-func (t *TaskDir) buildChroot(chrootCreated bool, entries map[string]string) error {
-	if !chrootCreated {
-		// Link/copy chroot entries
-		return t.embedDirs(entries)
-	}
-	return nil
+// host and can't be embedded an error is returned.
+func (t *TaskDir) buildChroot(entries map[string]string) error {
+	return t.embedDirs(entries)
 }
 
 func (t *TaskDir) embedDirs(entries map[string]string) error {

client/allocdir/task_dir_test.go

@@ -6,7 +6,6 @@ import (
 	"path/filepath"
 	"testing"
 
-	cstructs "github.com/hashicorp/nomad/client/structs"
 	"github.com/hashicorp/nomad/helper/testlog"
 )
 
@@ -104,7 +103,7 @@ func TestTaskDir_NonRoot_Image(t *testing.T) {
 		t.Fatalf("Build() failed: %v", err)
 	}
 
-	if err := td.Build(false, nil, cstructs.FSIsolationImage); err != nil {
+	if err := td.Build(false, nil); err != nil {
 		t.Fatalf("TaskDir.Build failed: %v", err)
 	}
 }
@@ -127,7 +126,7 @@ func TestTaskDir_NonRoot(t *testing.T) {
 		t.Fatalf("Build() failed: %v", err)
 	}
 
-	if err := td.Build(false, nil, cstructs.FSIsolationNone); err != nil {
+	if err := td.Build(false, nil); err != nil {
 		t.Fatalf("TaskDir.Build failed: %v", err)
 	}
 

client/allocrunner/taskrunner/task_dir_hook.go

@@ -44,7 +44,7 @@ func (h *taskDirHook) Prestart(ctx context.Context, req *interfaces.TaskPrestart
 
 	// Build the task directory structure
 	fsi := h.runner.driverCapabilities.FSIsolation
-	err := h.runner.taskDir.Build(false, chroot, fsi)
+	err := h.runner.taskDir.Build(fsi == cstructs.FSIsolationChroot, chroot)
 	if err != nil {
 		return err
 	}