Add basic spec and mounts for Darwin

Signed-off-by: Maksym Pavlenko <pavlenko.maksym@gmail.com>

oci/spec.go

@@ -21,11 +21,11 @@ import (
 	"path/filepath"
 	"runtime"
 
-	"github.com/containerd/containerd/namespaces"
-	"github.com/containerd/containerd/platforms"
+	"github.com/opencontainers/runtime-spec/specs-go"
 
 	"github.com/containerd/containerd/containers"
-	specs "github.com/opencontainers/runtime-spec/specs-go"
+	"github.com/containerd/containerd/namespaces"
+	"github.com/containerd/containerd/platforms"
 )
 
 const (
@@ -66,15 +66,19 @@ func generateDefaultSpecWithPlatform(ctx context.Context, platform, id string, s
 		return err
 	}
 
-	if plat.OS == "windows" {
+	switch plat.OS {
+	case "windows":
 		err = populateDefaultWindowsSpec(ctx, s, id)
-	} else {
+	case "darwin":
+		err = populateDefaultDarwinSpec(s)
+	default:
 		err = populateDefaultUnixSpec(ctx, s, id)
 		if err == nil && runtime.GOOS == "windows" {
 			// To run LCOW we have a Linux and Windows section. Add an empty one now.
 			s.Windows = &specs.Windows{}
 		}
 	}
+
 	return err
 }
 
@@ -207,3 +211,12 @@ func populateDefaultWindowsSpec(ctx context.Context, s *Spec, id string) error {
 	}
 	return nil
 }
+
+func populateDefaultDarwinSpec(s *Spec) error {
+	*s = Spec{
+		Version: specs.Version,
+		Root:    &specs.Root{},
+		Process: &specs.Process{Cwd: "/"},
+	}
+	return nil
+}

oci/spec_opts_test.go

@@ -30,17 +30,16 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/opencontainers/go-digest"
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/opencontainers/runtime-spec/specs-go"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
+	"github.com/containerd/containerd/containers"
 	"github.com/containerd/containerd/content"
 	"github.com/containerd/containerd/errdefs"
-	"github.com/opencontainers/go-digest"
-	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
-
-	"github.com/containerd/containerd/containers"
 	"github.com/containerd/containerd/namespaces"
-	"github.com/opencontainers/runtime-spec/specs-go"
 )
 
 type blob []byte
@@ -302,13 +301,20 @@ func TestWithDefaultSpec(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	var expected Spec
-	var err error
-	if runtime.GOOS == "windows" {
+	var (
+		expected Spec
+		err      error
+	)
+
+	switch runtime.GOOS {
+	case "windows":
 		err = populateDefaultWindowsSpec(ctx, &expected, c.ID)
-	} else {
+	case "darwin":
+		err = populateDefaultDarwinSpec(&expected)
+	default:
 		err = populateDefaultUnixSpec(ctx, &expected, c.ID)
 	}
+
 	if err != nil {
 		t.Fatal(err)
 	}

oci/spec_test.go

@@ -21,10 +21,11 @@ import (
 	"runtime"
 	"testing"
 
+	"github.com/opencontainers/runtime-spec/specs-go"
+
 	"github.com/containerd/containerd/containers"
 	"github.com/containerd/containerd/namespaces"
 	"github.com/containerd/containerd/pkg/testutil"
-	specs "github.com/opencontainers/runtime-spec/specs-go"
 )
 
 func TestGenerateSpec(t *testing.T) {
@@ -39,7 +40,7 @@ func TestGenerateSpec(t *testing.T) {
 		t.Fatal("GenerateSpec() returns a nil spec")
 	}
 
-	if runtime.GOOS != "windows" {
+	if runtime.GOOS == "linux" {
 		// check for matching caps
 		defaults := defaultUnixCaps()
 		for _, cl := range [][]string{
@@ -61,9 +62,9 @@ func TestGenerateSpec(t *testing.T) {
 				t.Errorf("ns at %d does not match set %q != %q", i, defaultNS[i], ns)
 			}
 		}
-	} else {
+	} else if runtime.GOOS == "windows" {
 		if s.Windows == nil {
-			t.Fatal("Windows section of spec not filled in on Windows platform")
+			t.Fatal("Windows section of spec not filled in for Windows spec")
 		}
 	}
 
@@ -122,7 +123,7 @@ func TestSpecWithTTY(t *testing.T) {
 	if !s.Process.Terminal {
 		t.Error("terminal net set WithTTY()")
 	}
-	if runtime.GOOS != "windows" {
+	if runtime.GOOS == "linux" {
 		v := s.Process.Env[len(s.Process.Env)-1]
 		if v != "TERM=xterm" {
 			t.Errorf("xterm not set in env for TTY")