Allow to import an image for the default platform only.

Add `all-platforms` option to `ctr images import`.

Signed-off-by: Aldo Culquicondor <acondor@google.com>

import.go

@@ -25,14 +25,16 @@ import (
 	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/images"
 	"github.com/containerd/containerd/images/archive"
+	"github.com/containerd/containerd/platforms"
 	digest "github.com/opencontainers/go-digest"
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 )
 
 type importOpts struct {
-	indexName string
-	imageRefT func(string) string
-	dgstRefT  func(digest.Digest) string
+	indexName    string
+	imageRefT    func(string) string
+	dgstRefT     func(digest.Digest) string
+	allPlatforms bool
 }
 
 // ImportOpt allows the caller to specify import specific options
@@ -64,6 +66,14 @@ func WithIndexName(name string) ImportOpt {
 	}
 }
 
+// WithAllPlatforms is used to import content for all platforms.
+func WithAllPlatforms(allPlatforms bool) ImportOpt {
+	return func(c *importOpts) error {
+		c.allPlatforms = allPlatforms
+		return nil
+	}
+}
+
 // Import imports an image from a Tar stream using reader.
 // Caller needs to specify importer. Future version may use oci.v1 as the default.
 // Note that unreferrenced blobs may be imported to the content store as well.
@@ -98,6 +108,10 @@ func (c *Client) Import(ctx context.Context, reader io.Reader, opts ...ImportOpt
 			Target: index,
 		})
 	}
+	var platformMatcher = platforms.All
+	if !iopts.allPlatforms {
+		platformMatcher = platforms.Default()
+	}
 
 	var handler images.HandlerFunc = func(ctx context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
 		// Only save images at top level
@@ -141,6 +155,7 @@ func (c *Client) Import(ctx context.Context, reader io.Reader, opts ...ImportOpt
 		return idx.Manifests, nil
 	}
 
+	handler = images.FilterPlatforms(handler, platformMatcher)
 	handler = images.SetChildrenLabels(cs, handler)
 	if err := images.Walk(ctx, handler, index); err != nil {
 		return nil, err