Do not process attestation manifests

Some docker-built containers may have a so-called attestation manifest.
These are not meant to be processed as normal images, but instead,
will have an arch and OS of "unknown".

Preflight will now ignore any image listed in a manifest that has
arch and OS as "unknown".

Signed-off-by: Brad P. Crochet <brad@redhat.com>

cmd/preflight/cmd/check_container.go

@@ -432,6 +432,10 @@ func platformsToBeProcessed(cmd *cobra.Command, cfg *runtime.Config) ([]string,
 				// The user selected a platform. If this isn't it, continue.
 				continue
 			}
+			if img.Platform.Architecture == "unknown" && img.Platform.OS == "unknown" {
+				// This must be an attestation manifest. Skip it.
+				continue
+			}
 			containerImagePlatforms = append(containerImagePlatforms, img.Platform.Architecture)
 		}
 		if platformChanged && len(containerImagePlatforms) == 0 {

cmd/preflight/cmd/check_container_test.go

@@ -35,6 +35,35 @@ import (
 	"github.com/onsi/gomega/types"
 )
 
+func createPlatformImage(arch string, addlLayers int) cranev1.Image {
+	// Expected values.
+	img, err := random.Image(1024, 5)
+	Expect(err).ToNot(HaveOccurred())
+
+	for i := 0; i < addlLayers; i++ {
+		newLayer, err := random.Layer(1024, cranev1types.OCILayer)
+		Expect(err).ToNot(HaveOccurred())
+		img, err = mutate.AppendLayers(img, newLayer)
+		Expect(err).ToNot(HaveOccurred())
+	}
+
+	cfgFile, err := img.ConfigFile()
+	Expect(err).ToNot(HaveOccurred())
+
+	cfgFile.Architecture = arch
+
+	cfgImg, err := mutate.ConfigFile(img, cfgFile)
+	Expect(err).ToNot(HaveOccurred())
+
+	return cfgImg
+}
+
+func createImageAndPush(src, arch string, addlLayers int) string {
+	img := createPlatformImage(arch, addlLayers)
+	Expect(crane.Push(img, src)).To(Succeed())
+	return src
+}
+
 var _ = Describe("Check Container Command", func() {
 	var src string
 	var manifestListSrc string
@@ -54,46 +83,16 @@ var _ = Describe("Check Container Command", func() {
 		Expect(err).ToNot(HaveOccurred())
 
 		src = fmt.Sprintf("%s/test/crane", u.Host)
-		manifests["image"] = src
-
-		// Expected values.
-		img, err := random.Image(1024, 5)
-		Expect(err).ToNot(HaveOccurred())
-
-		cfgFile, err := img.ConfigFile()
-		Expect(err).ToNot(HaveOccurred())
-
-		cfgFile.Architecture = "amd64"
-
-		cfgImg, err := mutate.ConfigFile(img, cfgFile)
-		Expect(err).ToNot(HaveOccurred())
-
-		err = crane.Push(cfgImg, src)
-		Expect(err).ToNot(HaveOccurred())
+		manifests["image"] = createImageAndPush(src, "amd64", 0)
 
 		srcppc = fmt.Sprintf("%s/test/craneppc", u.Host)
-		manifests["imageppc"] = srcppc
-
-		newLayer, err := random.Layer(1024, cranev1types.OCILayer)
-		Expect(err).ToNot(HaveOccurred())
-
-		ppcImg, err := mutate.AppendLayers(img, newLayer)
-		Expect(err).ToNot(HaveOccurred())
-
-		ppcCfgFile, err := ppcImg.ConfigFile()
-		Expect(err).ToNot(HaveOccurred())
+		manifests["imageppc"] = createImageAndPush(srcppc, "ppc64le", 1)
 
-		ppcCfgFile.Architecture = "ppc64le"
-
-		ppcCfgImg, err := mutate.ConfigFile(ppcImg, ppcCfgFile)
-		Expect(err).ToNot(HaveOccurred())
-
-		Expect(crane.Push(ppcCfgImg, srcppc)).To(Succeed())
-
-		platforms := [4]string{"amd64", "arm64", "ppc64le", "s390x"}
 		manifestListSrc = fmt.Sprintf("%s/test/cranelist", u.Host)
 		manifests["index"] = manifestListSrc
-		lst, err := random.Index(1024, 5, int64(len(platforms)))
+
+		platforms := [4]string{"amd64", "arm64", "ppc64le", "s390x"}
+		lst, err := random.Index(1024, 5, int64(len(platforms)+1))
 		Expect(err).ToNot(HaveOccurred())
 
 		ref, err := name.ParseReference(manifestListSrc)
@@ -104,6 +103,11 @@ var _ = Describe("Check Container Command", func() {
 
 		for i, manifest := range m.Manifests {
 			switch {
+			case i == len(platforms):
+				m.Manifests[i].Platform = &cranev1.Platform{
+					Architecture: "unknown",
+					OS:           "unknown",
+				}
 			case manifest.MediaType.IsImage():
 				m.Manifests[i].Platform = &cranev1.Platform{
 					Architecture: platforms[i],