Allow switching manifest packing version and update README

README.md

@@ -5,6 +5,11 @@
 The policy CLI is a tool for building, versioning and publishing your authorization policies.
 It uses OCI standards to manage artifacts, and the [Open Policy Agent (OPA)](https://github.com/open-policy-agent/opa) to compile and run.
 
+
+  > ***As of version v0.2.4 we use the OCI Image Manifest defined in image-spec v1.1.0-rc4 when building policy images.*** This can cause issues when trying to push the image to some registries (ex. Amazon ECR)
+  
+  > To set the CLI to build the policy image using the the OCI Image Manifest defined in image-spec v1.0.2 you can set the *USE_PACK_MANIFEST_1_0* environment variable to true.
+
 ---
 
 [![Go Report Card](https://goreportcard.com/badge/github.com/opcr-io/policy?)](https://goreportcard.com/report/github.com/opcr-io/policy)

pkg/app/build.go

@@ -200,7 +200,12 @@ func (c *PolicyApp) createImage(ociStore *orasoci.Store, tarball string, annotat
 		return descriptor, err
 	}
 
-	manifestDesc, err := oras.PackManifest(c.Context, ociStore, oras.PackManifestVersion1_1_RC4, ocispec.MediaTypeImageManifest, oras.PackManifestOptions{Layers: []ocispec.Descriptor{descriptor}, ConfigDescriptor: &configDesc, ManifestAnnotations: descriptor.Annotations})
+	packVersion := oras.PackManifestVersion1_1_RC4
+	if os.Getenv("USE_PACK_MANIFEST_1_0") == "true" {
+		packVersion = oras.PackManifestVersion1_0
+	}
+
+	manifestDesc, err := oras.PackManifest(c.Context, ociStore, packVersion, ocispec.MediaTypeImageManifest, oras.PackManifestOptions{Layers: []ocispec.Descriptor{descriptor}, ConfigDescriptor: &configDesc, ManifestAnnotations: descriptor.Annotations})
 	if err != nil {
 		return manifestDesc, err
 	}