schema: Add schema and test for artifact manifest

Signed-off-by: Sajay Antony <sajaya@microsoft.com>

schema/artifact-manifest-schema.json

@@ -0,0 +1,29 @@
+{
+  "description": "OpenContainer Artifact Manifest Specification",
+  "$schema": "http://json-schema.org/draft-04/schema#",
+  "id": "https://opencontainers.org/schema/artifact",
+  "type": "object",
+  "properties": {
+    "mediaType": {
+      "description": "the mediatype of the referenced object",
+      "$ref": "defs-descriptor.json#/definitions/mediaType"
+    },
+    "artifactType": {
+      "description": "The IANA mediatype of the referenced objects properties",
+      "$ref": "defs-descriptor.json#/definitions/mediaType"
+    }, 
+    "blobs": {
+      "type": "array",
+      "items": {
+        "$ref": "content-descriptor.json"
+      }
+    },
+    "subject": {
+      "$ref": "content-descriptor.json"
+    },
+    "annotations": {
+      "id": "https://opencontainers.org/schema/image/manifest/annotations",
+      "$ref": "defs-descriptor.json#/definitions/annotations"
+    }
+  }
+}

schema/artifact_test.go

@@ -0,0 +1,148 @@
+// Copyright 2016 The Linux Foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package schema_test
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/opencontainers/image-spec/schema"
+)
+
+func TestArtifact(t *testing.T) {
+	for i, tt := range []struct {
+		manifest string
+		fail     bool
+	}{
+		// expected failure: mediaType does not match pattern
+		{
+			manifest: `
+{
+  "mediaType": "invalid",
+  "artifactType": "application/example",
+  "blobs": [
+    {
+      "mediaType": "application/vnd.oci.image.layer.v1.tar+gzip",
+      "size": 148,
+      "digest": "sha256:c57089565e894899735d458f0fd4bb17a0f1e0df8d72da392b85c9b35ee777cd"
+    }
+  ]
+}
+`,
+			fail: true,
+		},
+
+		// expected failure: invalid artifact mediaType
+		{
+			manifest: `
+{
+  "mediaType": "application/vnd.oci.artifact.manifest.v1+json",
+  "artifactType": "invalid",
+  "blobs": [
+    {
+      "mediaType": "application/vnd.oci.image.layer.v1.tar+gzip",
+      "size": "148",
+      "digest": "sha256:c57089565e894899735d458f0fd4bb17a0f1e0df8d72da392b85c9b35ee777cd"
+    }
+  ]
+}
+`,
+			fail: true,
+		},
+
+		// expected failure: blob[0].size is a string, expected integer
+		{
+			manifest: `
+{
+  "mediaType": "application/vnd.oci.artifact.manifest.v1+json",
+  "artifactType": "application/example",
+  "blobs": [
+    {
+      "mediaType": "application/vnd.oci.image.layer.v1.tar+gzip",
+      "size": "148",
+      "digest": "sha256:c57089565e894899735d458f0fd4bb17a0f1e0df8d72da392b85c9b35ee777cd"
+    }
+  ]
+}
+`,
+			fail: true,
+		},
+
+		// expected failure: subject: size is required
+		{
+			manifest: `
+{
+  "mediaType": "application/vnd.oci.artifact.manifest.v1+json",
+  "artifactType": "application/example",
+  "subject": {
+    "mediaType": "application/vnd.oci.image.manifest.v1+json",
+    "digest": "sha256:c86f7763873b6c0aae22d963bab59b4f5debbed6685761b5951584f6efb0633b"
+  },
+  "annotations": {
+    "key1": "value1",
+    "key2": "value2"
+  }
+}
+`,
+			fail: true,
+		},
+
+		// valid manifest with optional fields
+		{
+			manifest: `
+{
+  "mediaType": "application/vnd.oci.artifact.manifest.v1+json",
+  "artifactType": "application/example",
+  "blobs": [
+    {
+      "mediaType": "application/vnd.oci.image.layer.v1.tar+gzip",
+      "size": 675598,
+      "digest": "sha256:9d3dd9504c685a304985025df4ed0283e47ac9ffa9bd0326fddf4d59513f0827"
+    },
+    {
+      "mediaType": "application/vnd.oci.image.layer.v1.tar+gzip",
+      "size": 156,
+      "digest": "sha256:2b689805fbd00b2db1df73fae47562faac1a626d5f61744bfe29946ecff5d73d"
+    },
+    {
+      "mediaType": "application/vnd.oci.image.layer.v1.tar+gzip",
+      "size": 148,
+      "digest": "sha256:c57089565e894899735d458f0fd4bb17a0f1e0df8d72da392b85c9b35ee777cd"
+    }
+  ],
+  "subject": {
+    "mediaType": "application/vnd.oci.image.manifest.v1+json",
+    "size": 1470,
+    "digest": "sha256:c86f7763873b6c0aae22d963bab59b4f5debbed6685761b5951584f6efb0633b"
+  },
+  "annotations": {
+    "key1": "value1",
+    "key2": "value2"
+  }
+}
+`,
+			fail: false,
+		},
+	} {
+		r := strings.NewReader(tt.manifest)
+		err := schema.ValidatorMediaTypeArtifact.Validate(r)
+
+		if got := err != nil; tt.fail != got {
+			t.Errorf("test %d: expected validation failure %t but got %t, err %v", i, tt.fail, got, err)
+			fmt.Println(tt.manifest)
+		}
+	}
+}

schema/schema.go

@@ -29,6 +29,7 @@ const (
 	ValidatorMediaTypeImageIndex   Validator     = v1.MediaTypeImageIndex
 	ValidatorMediaTypeImageConfig  Validator     = v1.MediaTypeImageConfig
 	ValidatorMediaTypeImageLayer   unimplemented = v1.MediaTypeImageLayer
+	ValidatorMediaTypeArtifact     Validator     = v1.MediaTypeArtifactManifest
 )
 
 var (
@@ -68,6 +69,7 @@ var (
 		ValidatorMediaTypeManifest:     "https://opencontainers.org/schema/image/image-manifest-schema.json",
 		ValidatorMediaTypeImageIndex:   "https://opencontainers.org/schema/image/image-index-schema.json",
 		ValidatorMediaTypeImageConfig:  "https://opencontainers.org/schema/image/config-schema.json",
+		ValidatorMediaTypeArtifact:     "https://opencontainers.org/schema/artifact-manifest-schema.json",
 	}
 )
 

schema/spec_test.go

@@ -54,6 +54,10 @@ func TestValidateConfig(t *testing.T) {
 	validate(t, "../config.md")
 }
 
+func TestValidateArtifactManifest(t *testing.T) {
+	validate(t, "../artifact.md")
+}
+
 func TestSchemaFS(t *testing.T) {
 	expectedSchemaFileNames, err := filepath.Glob("*.json")
 	if err != nil {

schema/validator.go

@@ -38,6 +38,7 @@ var mapValidate = map[Validator]validateFunc{
 	ValidatorMediaTypeDescriptor:  validateDescriptor,
 	ValidatorMediaTypeImageIndex:  validateIndex,
 	ValidatorMediaTypeManifest:    validateManifest,
+	ValidatorMediaTypeArtifact:    validateArtifact,
 }
 
 // ValidationError contains all the errors that happened during validation.
@@ -250,3 +251,22 @@ func checkPlatform(OS string, Architecture string) {
 	}
 	fmt.Printf("warning: operating system %q of the bundle is not supported yet.\n", OS)
 }
+
+func validateArtifact(r io.Reader) error {
+	header := v1.Artifact{}
+
+	buf, err := io.ReadAll(r)
+	if err != nil {
+		return errors.Wrapf(err, "error reading the io stream")
+	}
+
+	err = json.Unmarshal(buf, &header)
+	if err != nil {
+		return errors.Wrap(err, "manifest format mismatch")
+	}
+
+	if header.MediaType != string(v1.MediaTypeArtifactManifest) {
+		fmt.Printf("warning: Artifact has an unknown media type: %s\n", header.MediaType)
+	}
+	return nil
+}