Changes the config layer of the feature manifest to a empty descriptor (#815)

* Change the config layer of the feature manifest to a empty descriptor

This commit changes the config layer of the feature manifest to a empty descriptor according to the OCI image manifest specification to to increase the available feature registry.

Some registries that implement the OCI image manifest specification, such as AWS ECR, do not support pushing empty content (size 0). However, the manifest may contain layers with no content. Therefore, the OCI Image Manifest specification specifies an empty descriptor of non-zero size to represent a layer with no content.

Currently, the devcontainer feature manifest specifies the config layer as an empty content (size 0) layer. If the devcontainer feature manifest conforms to this specification, it can also available registries that cannot publish empty content (size 0).

Specification: https://github.com/opencontainers/image-spec/blob/8f3820ccf8f65db8744e626df17fe8a64462aece/manifest.md#guidelines-for-artifact-usage

Note: If the config is set to an empty descriptor, the manifest media type must be defined in the artifactType.

* Revert "Change the config layer of the feature manifest to a empty descriptor"

This reverts commit 1b290f0.

* Changing the content of the config layer to an empty object

The content of the configuration layer of the feature manifest is specified as empty content (size 0).
This is because there is no content to reference in the config layer content of the feature manifest.

However, some registries that implement the OCI image manifest specification, such as AWS ECR, do not
support pushing empty content (size 0).
Therefore, this commit changes the content of the config layer of the feature manifestto indicate that
empty objects have no content to reference.

* Revert the test of push against the GitHub registry and fix/add the comments

* Change the feature that test depends on

Author: ych-tnk

.gitignore

@@ -15,3 +15,4 @@ output
 src/test/container-features/configs/temp_lifecycle-hooks-alternative-order
 test-secrets-temp.json
 src/test/container-*/**/src/**/README.md
+!src/test/container-features/assets/*.tgz

src/spec-configuration/containerCollectionsOCIPush.ts

@@ -44,8 +44,8 @@ export async function pushOCIFeatureOrTemplate(params: CommonParams, ociRef: OCI
 		{
 			name: 'configLayer',
 			digest: manifest.manifestObj.config.digest,
-			contents: Buffer.alloc(0),
 			size: manifest.manifestObj.config.size,
+			contents: Buffer.from('{}'),
 		},
 		{
 			name: 'tgzLayer',
@@ -119,7 +119,7 @@ export async function pushCollectionMetadata(params: CommonParams, collectionRef
 			name: 'configLayer',
 			digest: manifest.manifestObj.config.digest,
 			size: manifest.manifestObj.config.size,
-			contents: Buffer.alloc(0),
+			contents: Buffer.from('{}'),
 		},
 		{
 			name: 'collectionLayer',
@@ -382,16 +382,16 @@ async function postUploadSessionId(params: CommonParams, ociRef: OCIRef | OCICol
 export async function calculateManifestAndContentDigest(output: Log, ociRef: OCIRef | OCICollectionRef, dataLayer: OCILayer, annotations: { [key: string]: string } | undefined): Promise<ManifestContainer> {
 	// A canonical manifest digest is the sha256 hash of the JSON representation of the manifest, without the signature content.
 	// See: https://docs.docker.com/registry/spec/api/#content-digests
-	// Below is an example of a serialized manifest that should resolve to '9726054859c13377c4c3c3c73d15065de59d0c25d61d5652576c0125f2ea8ed3'
-	// {"schemaVersion":2,"mediaType":"application/vnd.oci.image.manifest.v1+json","config":{"mediaType":"application/vnd.devcontainers","digest":"sha256:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855","size":0},"layers":[{"mediaType":"application/vnd.devcontainers.layer.v1+tar","digest":"sha256:b2006e7647191f7b47222ae48df049c6e21a4c5a04acfad0c4ef614d819de4c5","size":15872,"annotations":{"org.opencontainers.image.title":"go.tgz"}}]}
+	// Below is an example of a serialized manifest that should resolve to 'dd328c25cc7382aaf4e9ee10104425d9a2561b47fe238407f6c0f77b3f8409fc'
+	// {"schemaVersion":2,"mediaType":"application/vnd.oci.image.manifest.v1+json","config":{"mediaType":"application/vnd.devcontainers","digest":"sha256:44136fa355b3678a1146ad16f7e8649e94fb4fc21fe77e8310c060f61caaff8a","size":2},"layers":[{"mediaType":"application/vnd.devcontainers.layer.v1+tar","digest":"sha256:0bb92d2da46d760c599d0a41ed88d52521209408b529761417090b62ee16dfd1","size":3584,"annotations":{"org.opencontainers.image.title":"devcontainer-feature-color.tgz"}}],"annotations":{"dev.containers.metadata":"{\"id\":\"color\",\"version\":\"1.0.0\",\"name\":\"A feature to remind you of your favorite color\",\"options\":{\"favorite\":{\"type\":\"string\",\"enum\":[\"red\",\"gold\",\"green\"],\"default\":\"red\",\"description\":\"Choose your favorite color.\"}}}","com.github.package.type":"devcontainer_feature"}}
 
 	let manifest: OCIManifest = {
 		schemaVersion: 2,
 		mediaType: 'application/vnd.oci.image.manifest.v1+json',
 		config: {
 			mediaType: 'application/vnd.devcontainers',
-			digest: 'sha256:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855', // A zero byte digest for the devcontainer mediaType.
-			size: 0
+			digest: 'sha256:44136fa355b3678a1146ad16f7e8649e94fb4fc21fe77e8310c060f61caaff8a', // A empty json byte digest for the devcontainer mediaType.
+			size: 2
 		},
 		layers: [
 			dataLayer

src/test/container-features/assets/devcontainer-feature-color.tgz

@@ -305,26 +305,26 @@ registry`;
 });
 
 //  NOTE: 
-//  Test depends on https://github.com/codspace/features/pkgs/container/features%2Fgo/29819216?tag=1
+//  Test depends on https://github.com/orgs/codspace/packages/container/non-empty-config-layer%2Fcolor/225254837?tag=1.0.0
 describe('Test OCI Push Helper Functions', function () {
 	this.timeout('10s');
 	it('Generates the correct tgz manifest layer', async () => {
 
-		const dataBytes = fs.readFileSync(`${testAssetsDir}/go.tgz`);
+		const dataBytes = fs.readFileSync(`${testAssetsDir}/devcontainer-feature-color.tgz`);
 
-		const featureRef = getRef(output, 'ghcr.io/devcontainers/features/go');
+		const featureRef = getRef(output, 'ghcr.io/codspace/non-empty-config-layer/color');
 		if (!featureRef) {
 			assert.fail();
 		}
 
 		// Calculate the tgz layer and digest
-		const res = await calculateDataLayer(output, dataBytes, 'go.tgz', DEVCONTAINER_TAR_LAYER_MEDIATYPE);
+		const res = await calculateDataLayer(output, dataBytes, 'devcontainer-feature-color.tgz', DEVCONTAINER_TAR_LAYER_MEDIATYPE);
 		const expected = {
-			digest: 'sha256:b2006e7647191f7b47222ae48df049c6e21a4c5a04acfad0c4ef614d819de4c5',
+			digest: 'sha256:0bb92d2da46d760c599d0a41ed88d52521209408b529761417090b62ee16dfd1',
 			mediaType: 'application/vnd.devcontainers.layer.v1+tar',
-			size: 15872,
+			size: 3584,
 			annotations: {
-				'org.opencontainers.image.title': 'go.tgz'
+				'org.opencontainers.image.title': 'devcontainer-feature-color.tgz'
 			}
 		};
 
@@ -334,35 +334,39 @@ describe('Test OCI Push Helper Functions', function () {
 		assert.deepEqual(res, expected);
 
 		// Generate entire manifest to be able to calculate content digest
-		const manifestContainer = await calculateManifestAndContentDigest(output, featureRef, res, undefined);
+		const annotations = {
+			'dev.containers.metadata': '{\"id\":\"color\",\"version\":\"1.0.0\",\"name\":\"A feature to remind you of your favorite color\",\"options\":{\"favorite\":{\"type\":\"string\",\"enum\":[\"red\",\"gold\",\"green\"],\"default\":\"red\",\"description\":\"Choose your favorite color.\"}}}',
+			'com.github.package.type': 'devcontainer_feature'
+		};
+		const manifestContainer = await calculateManifestAndContentDigest(output, featureRef, res, annotations);
 		if (!manifestContainer) {
 			assert.fail();
 		}
 		const { contentDigest, manifestBuffer } = manifestContainer;
 
 		// 'Expected' is taken from intermediate value in oras reference implementation, before hash calculation
-		assert.strictEqual('{"schemaVersion":2,"mediaType":"application/vnd.oci.image.manifest.v1+json","config":{"mediaType":"application/vnd.devcontainers","digest":"sha256:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855","size":0},"layers":[{"mediaType":"application/vnd.devcontainers.layer.v1+tar","digest":"sha256:b2006e7647191f7b47222ae48df049c6e21a4c5a04acfad0c4ef614d819de4c5","size":15872,"annotations":{"org.opencontainers.image.title":"go.tgz"}}]}', manifestBuffer.toString());
+		assert.strictEqual('{"schemaVersion":2,"mediaType":"application/vnd.oci.image.manifest.v1+json","config":{"mediaType":"application/vnd.devcontainers","digest":"sha256:44136fa355b3678a1146ad16f7e8649e94fb4fc21fe77e8310c060f61caaff8a","size":2},"layers":[{"mediaType":"application/vnd.devcontainers.layer.v1+tar","digest":"sha256:0bb92d2da46d760c599d0a41ed88d52521209408b529761417090b62ee16dfd1","size":3584,"annotations":{"org.opencontainers.image.title":"devcontainer-feature-color.tgz"}}],"annotations":{"dev.containers.metadata":"{\\"id\\":\\"color\\",\\"version\\":\\"1.0.0\\",\\"name\\":\\"A feature to remind you of your favorite color\\",\\"options\\":{\\"favorite\\":{\\"type\\":\\"string\\",\\"enum\\":[\\"red\\",\\"gold\\",\\"green\\"],\\"default\\":\\"red\\",\\"description\\":\\"Choose your favorite color.\\"}}}","com.github.package.type":"devcontainer_feature"}}', manifestBuffer.toString());
 
 		// This is the canonical digest of the manifest
-		assert.strictEqual('sha256:9726054859c13377c4c3c3c73d15065de59d0c25d61d5652576c0125f2ea8ed3', contentDigest);
+		assert.strictEqual('sha256:dd328c25cc7382aaf4e9ee10104425d9a2561b47fe238407f6c0f77b3f8409fc', contentDigest);
 	});
 
 	it('Can fetch an artifact from a digest reference', async () => {
-		const manifest = await fetchOCIFeatureManifestIfExistsFromUserIdentifier({ output, env: process.env }, 'ghcr.io/codspace/features/go', 'sha256:9726054859c13377c4c3c3c73d15065de59d0c25d61d5652576c0125f2ea8ed3');
-		assert.strictEqual(manifest?.manifestObj.layers[0].annotations['org.opencontainers.image.title'], 'go.tgz');
+		const manifest = await fetchOCIFeatureManifestIfExistsFromUserIdentifier({ output, env: process.env }, 'ghcr.io/codspace/non-empty-config-layer/color', 'sha256:dd328c25cc7382aaf4e9ee10104425d9a2561b47fe238407f6c0f77b3f8409fc');
+		assert.strictEqual(manifest?.manifestObj.layers[0].annotations['org.opencontainers.image.title'], 'devcontainer-feature-color.tgz');
 	});
 
 	it('Can check whether a blob exists', async () => {
-		const ociFeatureRef = getRef(output, 'ghcr.io/codspace/features/go:1');
+		const ociFeatureRef = getRef(output, 'ghcr.io/codspace/non-empty-config-layer/color:1.0.0');
 		if (!ociFeatureRef) {
 			assert.fail('getRef() for the Feature should not be undefined');
 		}
 
 
-		const tarLayerBlobExists = await checkIfBlobExists({ output, env: process.env }, ociFeatureRef, 'sha256:b2006e7647191f7b47222ae48df049c6e21a4c5a04acfad0c4ef614d819de4c5');
+		const tarLayerBlobExists = await checkIfBlobExists({ output, env: process.env }, ociFeatureRef, 'sha256:0bb92d2da46d760c599d0a41ed88d52521209408b529761417090b62ee16dfd1');
 		assert.isTrue(tarLayerBlobExists);
 
-		const configLayerBlobExists = await checkIfBlobExists({ output, env: process.env }, ociFeatureRef, 'sha256:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855');
+		const configLayerBlobExists = await checkIfBlobExists({ output, env: process.env }, ociFeatureRef, 'sha256:44136fa355b3678a1146ad16f7e8649e94fb4fc21fe77e8310c060f61caaff8a');
 		assert.isTrue(configLayerBlobExists);
 
 		const randomStringDoesNotExist = await checkIfBlobExists({ output, env: process.env }, ociFeatureRef, 'sha256:41af286dc0b172ed2f1ca934fd2278de4a1192302ffa07087cea2682e7d372e3');