Detect registry hosts in image names like Docker does

src/spec-configuration/containerCollectionsOCI.ts

@@ -223,7 +223,7 @@ export function getRef(output: Log, input: string): OCIRef | undefined {
 	const registry = splitOnSlash[0];
 	const namespace = splitOnSlash.slice(1, -1).join('/');
 
-	const path = `${namespace}/${id}`;
+	const path = splitOnSlash.length < 2 ? `/${id}` : (namespace ? `${namespace}/${id}` : id);
 
 	if (!regexForPath.exec(path)) {
 		output.write(`Path '${path}' for input '${input}' failed validation.  Expected path to match regex '${regexForPath}'.`, LogLevel.Error);

src/spec-node/containerFeatures.ts

@@ -11,7 +11,7 @@ import { LogLevel, makeLog } from '../spec-utils/log';
 import { FeaturesConfig, getContainerFeaturesBaseDockerFile, getFeatureInstallWrapperScript, getFeatureLayers, getFeatureMainValue, getFeatureValueObject, generateFeaturesConfig, Feature, generateContainerEnvs } from '../spec-configuration/containerFeaturesConfiguration';
 import { readLocalFile } from '../spec-utils/pfs';
 import { includeAllConfiguredFeatures } from '../spec-utils/product';
-import { createFeaturesTempFolder, DockerResolverParameters, getCacheFolder, getFolderImageName, getEmptyContextFolder, SubstitutedConfig, isBuildxCacheToInline } from './utils';
+import { createFeaturesTempFolder, DockerResolverParameters, getCacheFolder, getFolderImageName, getEmptyContextFolder, hasRegistryHost, SubstitutedConfig, isBuildxCacheToInline } from './utils';
 import { isEarlierVersion, parseVersion, runCommandNoPty } from '../spec-common/commonUtils';
 import { getDevcontainerMetadata, getDevcontainerMetadataLabel, getImageBuildInfoFromImage, ImageBuildInfo, ImageMetadataEntry, imageMetadataLabel, MergedDevContainerConfig } from './imageMetadata';
 import { supportsBuildContexts } from './dockerfileUtils';
@@ -467,7 +467,7 @@ export async function updateRemoteUserUID(params: DockerResolverParameters, merg
 		'-f', destDockerfile,
 		'-t', fixedImageName,
 		...(platform ? ['--platform', platform] : []),
-		'--build-arg', `BASE_IMAGE=${params.cliVariant === CLIVariant.Podman && !hasRegistryHostname(imageName) ? 'localhost/' : ''}${imageName}`, // Podman: https://github.com/microsoft/vscode-remote-release/issues/9748
+		'--build-arg', `BASE_IMAGE=${params.cliVariant === CLIVariant.Podman && !hasRegistryHost(imageName) ? 'localhost/' : ''}${imageName}`, // Podman: https://github.com/microsoft/vscode-remote-release/issues/9748
 		'--build-arg', `REMOTE_USER=${remoteUser}`,
 		'--build-arg', `NEW_UID=${await cliHost.getuid!()}`,
 		'--build-arg', `NEW_GID=${await cliHost.getgid!()}`,
@@ -481,12 +481,3 @@ export async function updateRemoteUserUID(params: DockerResolverParameters, merg
 	}
 	return fixedImageName;
 }
-
-function hasRegistryHostname(imageName: string) {
-	if (imageName.startsWith('localhost/')) {
-		return true;
-	}
-	const dot = imageName.indexOf('.');
-	const slash = imageName.indexOf('/');
-	return dot !== -1 && slash !== -1 && dot < slash;
-}

src/spec-node/utils.ts

@@ -379,19 +379,28 @@ export async function inspectImageInRegistry(output: Log, platformInfo: Platform
 	};
 }
 
+// Same rule as Docker's splitDockerDomain: https://github.com/distribution/reference
+export function hasRegistryHost(name: string): boolean {
+	const slash = name.indexOf('/');
+	if (slash <= 0) {
+		return false;
+	}
+	const registry = name.substring(0, slash);
+	return registry.includes('.') || registry.includes(':') || registry === 'localhost' || registry !== registry.toLowerCase();
+}
+
 export function qualifyImageName(name: string) {
 	const segments = name.split('/');
 	if (segments.length === 1) {
 		return `docker.io/library/${name}`;
-	} else if (segments.length === 2) {
-		if (name.startsWith('docker.io/')) {
-			return `docker.io/library/${segments[1]}`;
-		} else {
-			return `docker.io/${name}`;
-		}
-	} else {
+	}
+	if (segments[0] === 'docker.io') {
+		return segments.length === 2 ? `docker.io/library/${segments[1]}` : name;
+	}
+	if (hasRegistryHost(name)) {
 		return name;
 	}
+	return `docker.io/${name}`;
 }
 
 export interface DevContainerAuthority {

src/test/dockerUtils.test.ts

@@ -4,7 +4,8 @@
  *--------------------------------------------------------------------------------------------*/
 
 import { createPlainLog, LogLevel, makeLog } from '../spec-utils/log';
-import { inspectImageInRegistry, qualifyImageName } from '../spec-node/utils';
+import { getRef } from '../spec-configuration/containerCollectionsOCI';
+import { hasRegistryHost, inspectImageInRegistry, qualifyImageName } from '../spec-node/utils';
 import assert from 'assert';
 import { dockerCLI, listContainers, PartialExecParameters, removeContainer, toExecParameters } from '../spec-shutdown/dockerUtils';
 import { createCLIParams } from './testUtils';
@@ -42,11 +43,36 @@ describe('Docker utils', function () {
 		assert.ok(config.Config.Cmd);
 	});
 
+	it('detects a registry host', () => {
+		assert.strictEqual(hasRegistryHost('myregistry:5000/image'), true);
+		assert.strictEqual(hasRegistryHost('random/image'), false);
+	});
+
 	it('qualifies docker.io shorthands', async () => {
 		assert.strictEqual(qualifyImageName('ubuntu'), 'docker.io/library/ubuntu');
 		assert.strictEqual(qualifyImageName('docker.io/ubuntu'), 'docker.io/library/ubuntu');
 		assert.strictEqual(qualifyImageName('random/image'), 'docker.io/random/image');
-		assert.strictEqual(qualifyImageName('foo/random/image'), 'foo/random/image');
+		assert.strictEqual(qualifyImageName('foo/random/image'), 'docker.io/foo/random/image');
+	});
+
+	it('keeps an uppercase registry host', () => {
+		assert.strictEqual(qualifyImageName('Registry/image'), 'Registry/image');
+	});
+
+	it('keeps a localhost registry host', () => {
+		assert.strictEqual(qualifyImageName('localhost/image'), 'localhost/image');
+		assert.strictEqual(qualifyImageName('localhost:5000/ns/image'), 'localhost:5000/ns/image');
+	});
+
+	it('keeps a registry host with a dot', () => {
+		assert.strictEqual(qualifyImageName('registry.example.com/image'), 'registry.example.com/image');
+	});
+
+	it('resolves a registry host with a port', () => {
+		const ref = getRef(output, qualifyImageName('registry.example.com:5000/image:tag'));
+		assert.strictEqual(ref?.registry, 'registry.example.com:5000');
+		assert.strictEqual(ref?.path, 'image');
+		assert.strictEqual(ref?.version, 'tag');
 	});
 
 	it('protects against concurrent removal', async () => {