add 'templates metadata' subcommand

src/spec-node/devContainersSpecCLI.ts

@@ -44,6 +44,7 @@ import { readFeaturesConfig } from './featureUtils';
 import { featuresGenerateDocsHandler, featuresGenerateDocsOptions } from './featuresCLI/generateDocs';
 import { templatesGenerateDocsHandler, templatesGenerateDocsOptions } from './templatesCLI/generateDocs';
 import { mapNodeOSToGOOS, mapNodeArchitectureToGOARCH } from '../spec-configuration/containerCollectionsOCI';
+import { templateMetadataHandler, templateMetadataOptions } from './templatesCLI/metadata';
 
 const defaultDefaultUserEnvProbe: UserEnvProbe = 'loginInteractiveShell';
 
@@ -85,6 +86,7 @@ const mountRegex = /^type=(bind|volume),source=([^,]+),target=([^,]+)(?:,externa
 	y.command('templates', 'Templates commands', (y: Argv) => {
 		y.command('apply', 'Apply a template to the project', templateApplyOptions, templateApplyHandler);
 		y.command('publish <target>', 'Package and publish templates', templatesPublishOptions, templatesPublishHandler);
+		y.command('metadata <templateId>', 'Fetch a published Template\'s metadata', templateMetadataOptions, templateMetadataHandler);
 		y.command('generate-docs', 'Generate documentation', templatesGenerateDocsOptions, templatesGenerateDocsHandler);
 	});
 	y.command(restArgs ? ['exec', '*'] : ['exec <cmd> [args..]'], 'Execute a command on a running dev container', execOptions, execHandler);

src/spec-node/templatesCLI/metadata.ts

@@ -0,0 +1,74 @@
+import { Argv } from 'yargs';
+import { LogLevel, mapLogLevel } from '../../spec-utils/log';
+import { getPackageConfig } from '../../spec-utils/product';
+import { createLog } from '../devContainers';
+import { fetchOCIManifestIfExists, getRef } from '../../spec-configuration/containerCollectionsOCI';
+
+import { UnpackArgv } from '../devContainersSpecCLI';
+
+export function templateMetadataOptions(y: Argv) {
+	return y
+		.options({
+			'log-level': { choices: ['info' as 'info', 'debug' as 'debug', 'trace' as 'trace'], default: 'info' as 'info', description: 'Log level.' },
+		})
+		.positional('templateId', { type: 'string', demandOption: true, description: 'Template Identifier' });
+}
+
+export type TemplateMetadataArgs = UnpackArgv<ReturnType<typeof templateMetadataOptions>>;
+
+export function templateMetadataHandler(args: TemplateMetadataArgs) {
+	(async () => await templateMetadata(args))().catch(console.error);
+}
+
+async function templateMetadata({
+	'log-level': inputLogLevel,
+	'templateId': templateId,
+}: TemplateMetadataArgs) {
+	const disposables: (() => Promise<unknown> | undefined)[] = [];
+	const dispose = async () => {
+		await Promise.all(disposables.map(d => d()));
+	};
+
+	const pkg = getPackageConfig();
+
+	const output = createLog({
+		logLevel: mapLogLevel(inputLogLevel),
+		logFormat: 'text',
+		log: (str) => process.stderr.write(str),
+		terminalDimensions: undefined,
+	}, pkg, new Date(), disposables);
+
+	const params = { output, env: process.env };
+	output.write(`Fetching metadata for ${templateId}`, LogLevel.Trace);
+
+	const templateRef = getRef(output, templateId);
+	if (!templateRef) {
+		console.log(JSON.stringify({}));
+		process.exit(1);
+	}
+
+	const manifestContainer = await fetchOCIManifestIfExists(params, templateRef, undefined);
+	if (!manifestContainer) {
+		console.log(JSON.stringify({}));
+		process.exit(1);
+	}
+
+	const { manifestObj, canonicalId } = manifestContainer;
+	output.write(`Template '${templateId}' resolved to '${canonicalId}'`, LogLevel.Trace);
+
+	// Templates must have been published with a CLI post commit
+	// https://github.com/devcontainers/cli/commit/6c6aebfa7b74aea9d67760fd1e74b09573d31536
+	// in order to contain attached metadata.
+	const metadata = manifestObj.annotations?.['dev.containers.metadata'];
+	if (!metadata) {
+		output.write(`Template resolved to '${canonicalId}' but does not contain metadata on its manifest.`, LogLevel.Warning);
+		output.write(`Ask the Template owner to republish this Template to populate the manifest.`, LogLevel.Warning);
+		console.log(JSON.stringify({}));
+		process.exit(1);
+	}
+
+	const unescaped = JSON.parse(metadata);
+	console.log(JSON.stringify(unescaped));
+	await dispose();
+	process.exit();
+}