Add support for "extends" keyword

package.json

@@ -91,6 +91,7 @@
 	},
 	"dependencies": {
 		"chalk": "^4",
+		"deepmerge-ts": "^4.2.2",
 		"follow-redirects": "^1.14.8",
 		"js-yaml": "^4.1.0",
 		"jsonc-parser": "^3.0.0",

src/spec-configuration/configuration.ts

@@ -73,6 +73,7 @@ export interface DevContainerFromImageConfig {
 	features?: Record<string, string | boolean | Record<string, string | boolean>>;
 	overrideFeatureInstallOrder?: string[];
 	hostRequirements?: HostRequirements;
+	extends?: string;
 	customizations?: Record<string, any>;
 }
 
@@ -110,6 +111,7 @@ export type DevContainerFromDockerfileConfig = {
 	features?: Record<string, string | boolean | Record<string, string | boolean>>;
 	overrideFeatureInstallOrder?: string[];
 	hostRequirements?: HostRequirements;
+	extends?: string;
 	customizations?: Record<string, any>;
 } & (
 		{
@@ -166,6 +168,7 @@ export interface DevContainerFromDockerComposeConfig {
 	features?: Record<string, string | boolean | Record<string, string | boolean>>;
 	overrideFeatureInstallOrder?: string[];
 	hostRequirements?: HostRequirements;
+	extends?: string;
 	customizations?: Record<string, any>;
 }
 

src/spec-node/configContainer.ts

@@ -3,9 +3,9 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
-import * as path from 'path';
-
+import * as deepmerge from 'deepmerge-ts';
 import * as jsonc from 'jsonc-parser';
+import * as path from 'path';
 
 import { openDockerfileDevContainer } from './singleContainer';
 import { openDockerComposeDevContainer } from './dockerCompose';
@@ -71,26 +71,41 @@ async function resolveWithLocalFolder(params: DockerResolverParameters, parsedAu
 	return result;
 }
 
-export async function readDevContainerConfigFile(cliHost: CLIHost, workspace: Workspace | undefined, configFile: URI, mountWorkspaceGitRoot: boolean, output: Log, consistency?: BindMountConsistency, overrideConfigFile?: URI) {
+async function readFile(cliHost: CLIHost, path: URI) {
 	const documents = createDocuments(cliHost);
-	const content = await documents.readDocument(overrideConfigFile ?? configFile);
+	const content = await documents.readDocument(path);
 	if (!content) {
 		return undefined;
 	}
 	const raw = jsonc.parse(content) as DevContainerConfig | undefined;
 	const updated = raw && updateFromOldProperties(raw);
 	if (!updated || typeof updated !== 'object' || Array.isArray(updated)) {
-		throw new ContainerError({ description: `Dev container config (${uriToFsPath(configFile, cliHost.platform)}) must contain a JSON object literal.` });
+		throw new ContainerError({ description: `Dev container config (${uriToFsPath(path, cliHost.platform)}) must contain a JSON object literal.` });
 	}
-	const workspaceConfig = await getWorkspaceConfiguration(cliHost, workspace, updated, mountWorkspaceGitRoot, output, consistency);
+
+	return updated;
+}
+
+export async function readDevContainerConfigFile(cliHost: CLIHost, workspace: Workspace | undefined, configFile: URI, mountWorkspaceGitRoot: boolean, output: Log, consistency?: BindMountConsistency, overrideConfigFile?: URI) {
+	const confPath = overrideConfigFile ?? configFile;
+	let content = await readFile(cliHost, confPath) as DevContainerConfig;
+
+	if (content.extends) {
+		const extendsConfPath = path.resolve(path.dirname(confPath.path), content.extends);
+		const referencedContent = await readFile(cliHost, URI.file(extendsConfPath)) as DevContainerConfig;
+		delete content.extends;
+		content = deepmerge.deepmerge(referencedContent, content);
+	}
+
+	const workspaceConfig = await getWorkspaceConfiguration(cliHost, workspace, content, mountWorkspaceGitRoot, output, consistency);
 	const substitute0: SubstituteConfig = value => substitute({
 		platform: cliHost.platform,
 		localWorkspaceFolder: workspace?.rootFolderPath,
 		containerWorkspaceFolder: workspaceConfig.workspaceFolder,
 		configFile,
 		env: cliHost.env,
 	}, value);
-	const config: DevContainerConfig = substitute0(updated);
+	const config: DevContainerConfig = substitute0(content);
 	if (typeof config.workspaceFolder === 'string') {
 		workspaceConfig.workspaceFolder = config.workspaceFolder;
 	}
@@ -101,7 +116,7 @@ export async function readDevContainerConfigFile(cliHost: CLIHost, workspace: Wo
 	return {
 		config: {
 			config,
-			raw: updated,
+			raw: content,
 			substitute: substitute0,
 		},
 		workspaceConfig,

src/test/configs/extends/.devcontainer.base.json

@@ -0,0 +1,10 @@
+{
+    "name": "example configuration",
+    "image": "mcr.microsoft.com/devcontainers/base:latest",
+    "forwardPorts": [80],
+    "features": {
+        "ghcr.io/devcontainers/features/go:1": {
+            "version": "latest"
+        }
+    }
+}

src/test/configs/extends/.devcontainer.json

@@ -0,0 +1,11 @@
+{
+	"extends": "./.devcontainer.base.json",
+	"name": "Overrides",
+	"forwardPorts": [443],
+	"features": {
+		"ghcr.io/devcontainers/features/docker-in-docker:1": {
+			"version": "latest",
+			"moby": true
+		}
+	}
+}

src/test/spec-node/configContainers.test.ts

@@ -0,0 +1,63 @@
+import path from 'path';
+import { getCLIHost } from '../../spec-common/cliHost';
+import { loadNativeModule } from '../../spec-common/commonUtils';
+import { readDevContainerConfigFile } from '../../spec-node/configContainer';
+import { nullLog } from '../../spec-utils/log';
+import { URI } from 'vscode-uri';
+import { assert } from 'chai';
+
+describe('readDevContainerConfigFile', async function () {
+	it('can read a basic configuration file', async function () {
+		const cwd = process.cwd();
+		const cliHost = await getCLIHost(cwd, loadNativeModule);
+		const workspace = {
+			isWorkspaceFile: true,
+			workspaceOrFolderPath: '/foo/bar',
+			rootFolderPath: '/foo/bar',
+			configFolderPath: '/foo/bar',
+		};
+		const configFile = URI.file(path.resolve('./src/test/configs/example/.devcontainer.json'));
+
+		const configs = await readDevContainerConfigFile(cliHost, workspace, configFile, false, nullLog);
+		assert.isNotNull(configs);
+		assert.property(configs, 'config');
+		assert.isNotNull(configs?.config.config);
+
+		const features = configs?.config.config.features as Record<string, string | boolean | Record<string, string | boolean>>;
+		assert.hasAllKeys(features, ['ghcr.io/devcontainers/features/go:1']);
+	});
+
+	it('can resolve an "extends" file reference', async function () {
+		const cwd = process.cwd();
+		const cliHost = await getCLIHost(cwd, loadNativeModule);
+		const workspace = {
+			isWorkspaceFile: true,
+			workspaceOrFolderPath: '/foo/bar',
+			rootFolderPath: '/foo/bar',
+			configFolderPath: '/foo/bar',
+		};
+		const configFile = URI.file(path.resolve('./src/test/configs/extends/.devcontainer.json'));
+
+		const configs = await readDevContainerConfigFile(cliHost, workspace, configFile, false, nullLog);
+		assert.isNotNull(configs);
+		assert.property(configs, 'config');
+		assert.isNotNull(configs?.config.config);
+		assert.isNotNull(configs?.config.raw);
+		const expectedConfig = {
+			name: 'Overrides',
+			image: 'mcr.microsoft.com/devcontainers/base:latest',
+			forwardPorts: [ 80, 443 ],
+			features: {
+				'ghcr.io/devcontainers/features/docker-in-docker:1': {
+					'version': 'latest',
+					'moby': true
+				},
+				'ghcr.io/devcontainers/features/go:1': {
+					'version': 'latest'
+				}
+			}
+		};
+
+		assert.deepEqual(configs?.config.raw as any, expectedConfig);
+	});
+});

yarn.lock

@@ -815,6 +815,11 @@ deep-is@^0.1.3, deep-is@~0.1.3:
   resolved "https://registry.yarnpkg.com/deep-is/-/deep-is-0.1.3.tgz#b369d6fb5dbc13eecf524f91b070feedc357cf34"
   integrity sha1-s2nW+128E+7PUk+RsHD+7cNXzzQ=
 
+deepmerge-ts@^4.2.2:
+  version "4.2.2"
+  resolved "https://registry.yarnpkg.com/deepmerge-ts/-/deepmerge-ts-4.2.2.tgz#582bf34a37592dc8274b137617b539f871aaf11a"
+  integrity sha512-Ka3Kb21tiWjvQvS9U+1Dx+aqFAHsdTnMdYptLTmC2VAmDFMugWMY1e15aTODstipmCun8iNuqeSfcx6rsUUk0Q==
+
 define-properties@^1.1.3:
   version "1.1.3"
   resolved "https://registry.yarnpkg.com/define-properties/-/define-properties-1.1.3.tgz#cf88da6cbee26fe6db7094f61d870cbd84cee9f1"