Feature/mssql-big-data-cluster (#4107)

* Adding kubernetes installer.

* Adding variety of kubectl support and integrating into the kubeconfig target cluster page.

* Addressing PR comments, refactored utility file locations and added missing license headers.

extensions/big-data-cluster/src/installer/download.ts

@@ -0,0 +1,45 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the Source EULA. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import * as path from 'path';
+import * as stream from 'stream';
+import * as tmp from 'tmp';
+
+import { succeeded, Errorable } from '../interfaces';
+
+type DownloadFunc =
+    (url: string, destination?: string, options?: any)
+         => Promise<Buffer> & stream.Duplex; // Stream has additional events - see https://www.npmjs.com/package/download
+
+let download: DownloadFunc;
+
+function ensureDownloadFunc() {
+    if (!download) {
+        const home = process.env['HOME'];
+        download = require('download');
+        if (home) {
+            process.env['HOME'] = home;
+        }
+    }
+}
+
+export async function toTempFile(sourceUrl: string): Promise<Errorable<string>> {
+    const tempFileObj = tmp.fileSync({ prefix: "mssql-bdc-autoinstall-" });
+    const downloadResult = await to(sourceUrl, tempFileObj.name);
+    if (succeeded(downloadResult)) {
+        return { succeeded: true, result: tempFileObj.name };
+    }
+    return { succeeded: false, error: downloadResult.error };
+}
+
+export async function to(sourceUrl: string, destinationFile: string): Promise<Errorable<null>> {
+    ensureDownloadFunc();
+    try {
+        await download(sourceUrl, path.dirname(destinationFile), { filename: path.basename(destinationFile) });
+        return { succeeded: true, result: null };
+    } catch (e) {
+        return { succeeded: false, error: [e.message] };
+    }
+}

extensions/big-data-cluster/src/installer/installer.ts

@@ -0,0 +1,69 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the Source EULA. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+'use strict';
+
+import * as download from './download';
+import * as fs from 'fs';
+import mkdirp = require('mkdirp');
+import * as path from 'path';
+import { Shell, Platform } from '../utility/shell';
+import { Errorable, failed } from '../interfaces';
+import { addPathToConfig, toolPathBaseKey } from '../config/config';
+
+export async function installKubectl(shell: Shell): Promise<Errorable<null>> {
+    const tool = 'kubectl';
+    const binFile = (shell.isUnix()) ? 'kubectl' : 'kubectl.exe';
+    const os = platformUrlString(shell.platform());
+
+    const version = await getStableKubectlVersion();
+    if (failed(version)) {
+        return { succeeded: false, error: version.error };
+    }
+
+    const installFolder = getInstallFolder(shell, tool);
+    mkdirp.sync(installFolder);
+
+    const kubectlUrl = `https://storage.googleapis.com/kubernetes-release/release/${version.result.trim()}/bin/${os}/amd64/${binFile}`;
+    const downloadFile = path.join(installFolder, binFile);
+    const downloadResult = await download.to(kubectlUrl, downloadFile);
+    if (failed(downloadResult)) {
+        return { succeeded: false, error: [`Failed to download kubectl: ${downloadResult.error[0]}`] };
+    }
+
+    if (shell.isUnix()) {
+        fs.chmodSync(downloadFile, '0777');
+    }
+
+    await addPathToConfig(toolPathBaseKey(tool), downloadFile);
+    return { succeeded: true, result: null };
+}
+
+async function getStableKubectlVersion(): Promise<Errorable<string>> {
+    const downloadResult = await download.toTempFile('https://storage.googleapis.com/kubernetes-release/release/stable.txt');
+    if (failed(downloadResult)) {
+        return { succeeded: false, error: [`Failed to establish kubectl stable version: ${downloadResult.error[0]}`] };
+    }
+    const version = fs.readFileSync(downloadResult.result, 'utf-8');
+    fs.unlinkSync(downloadResult.result);
+    return { succeeded: true, result: version };
+}
+
+export function getInstallFolder(shell: Shell, tool: string): string {
+    return path.join(shell.home(), `.mssql-bdc/tools/${tool}`);
+}
+
+function platformUrlString(platform: Platform, supported?: Platform[]): string | null {
+    if (supported && supported.indexOf(platform) < 0) {
+        return null;
+    }
+    switch (platform) {
+        case Platform.Windows: return 'windows';
+        case Platform.MacOS: return 'darwin';
+        case Platform.Linux: return 'linux';
+        default: return null;
+    }
+}
+
+