[PoC] ui5 serve: Proxy mode

.npmrc

@@ -1,2 +1,3 @@
 # Enforce public npm registry
 registry = https://registry.npmjs.org/
+package-lock=false

lib/cli/commands/serve.js

@@ -21,13 +21,17 @@ serve.builder = function(cli) {
 			type: "string"
 		})
 		.option("h2", {
-			describe: "Shortcut for enabling the HTTP/2 protocol for the web server",
+			describe: "Enables HTTP/2 and HTTPS protocol for the web server",
 			default: false,
 			type: "boolean"
 		})
 		.option("simple-index", {
 			describe: "Use a simplified view for the server directory listing",
 			default: false,
+
+		})
+		.option("proxy", {
+			describe: "Whether or not to use a configured proxy",
 			type: "boolean"
 		})
 		.option("accept-remote-connections", {
@@ -84,7 +88,7 @@ serve.handler = async function(argv) {
 	let changePortIfInUse = false;
 
 	if (!port && tree.server && tree.server.settings) {
-		if (argv.h2) {
+		if (argv.h2 || argv.proxy) {
 			port = tree.server.settings.httpsPort;
 		} else {
 			port = tree.server.settings.httpPort;
@@ -93,33 +97,43 @@ serve.handler = async function(argv) {
 
 	if (!port) {
 		changePortIfInUse = true; // only change if port isn't explicitly set
-		if (argv.h2) {
+		if (argv.h2 || argv.proxy) {
 			port = 8443;
 		} else {
 			port = 8080;
 		}
 	}
+	let cdnUrl;
+	if (tree.server && tree.server.cdnUrl) {
+		if (tree.specVersion !== "2.2a") {
+			throw new Error(`Server configuration "cdnUrl" can only be used with specification version "2.2a". ` +
+				`But project ${tree.metadata.name} defines "${tree.specVersion}".`);
+		}
+		cdnUrl = tree.server.cdnUrl;
+	}
 
 	const serverConfig = {
 		port,
 		changePortIfInUse,
 		h2: argv.h2,
+		useProxy: argv.proxy,
 		simpleIndex: !!argv.simpleIndex,
 		acceptRemoteConnections: !!argv.acceptRemoteConnections,
 		cert: argv.h2 ? argv.cert : undefined,
 		key: argv.h2 ? argv.key : undefined,
-		sendSAPTargetCSP: !!argv.sapCspPolicies
+		sendSAPTargetCSP: !!argv.sapCspPolicies,
+		cdnUrl
 	};
 
-	if (serverConfig.h2) {
+	if (serverConfig.h2 || argv.proxy) {
 		const {key, cert} = await ui5Server.sslUtil.getSslCertificate(serverConfig.key, serverConfig.cert);
 		serverConfig.key = key;
 		serverConfig.cert = cert;
 	}
 
 	const {h2, port: actualPort} = await server.serve(tree, serverConfig);
 
-	const protocol = h2 ? "https" : "http";
+	const protocol = (h2 || argv.proxy) ? "https" : "http";
 	let browserUrl = protocol + "://localhost:" + actualPort;
 	console.log("Server started");
 	console.log("URL: " + browserUrl);