packages/cli: lazy-load commands to speed up cli boot time

packages/cli/bin/backstage-cli

@@ -12,25 +12,33 @@ if (!isLocal) {
   // This is a solution for getting src-relative imports to work with typescript/node in
   // the published package. We're using `module: "amd"` to ship the entire cli implementation
   // in one file, and it also happens to generate correct module definition and import statements.
-
   // Minimal AMD implementation
   const moduleFactories = {};
   const moduleCache = {};
   global.define = (name, deps, moduleFunc) => {
     moduleFactories[name] = () => {
       const exportsObj = {};
-      const impls = deps.slice(2).map(dep => {
-        const factory = moduleFactories[dep];
-        if (!factory) {
-          return require(dep);
-        }
-        if (!moduleCache[dep]) {
-          moduleCache[dep] = factory();
-        }
-        return moduleCache[dep];
-      });
 
-      moduleFunc(require, exportsObj, ...impls);
+      // require() that first searches for locally defined amd modules
+      const requireFunc = name => {
+        let factory = moduleFactories[name];
+        if (!factory) {
+          // Check /index as well, to mirror nodejs resolution
+          const index = `${name}/index`;
+          if (!moduleFactories[index]) {
+            return require(name);
+          }
+          name = index;
+          factory = moduleFactories[name];
+        }
+        if (!moduleCache[name]) {
+          moduleCache[name] = factory();
+        }
+        return moduleCache[name];
+      };
+      const impls = deps.slice(2).map(requireFunc);
+
+      moduleFunc(requireFunc, exportsObj, ...impls);
 
       return exportsObj;
     };

packages/cli/src/index.ts

@@ -16,16 +16,6 @@
 
 import program from 'commander';
 import chalk from 'chalk';
-import createAppCommand from './commands/create-app/createApp';
-import createPluginCommand from './commands/create-plugin/createPlugin';
-import watch from './commands/watch-deps';
-import buildCache from './commands/build-cache';
-import lintCommand from './commands/lint';
-import testCommand from './commands/testCommand';
-import appBuild from './commands/app/build';
-import appServe from './commands/app/serve';
-import pluginBuild from './commands/plugin/build';
-import pluginServe from './commands/plugin/serve';
 import { exitWithError } from './helpers/errors';
 import { paths } from './helpers/paths';
 
@@ -37,51 +27,53 @@ const main = (argv: string[]) => {
   program
     .command('create-app')
     .description('Creates a new app in a new directory')
-    .action(actionHandler(createAppCommand));
+    .action(actionHandler(() => require('commands/create-app/createApp')));
 
   program
     .command('app:build')
     .description('Build an app for a production release')
-    .action(actionHandler(appBuild));
+    .action(actionHandler(() => require('commands/app/build')));
 
   program
     .command('app:serve')
     .description('Serve an app for local development')
-    .action(actionHandler(appServe));
+    .action(actionHandler(() => require('commands/app/serve')));
 
   program
     .command('create-plugin')
     .description('Creates a new plugin in the current repository')
-    .action(actionHandler(createPluginCommand));
+    .action(
+      actionHandler(() => require('commands/create-plugin/createPlugin')),
+    );
 
   program
     .command('plugin:build')
     .option('--watch', 'Enable watch mode')
     .description('Build a plugin')
-    .action(actionHandler(pluginBuild));
+    .action(actionHandler(() => require('commands/plugin/build')));
 
   program
     .command('plugin:serve')
     .description('Serves the dev/ folder of a plugin')
-    .action(actionHandler(pluginServe));
+    .action(actionHandler(() => require('commands/plugin/serve')));
 
   program
     .command('lint')
     .option('--fix', 'Attempt to automatically fix violations')
     .description('Lint a package')
-    .action(actionHandler(lintCommand));
+    .action(actionHandler(() => require('commands/lint')));
 
   program
     .command('test')
     .option('--watch', 'Enable watch mode')
     .option('--coverage', 'Report test coverage')
     .description('Run all tests for package')
-    .action(actionHandler(testCommand));
+    .action(actionHandler(() => require('commands/testCommand')));
 
   program
     .command('watch-deps')
     .description('Watch all dependencies while running another command')
-    .action(actionHandler(watch));
+    .action(actionHandler(() => require('commands/watch-deps')));
 
   program
     .command('build-cache')
@@ -98,7 +90,7 @@ const main = (argv: string[]) => {
       'Cache dir',
       '<repoRoot>/node_modules/.cache/backstage-builds',
     )
-    .action(actionHandler(buildCache));
+    .action(actionHandler(() => require('commands/build-cache')));
 
   program.on('command:*', () => {
     console.log();
@@ -119,10 +111,11 @@ const main = (argv: string[]) => {
 
 // Wraps an action function so that it always exits and handles errors
 function actionHandler<T extends readonly any[]>(
-  actionFunc: (...args: T) => Promise<any>,
+  actionRequireFunc: () => { default(...args: T): Promise<any> },
 ): (...args: T) => Promise<never> {
   return async (...args: T) => {
     try {
+      const actionFunc = actionRequireFunc().default;
       await actionFunc(...args);
       process.exit(0);
     } catch (error) {