Abstract detection logic in seperate file

Co-authored-by: Vincenzo Scamporlino <vinzscam@users.noreply.github.com>
Signed-off-by: Philipp Hugenroth <philipph@spotify.com>

packages/cli/src/lib/bundler/bundle.ts

@@ -27,6 +27,7 @@ import { createConfig, resolveBaseUrl } from './config';
 import { BuildOptions } from './types';
 import { resolveBundlingPaths } from './paths';
 import chalk from 'chalk';
+import { writeDetectedPluginsModule } from './discover';
 
 // TODO(Rugvip): Limits from CRA, we might want to tweak these though.
 const WARN_AFTER_BUNDLE_GZIP_SIZE = 512 * 1024;
@@ -49,6 +50,12 @@ export async function buildBundle(options: BuildOptions) {
     getFrontendAppConfigs: () => options.frontendAppConfigs,
   });
 
+  await writeDetectedPluginsModule({
+    config: options.fullConfig,
+    entry: options.entry,
+    targetDir: options.targetDir,
+  });
+
   const isCi = yn(process.env.CI, { default: false });
 
   const previousFileSizes = await measureFileSizesBeforeBuild(paths.targetDist);

packages/cli/src/lib/bundler/config.ts

@@ -26,23 +26,18 @@ import { isChildPath } from '@backstage/cli-common';
 import { getPackages } from '@manypkg/get-packages';
 import { optimization } from './optimization';
 import { Config } from '@backstage/config';
-import {
-  BundlingPaths,
-  BundlingPathsOptions,
-  resolveBundlingPaths,
-} from './paths';
+import { BundlingPaths } from './paths';
 import { transforms } from './transforms';
 import { LinkedPackageResolvePlugin } from './LinkedPackageResolvePlugin';
 import { BundlingOptions, BackendBundlingOptions } from './types';
 import { version } from '../../lib/version';
 import { paths as cliPaths } from '../../lib/paths';
-import { BackstagePackage, BackstagePackageJson } from '@backstage/cli-node';
+import { BackstagePackage } from '@backstage/cli-node';
 import { runPlain } from '../run';
 import ESLintPlugin from 'eslint-webpack-plugin';
 import pickBy from 'lodash/pickBy';
 import yn from 'yn';
 import { readEntryPoints } from '../entryPoints';
-import path from 'path';
 
 const BUILD_CACHE_ENV_VAR = 'BACKSTAGE_CLI_EXPERIMENTAL_BUILD_CACHE';
 
@@ -132,24 +127,6 @@ export async function createConfig(
     }),
   );
 
-  const detectedPlugins = await detectPlugins({
-    config: options.fullConfig,
-    entry: options.entry,
-    targetDir: options.targetDir,
-  });
-  const requirePackageScript = detectedPlugins
-    ?.map(pkg => `{name: '${pkg}', module: require('${pkg}')}`)
-    .join(',');
-
-  await fs.writeFile(
-    path.join(
-      cliPaths.targetRoot,
-      'node_modules',
-      'backstage-autodetected-plugins.js',
-    ),
-    `module.exports = { modules: [${requirePackageScript}] };`,
-  );
-
   const buildInfo = await readBuildInfo();
   plugins.push(
     new webpack.DefinePlugin({
@@ -388,39 +365,3 @@ function nodeExternalsWithResolve(
     return externals(context, request, callback);
   };
 }
-
-export async function detectPlugins({
-  config,
-  entry,
-  targetDir,
-}: { config: Config } & BundlingPathsOptions) {
-  const paths = resolveBundlingPaths({ entry, targetDir });
-  const pkg: BackstagePackageJson = await fs.readJson(paths.targetPackageJson);
-  // TODO: proper
-  // Assumption for config string based on https://github.com/backstage/backstage/issues/18372 ^
-
-  const packageDetectionMode =
-    config.getOptional('app.experimental.packages') || 'all';
-
-  const allowedPackages =
-    packageDetectionMode === 'all'
-      ? Object.keys(pkg.dependencies ?? {})
-      : config.getStringArray('app.experimental.packages');
-
-  return allowedPackages
-    .map(depName => {
-      const depPackageJson: BackstagePackageJson = require(require.resolve(
-        `${depName}/package.json`,
-        { paths: [paths.targetPath] },
-      ));
-      if (
-        ['frontend-plugin', 'frontend-plugin-module'].includes(
-          depPackageJson.backstage?.role || '',
-        )
-      ) {
-        return depName;
-      }
-      return undefined;
-    })
-    .filter((d): d is string => !!d);
-}

packages/cli/src/lib/bundler/discover.ts

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2020 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { BackstagePackageJson } from '@backstage/cli-node';
+import { Config } from '@backstage/config';
+import fs from 'fs-extra';
+import path from 'path';
+
+import { BundlingPathsOptions, resolveBundlingPaths } from './paths';
+import { paths as cliPaths } from '../../lib/paths';
+
+type Options = { config: Config } & BundlingPathsOptions;
+
+async function detectPlugins({ config, entry, targetDir }: Options) {
+  const paths = resolveBundlingPaths({ entry, targetDir });
+  const pkg: BackstagePackageJson = await fs.readJson(paths.targetPackageJson);
+  // TODO: proper
+  // Assumption for config string based on https://github.com/backstage/backstage/issues/18372 ^
+
+  const packageDetectionMode =
+    config.getOptional('app.experimental.packages') || 'all';
+
+  const allowedPackages =
+    packageDetectionMode === 'all'
+      ? Object.keys(pkg.dependencies ?? {})
+      : config.getStringArray('app.experimental.packages');
+
+  return allowedPackages
+    .map(depName => {
+      const depPackageJson: BackstagePackageJson = require(require.resolve(
+        `${depName}/package.json`,
+        { paths: [paths.targetPath] },
+      ));
+      if (
+        ['frontend-plugin', 'frontend-plugin-module'].includes(
+          depPackageJson.backstage?.role || '',
+        )
+      ) {
+        return depName;
+      }
+      return undefined;
+    })
+    .filter((d): d is string => !!d);
+}
+
+export async function writeDetectedPluginsModule(options: Options) {
+  const requirePackageScript = (await detectPlugins(options))
+    ?.map(pkg => `{name: '${pkg}', module: require('${pkg}')}`)
+    .join(',');
+
+  await fs.writeFile(
+    path.join(
+      cliPaths.targetRoot,
+      'node_modules',
+      'backstage-autodetected-plugins.js',
+    ),
+    `module.exports = { modules: [${requirePackageScript}] };`,
+  );
+}

packages/cli/src/lib/bundler/server.ts

@@ -34,6 +34,7 @@ import {
   includedFilter,
 } from '../../commands/versions/lint';
 import { BackstagePackageJson } from '@backstage/cli-node';
+import { writeDetectedPluginsModule } from './discover';
 
 export async function serveBundle(options: ServeOptions) {
   const paths = resolveBundlingPaths(options);
@@ -171,6 +172,12 @@ export async function serveBundle(options: ServeOptions) {
     },
   });
 
+  await writeDetectedPluginsModule({
+    config: options.fullConfig,
+    entry: options.entry,
+    targetDir: options.targetDir,
+  });
+
   const compiler = webpack(config);
 
   server = new WebpackDevServer(